The role of emotions and moods in traffic

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The role of emotions and moods in traffic
Jolieke Mesken
D-2003-8

The role of emotions and moods in traffic
Interim report of the first phase of a research project
D-2003-8
Jolieke Mesken
Leidschendam, 2003
SWOV Institute for Road Safety Research, The Netherlands

Report documentation
Number: D-2003-8
Title: The role of emotions and moods in traffic
Subtitle: Interim report of the first phase of a research project
Author(s): Jolieke Mesken
Research theme: Road users: the relationship between behaviour, surroundings
and accidents
Theme leader: Drs. I.N.L.G. van Schagen
Project number SWOV: 31.232
Keywords: Psychology, theory, method, behaviour, perception, traffic, driving
(veh), safety.
Contents of the project: Sometimes behaviour in traffic is of an impulsive nature: then we
enter the field of emotions. So far, little is known about the effects
of emotions on performance. This interim report presents the
results of the project ‘Emotions in Traffic’ in its first year. Three
main activities were carried out. First, a theoretical background
was written and suggestions for research were made. Second, a
literature review was carried out on the methods to measure
emotions in traffic. Third, a theoretical introduction and research
plan for the first study was written.
Number of pages: 44
Price: 11,25
Published by: SWOV, Leidschendam, 2003
SWOV Institute for Road Safety Research
P.O. Box 1090
2260 BB Leidschendam
The Netherlands
Telephone +31-703173333
Telefax +31-703201261

SWOV Publication D-2003-8 3
Summary
This report describes the first phase of the project ‘Emotions in Traffic’
which started in January 2001 as a collaboration project between the
University of Groningen and SWOV Institute for Road Safety Research.
Theoretical issues
The concept of emotion is closely related to other concepts: mood and
affect. Affect is generally used as an umbrella term for all kinds of affective
states. Moods are thought to be more non-specific than emotions, and are
thought to last longer than emotions. Emotions are thought to be
intentional, meaning that they are directed towards an object, whereas
moods are not.
Emotions occur when a valued goal or concern is at stake. An event is
cognitively evaluated or appraised by an individual, and it depends on this
cognitive appraisal if, and if so, which emotion will occur.
Effects of affective states
Emotions may lead to thoughts and behaviour that affect performance on a
range of tasks. Effects of emotions are shown in risk perception and risk
taking behaviour, information processing, and memory.
Stress, emotions and performance
These effects of emotions on performance may be relevant for traffic
participation, although research on this topic is limited. Some studies made
a link between stress (an area closely related to the emotions) and task
performance in traffic. However, the knowledge of the relations between
stress and driving can be expanded if insights from the area of emotions
are included.
Emotions and driving
The knowledge of the effects of emotions on thoughts and behaviour and
the knowledge on the stress-performance relationship can be integrated to
gain more knowledge of the relationship between emotions and task
performance in traffic. Only a few studies focussed on emotion and traffic,
and in most cases they were concerned with anger, and not with other
emotions. These studies are reviewed.
Methodological issues
Research on emotions is complicated, not only because the concept is not
clearly defined, but also because there are some methodological
difficulties.
One problem is experimentally inducing emotions. Several methods can be
distinguished (e.g. showing film fragments or asking subjects to recollect an
experience that caused emotions in the past) but their efficiency varies and
it is difficult to tell how long the induced emotion lasts. Another
methodological issue is the measuring of emotions. Three different
methods can be distinguished: observing overt behaviour, physiological
measures and self-reports. Each has advantages and disadvantages, so it
is recommended that a combination of methods is used.

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Research plans
Four general research questions are formulated:
1. Which are the determinants of emotions in traffic?
2. To what extent do emotions affect cognition?
3. To what extent do emotions affect the selection of action?
4. To what extent do emotions affect driving performance?
Four experiments are designed to answer these questions. The first
experiment is a questionnaire study in which possible determinants of
emotions are studied. In the second and third experiment, emotional states
are experimentally induced and the effects on cognitive processing and
behaviour is studied in the laboratory. In the fourth one, experimental states
are induced and the effects on actual driving performance are studied. In
the last study (which is not a real experiment) written reports on aggressive
incidents are qualitatively analysed.

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Contents
1. Introduction 7
2. Emotions and moods: some theoretical issues 8
2.1. Concepts and definitions 8
2.2. The emotion process: appraisal theory 9
3. Effects of affective states 11
3.1. Mood and risk 11
3.2. Mood and information processing 13
3.3. Mood and memory 14
4. Stress, emotions and performance 16
4.1. Definitions of stress 16
4.2. Stress and the emotions 16
4.3. Performance 17
5. Emotions and driving 19
5.1. Driving stress and emotions in traffic 19
5.2. Results from earlier studies 20
5.3. When are emotions (mal)adaptive in traffic? 22
6. Methodological issues 24
6.1. Inducing emotions 24
6.2. Measuring emotions 29
6.2.1. Overt behaviour 29
6.2.2. Physiological measurements 30
6.2.3. Self-report 32
7. Research plans 34
7.1. What are the determinants of emotions in traffic? 35
7.2. To what extent do emotions bias cognition? 36
7.3. To what extent do emotions affect choice of action? 37
7.4. To what extent do emotions affect actual driving performance? 37
7.5. “Experiment 5" 38
7.6. Conclusions 38
References 39

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1. Introduction
This report describes the work that was done during the first year of the
project ‘Emotions in traffic’. The project started in January 2001 as a
collaboration project between the University of Groningen and SWOV
Institute for Road Safety Research. The project has its origins in two areas:
traffic research and emotions research. In the context of traffic, the
research that has been done on emotions has focussed mainly on anger
and aggression. To a lesser extent, there have been studies on stress while
driving and on mood states affecting driving performance. However, no
systematic research has been carried out concerning the role of emotions,
other than anger and aggression, in traffic.
Fundamental psychological research on emotions mainly focusses on
origins, processes, and functions of emotions. Especially in recent studies
extensive knowledge was gathered to construct a clear picture of what
emotions are and how and why they occur. An area that until now did not
receive much attention is the effects of emotions on performance, even
though effects of other 'state factors' were considered (e.g. fatigue, stress
etc.). Many studies dealt with the effect of moods on cognitive processing,
but they focussed on positive versus negative mood, and not on specific
moods and emotions. Also, these studies mainly used laboratory tasks
concerning judgement, creativity or cognitive flexibility. An area that
remains mainly uncovered, then, is how specific emotions (e.g. anger,
sadness, happiness, pride, fear) influence complex and real life task
performance.
The present project aims to shed light on this issue by constructing a series
of experiments. The first experiment is a questionnaire study which
focusses on the determinants of emotions in traffic. The following three
experiments are concerned with the effects of emotions on traffic
behaviour. The total running time of the project is four years, during which
the results of the experiments will be integrated, and this will result in a
dissertation.
During the first year of the project, three main activities were carried out.
First, a theoretical background was written and suggestions for research
were made. Second, a literature review was carried out on the methods to
measure emotions in traffic. This paper was presented on a traffic safety
seminar in Ankara, Turkey. Third, a theoretical introduction and research
plan for the first study was written. This interim report includes the products
of these activities. Also, a research plan for the remaining three years is
added. The structure of the report is as follows: Chapter 2 discusses some
theoretical issues on the topic of emotions. Chapter 3 gives an overview of
studies that have been carried out on the effects of emotions, and moods.
In Chapter 4 the theoretical relationships between stress, emotions and
performance are discussed. In Chapter 5 an overview of studies on
emotions in traffic is presented. Chapter 6 deals with some methodological
issues related to emotion research. In Chapter 7, finally, directions for
future research are discussed.

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2. Emotions and moods: some theoretical issues
2.1. Concepts and definitions
The concept of emotion relates to the occurrence of an event which is
relevant to an important concern or goal. This concern or goal is not
necessarily personally important for the person experiencing the emotion:
sometimes the event violates social norms or values the person may have.
Another characteristic sometimes mentioned is that an emotion will occur
when goal-directed behaviour is interrupted. Two other elements of
emotions are derived from Frijda (1986): action readiness and control
precedence. Action readiness means that the event demands some kind of
action: either to make the event stop (in case it causes ‘negative’ emotions)
or to make it continue (in case of ‘positive’ emotions). Control precedence
means that the event causing the emotion takes away all attention from
other events or tasks: all senses are directed towards the one object or
event causing the emotion.
Oatley and Jenkins (1996) summarize these elements in what they call: “a
working definition of the concept of emotion”:
- An emotion is caused by a person consciously or unconsciously
evaluating an object or event as relevant for a personal important
concern.
- The core of an emotion is readiness to act and the prompting of plans.
- An emotion is usually experienced as a distinctive type of mental state,
sometimes accompanied or followed by bodily changes, expressions,
and actions.
A number of other terms is related to the concept of emotion, like mood,
feeling and affect. The concept of ‘affect’ is often used as an umbrella term
for feelings, emotions, and moods. Feelings, emotions, and moods then
serve as sub-categories. Affect or affective responses are usually
understood as being uni-dimensional: an either positive or negative affect is
present. Feelings, according to Frijda (1986), form the core characteristic
that differentiates affective from non-affective experiences. Feelings are
usually seen as elements of experience that are irreducible to body
sensations or cognition. Although emotions and moods are closely related
concepts, most researchers insist on making a distinction between them
(Ekman, 1994). The duration of the experience is often mentioned as a
distinguishing criterion: emotional experiences are short (between a few
minutes and a few hours) whereas moods can last for days, weeks, or even
months. Some researchers claim that moods lower the thresholds for
certain emotions to occur and also the other way around: the occurrence of
a specific emotion may lead to a mood that will last for a longer time.
Furthermore, emotions are intentional: they always have an object,
whereas moods are non-specific.

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2.2. The emotion process: appraisal theory
The most influential emotion theory among psychologists is appraisal
theory. The first researchers to use the concept of appraisal were Arnold
(1945) and Lazarus (1966). Although Lazarus’ ideas were originally
developed within the area of stress, in 1993 he made an argument to
integrate the two areas, or rather, to see stress as a part of the emotional
domain. In Chapter 4 we will say more about the relations between stress
and emotions.
The general idea behind appraisal theory is that emotions are elicited by
evaluations (appraisals) of events and situations (Roseman and Smith,
2001). It depends on the interaction between an event and an individual
whether an emotion takes place. Appraisal theory does not see an emotion
as a distinct phenomenon, but rather as a process. Within this process
several steps or phases can be distinguished.
The process starts with an event. This is not necessarily something
happening in the outside world: a person can also suddenly remember
something or realise something, which is then called ‘event’ as well. The
first question that is asked by the person perceiving the event, is: How
important is this for me? Something that bears absolutely no relevance for
the person, is not likely to elicit an emotion. The next step is the evaluation
of the event in terms of congruence or incongruence with one’s own
concerns. Events that are congruent with the person’s concerns will elicit
positive emotions; events that are incongruent with one’s concerns will elicit
negative emotions.
Next, there are a number of hypothetical questions a person might ask
himself. Generally speaking, these questions are similar in the appraisal
theories proposed by Lazarus (1991), Frijda (1986), and Scherer et al.
(2001). The answers to these questions may determine the type of positive
or negative emotion that is experienced. For example:
- Who is responsible for this event?
- How well can I cope with this?
- What is the significance of this event for my self-concept and social
norms and values?
- What are the outcome probabilities?
Each emotion is different because the answers to the questions mentioned
above are different. Appraisal is the process of ‘going through’ these
questions. For example, anger is likely to be induced if:
- the event is relevant for one’s concerns;
- the event is incongruent with one’s goals;
- someone else is to blame;
- the event relates to one’s self concept or norms and values.
By appraisal, people scan the environment for events relevant for their well-
being, so the correct response to the event can be selected (for example,
fight, in the case of anger). Therefore appraisal also has an adaptational
value. Sometimes, however, the emotions elicited by appraisal processes

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are maladaptive, such as in anxiety disorders, or the behaviour caused by
emotions is maladaptive, such as in aggression. In Chapter 5 we will get
back to the question when emotions are adaptive and when they are
maladaptive.

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3. Effects of affective states
Emotions can cause behaviour, thoughts, or experiences which have a
direct relationship with the emotion. Sometimes however, behaviours occur
which are not specifically related to the emotion but do occur as an effect of
it. This distinction may be especially relevant for traffic situation: when
people get angry they may start swearing or making gestures (behaviours
related to the emotion), but they also may suffer from attention loss or
decrease in reaction times as a result of anger. Perhaps the kinds of
behaviour that are not so clearly related to the emotion at hand are even
more important in traffic situations, since the effects might do their work
unconsciously. For example, one may not notice that reaction times are
longer when being angry.
A large number of studies investigated the effects of various affective states
on human performance. Memory, judgement, risk perception, attitude
change, impression formation, attention, and creativity: these are all topics
that have been studied in relation to affect. However, research has been
limited in two ways. First, in most studies the focus was on mood or on
general positive or negative affect. The effects of specific emotions
received less attention. An area that remained mainly uncovered, then, is
how specific emotions (e.g. anger, sadness, happiness, pride, and fear)
influence complex and real life task performance.
A reason why emotion researchers have not been concerned so much with
the effects of emotion, was recently proposed by Siemer (2001). It may be
that we are dealing with two distinct research traditions, one which is
concerned with cognitive causes and constituents of affect, like research on
emotion and appraisal, and the other dealing with the effects of affective
states on various cognitive processes. When considering the effects of
affective states on driving performance, a third relevant line can be
distinguished, which focusses on the effects of various state factors (like
stress and fatigue, and recently also moods) on task performance. Another
reason may be that while emotions are believed to have a clear object,
research on the effects of emotional states is more directed towards the
question of how emotional states alter cognition unrelated to the original
object of the emotion (Parrot and Spackman, 2000).
In the previous chapter, insights on emotion processes and theories were
discussed. In the present chapter we will review studies that concern the
effects of affective states on performance. Most of the studies focus on
cognitive processes but some discuss task performance as well.
3.1. Mood and risk
Johnson and Tversky (1983) investigated the relationship between mood
and risk perception in a series of four experiments. In the first and the
second experiment, subjects in the experimental condition had to read
newspaper articles concerning a death of a young undergraduate. It turned
out that subjects in the experimental condition were in a more negative
mood than subjects in the control condition. Furthermore, subjects in the
experimental condition made more pessimistic judgements about the risk of

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getting killed than subjects in the control condition: they gave higher risk
estimates. This effect was a global effect, meaning that it extended to all
causes of death and not only the ones that were similar to the cause of
death mentioned in the newspaper article. In the third experiment, subjects
in the experimental condition were asked to read depressing stories
unrelated to risk of death. Results showed that these subjects also gave
higher ratings of risk of death, supporting the hypothesis that it is the bad
mood, rather than the information in the stories, that cause the more
pessimistic judgements. In the final experiment, subjects read positive
stories and again made judgements on the risk of death by several causes.
Subjects in the experimental condition showed lower levels of perceived
risk of getting killed by various causes than subjects in the control
condition.
Wright and Bower (1992) also showed that people in a positive mood are
optimistic: they report higher probabilities for positive events and lower
probabilities for negative events. People in a negative mood (sad, in this
case) are pessimistic: compared to controls they report lower probabilities
for positive events and higher probabilities for negative events.
These results suggest that a negative mood leads to a higher risk
perception whereas a positive mood leads to a lower risk perception. In
other words, people in a positive mood are optimistic and may therefore
take risky decisions. This was shown by Armitage, Conner and Norman
(1999), who found that a positive mood promotes risky decision making and
more heuristic decision strategies, whereas negative moods instigate a
more problem-focussed approach. The explanation provided is that people
in a positive mood try to maintain that state, and too thorough processing
can interfere with that goal. People in a negative mood, on the other hand,
see many more problems and try to 'repair' their negative mood by
elaborating, in other words, by thinking things through carefully.
Research by Isen (see Isen, 2000 for a review) also shows that positive
moods lead to more risky decisions, but only if the situation which subjects
are presented with is hypothetical. When confronted with a situation where
subjects indeed could win or loose something, subjects in a positive mood
made less risky decisions than those in a negative mood. Leith and
Baumeister (1996) found that a bad mood was associated with more
self-defeating (risk-taking) behaviour, but only in a high arousal - bad mood
condition like anger. Sad subjects did not show any higher levels of
self-defeating behaviour. Angry subjects did also show lower risk-
perception in a study by Lerner and Keltner (2000), as opposed to fearful
subjects.
These results seem to point in the direction that sad and fearful subjects
are likely to perceive risks as higher and have lower inclinations to take
risks than angry subjects. The opinions about subjects in positive mood are
less clear: are they risk-averse because they want to maintain the positive
mood, or are they more likely to take risks because of an illusion of control?
It needs to be said that all reported studies were carried out in the
laboratory, using lottery games, pencil-and-paper risk estimations, and so
on. We do not know of studies linking positive and negative mood, or even

SWOV Publication D-2003-8 13
specific emotions to risk perception and risk taking behaviour, in real life
situations like traffic.
3.2. Mood and information processing
People in a good mood tend to process information in a less systematic
way and rely more on heuristic cues than people in a bad mood. This was
shown first in relation to attitude change (Mackie and Worth, 1991; see
Eagly and Chaiken, 1993, for a review on mood and persuasion) and later
also in relation to social judgement (Bodenhausen et al., 1994). Sinclair and
Mark (1995) showed that happy subjects were less accurate in estimating
correlation coefficients from scatter plots than sad subjects. Several
explanations have been offered for this phenomenon, the most important
being that mood has a signal function: a bad mood means something is
wrong and something has to be done about it, and a good mood means all
is well (Armitage et al., 1999). Sinclair, Mark and Clore (1994) extended this
hypothesis by arguing that the more elaborate processing of sad subjects is
caused by misattribution. When people are in a bad mood, they tend to
perceive their mood as a reaction to the situation which then means that
something is wrong and something needs to be done. Therefore
elaboration will be high. This is called the ‘mood as information hypothesis’.
However, Sinclair et al. (1994) showed that people who attribute their mood
to an external cause (e.g. the weather) do not show greater elaboration
when being in a bad mood.
The different processing styles of happy and sad subjects lead to different
levels of performance on different tasks. Performance on tasks that require
detailed processing are facilitated by a negative mood. Performance on
tasks that require creative and 'playful' processing is facilitated by a positive
mood. However, Hirt et al. (1997) claimed that if the effects of moods are
caused by misattribution (mood as information), then the mood effects
should be eliminated if subjects are made aware of their mood and the fact
that the mood has been caused by something else. They did an experiment
in which they cued half of the subjects on the true source of their mood.
The other half of the subjects were not cued. It appeared that cuing the
subjects on the source of their mood had an effect on quantitative
measures of performance. However, cuing did not affect creativity. The
authors conclude that the mood-as-information view does not apply to
creativity. It is not exactly clear yet through which processes positive mood
does affect creativity, but explanations must be sought (according to the
authors) in theories of mood management or affective priming. Mood
management refers to the phenomenon that people want to maintain their
positive mood and are unwilling to engage in activities that include careful
systematic processing. Affective priming means that affect is linked to
similar concepts in the brain.
Dibartolo et al. (1997) showed that subjects with a generalised anxiety
disorder showed poorer task performance of a laboratory task than normal
comparison subjects. However, this difference was noted only during
baseline trials and not during experimental trials. One explanation that is
provided is that anxious subjects become aware of the interfering role of
their anxiety with the task, and allocate an extra amount of effort to the task
at hand during the experimental trials. Therefore, the final performance is

14 SWOV Publication D-2003-8
equal to the performance of normal comparison subjects. It should,
however, be noted that mood effects might be different for people with
mood disorders than for non-clinical subjects. People who are afraid of
driving might show different behavioural responses in traffic than those who
are suffering from anxiety disorder which is not related to traffic.
3.3. Mood and memory
Parrot and Spackman (2000) give an extensive review of studies
investigating the effect of emotional states on memory. First of all they note
that in these studies, no consistent distinction has been made between
mood and emotion. This is a general problem of studies on the effects of
emotional states on performance, as we have seen before. In their review
chapter, Parrot and Spackman use the terms 'emotion' and 'mood'
interchangeably, as we will do in this paragraph as well.
Emotions can influence memory in three ways. One applies to the
emotional valence (positive or negative value) of the material to be
remembered. The second applies to the emotional state of the person at
the time the material is encoded in memory. And the third applies to the
emotional state of the person at the time of retrieval of the material. Most
studies considered the interaction effects of emotional states during
retrieval and emotional content of the material. Early studies mostly showed
mood-congruent recall, that is, persons in a happy mood recalled positive
information, whereas persons in a sad mood recalled negative information.
This phenomenon was first explained by the associative network theory.
According to this theory, human memory can be modelled as a network of
concepts, linked together to describe an event. Emotions are thought to be
represented in the network and are related to emotional events and
concepts. The activation of an emotion leads to activation of related
emotional concepts and events, and therefore facilitates memories that are
similar in emotional valence.
The need for other explanations for mood-memory relationships became
obvious when other studies started to show incongruent recall as well:
remembering negative events when being in a positive mood and vice
versa. This led to the development of motivational theories, which claim
that persons' moods are important for the memories they recall. Memories
can be retrieved to maintain or change a person’s plans, goals, or moods.
A study by Levine and Burgess (1997) showed the distinct effects of
specific emotions on memory. Subjects were brought in a happy, angry or
sad emotional state and were then presented with a positive or negative
narrative. Each narrative contained information on setting, goal, agent,
outcome, and consequence. Results showed that happy subjects showed
better memory of the narrative as a whole. Angry and sad subjects showed
better recall of only parts of the information in the narrative: angry subjects
recalled more information related to goals, whereas sad subjects recalled
more information related to outcomes.
The research that has been reviewed in this chapter concerns mainly
laboratory studies, which deal with cognitive processes rather than with real
life task performance. Also, most studies in this area focus on general

SWOV Publication D-2003-8 15
positive or negative affects or moods. What is lacking is theoretical
knowledge about how specific emotions affect complex and real life task
performance, and to be more specific, in which cases emotions are
beneficial to driving performance and in which cases they are destructive.
Therefore, in the next chapter we will turn to a topic which is closely related
to emotions but where a much broader theoretical background exists on the
effects on performance: the area of stress.

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4. Stress, emotions and performance
4.1. Definitions of stress
The concept of stress is complex and vague. Not only are there a number
of different definitions, but also the processes that have been studied under
the umbrella term of stress are of a very different nature (Buunk and
Gerrichhauzen, 1993). However, the definitions that have been proposed
over the years can be broadly summarised in three viewpoints. In the
earliest views, stress was seen as a characteristic of the environment: a
load that was put on the subject. Later on, the emphasis was put on the
subject who reacted to an external threat. Nowadays, stress is usually
defined from an interactionist point of view. It is not just the environment
that is causing stress, because equal situations cause stress reactions in
one person but not in the other. Neither is it a personality characteristic,
because the same person might respond differently to different stressful
stimuli. Instead, stress is a result from a dynamic interaction between
person and environment. Specifically, in interactionist definitions stress
results from environmental demands and personal capabilities that are not
in congruence with one another.
Lazarus and Folkman (1984) proposed a definition of stress that is still
widely used nowadays. According to them, stress occurs when:
a) someone judges a stimulus or event as harmful, and b) doesn’t see
(enough) possibilities to handle the stimulus or event. As a result of stress,
stress reactions may occur, such as physical illnesses, disruption of
behaviour, and negative emotions. According to Lazarus en Folkman’s
viewpoint of stress, appraisal is a central theme. Appraisal means the
continuous evaluation of the external environment by the person. Thus,
during the occurrence of stress, two different kinds of appraisal take place:
the evaluation of a stimulus as harmful (primary appraisal) and the
evaluation of personal capabilities as being insufficient (secondary
appraisal). The stimulus or event that is evaluated is not called the stressor,
because it depends on how it is appraised by the individual whether it
causes stress or not.
4.2. Stress and the emotions
The area of stress is closely linked to the area of emotions. However, the
literature on stress and the literature on emotions have mainly been treated
separately. Therefore, Lazarus (1991, 1993) proposed an integration of the
two theories. In fact, he claims that current interactional theories of
psychological stress come very close to a theory of emotion. An
interactional theory of stress defines the appraisal process that leads to
negative emotions. The negative emotions result from a person-
environment relationship that is harmful or threatening for the individual.
However, there can also be beneficial person-environment relationships,
contributing to the well-being of the individual, which lead to positive
emotions. Thus, in the understanding of how individuals adapt to the
environment, Lazarus concludes that the stress theory is too restrictive and
actually covers only half of the topic. Instead, he proposes a theory which

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he calls a cognitive-motivational-relational theory of emotion. According to
this theory, each emotion has a ‘core relational theme’, this is what the
emotion is all about. Which emotion occurs as a result of a specific person-
environment encounter, depends on a range of appraisal components,
divided in two categories: primary appraisal and secondary appraisal. Note
that these terms are used a bit differently in emotion theory than in stress
theory (see Paragraph 4.1.). The primary appraisal components are goal
relevance, goal congruency, and type of ego involvement, whereas the
secondary appraisal components are blame or credit, coping potential, and
future expectations. The combination of the specific appraisal components
define which emotion occurs. Stress, in the viewpoint of Lazarus, is
therefore seen as a particularly harmful, threatening or challenging person-
environment relationship, and it depends on the specific appraisal
components which (negative) emotion occurs.
An example may shed some more light on this theory. Consider a situation
on a highway, where a car driver is driving in the right lane. From a merging
lane on the right, another car is approaching. The car driver moves to the
left lane, just in front of the first car driver, who has to hit the breaks heavily
to avoid a collision. The first driver may appraise the event as follows.
There is goal relevance, since the goal of the driver is to avoid a collision.
There is goal-incongruence, since the event may actually cause a collision,
so the goal is threatened. The ego-identity is affected if the event is seen as
an assault. These are the primary appraisal components. Secondary
appraisal components are blame (the other driver is responsible), coping
potential (it is possible to attack, for example by close following, as a
reaction to the offence) and future expectations (the expected
consequences of the attack are positive, e.g. the other car is not a police
car).
4.3. Performance
The relationship between stress and performance has been studied
thoroughly. Perhaps the earliest insight in this area came from Yerkes and
Dodson (1908). They showed that the relationship between arousal and
performance can be seen as an inverted U-curve: under moderate levels of
arousal the level of performance increases but when the level of arousal
gets too low or high, performance decreases. The optimum level of arousal
is reached earlier when the task is complex than when the task is easy.
Although the Yerkes-Dodson law has been criticised heavily, it still remains
one of the most cited insights in performance literature. It must be noted
however, that the concept of stress is not used in the original publication,
but the concept of arousal has been interpreted as stress level by other
scientists in later years.
One of the criticisms of the Yerkes-Dodson law was that it focuses on
arousal, whereas there are other ways in which stress may affect
performance, for example by distraction or by changing perception
(Matthews et al., 2000). Therefore, cognitive scientists have tried to identify
the mechanisms through which stressors have an effect on performance.
Many of these effects have been established. Hockey (1986) summarises
the effects of various stressors such as noise, heat, fatigue, and anxiety on
performance indicators, such as selectivity of attention, speed, and

18 SWOV Publication D-2003-8
accuracy. His analysis shows that different stressors can have similar
effects on task performance. Also, the same stressor can have different
effects on different components of task performance. Hockey does see
stressors as independent factors influencing performance, independent of
appraisal, whereas Lazarus thinks appraisal is needed before one can
speak of stress. However, the concepts are not very clear here, as can be
seen from the collection of stressors. From Lazarus’ point of view, for
example, anxiety is not a stressor but something that may occur as a result
of stress.
The integration of stress and emotion, or, if you will, the capturing of stress
theory in emotion theory, offers a lot of possibilities for explaining the
stress-performance relationship. The reactions that people show under the
influence of task environment, can be extended with reactions or action
tendencies (Frijda, 1986) to emotions. In other words, the task environment
may lead not only to negative emotions as a result from stress, but also to
other negative and positive emotions. Lazarus describes about 15 different
emotions, each with their own theme or story, and each emotion can lead to
different action tendencies. So, when applying Lazarus’s emotion theory to
the topic of task performance, two issues are important. First, it is likely that
performance is not only affected by anxiety, anger, and frustration etc. (the
typical stress reactions), but also by joy, pride, sadness, and other
emotions. Second, it is not the stress itself that causes changes in
performance, but the emotions that result from the person-environment
relationship. Unfortunately, the concept of stress and the concepts of
emotional reactions to stress (like anxiety) are often used interchangeably
in performance literature, making it difficult to differentiate between the
concepts.

SWOV Publication D-2003-8 19
5. Emotions and driving
Generally it is believed that emotions are functional, that they promote
adaptation to the demands of the environment. The emotion of fear, for
example, causes action tendencies to avoid or escape, which is beneficial
when being faced with a physical threat. However, sometimes emotions are
maladaptive. This happens when specific action tendencies which occur as
a result of the emotion, are not fit for the demands of the environment at
that very moment. Also, sometimes certain behaviour occurs as a side-
effect of the emotion, (for example narrowed attentional focus when being
angry) which may turn out to be maladaptive. In this chapter we will try to
integrate the viewpoints of the earlier chapters and apply them to the area
of traffic. In particular, we will elaborate on the question when emotions are
adaptive (beneficial) and when they are maladaptive (harmful) for
performance on the driving task.
5.1. Driving stress and emotions in traffic
Keeping in mind the links that exist between stress and emotions, studies
on stress and driving can, for several reasons, be viewed in a new
perspective. First, the studies assume a direct link between stress and
driving. However, as was shown before, the existence of stress leads to
stress reactions such as negative emotions. It can be assumed then, that it
is not the stress itself (the mismatch between task demands and personal
capabilities) that leads to a change in driving performance, but the negative
emotions that result from it. Consequently, emotions can be seen as a
mediating variable between stress and driving performance.
Second, when restricting oneself to stress and driving performance, the
focus is on negative emotions resulting from stress. However, one then
neglects the effects of positive emotions, resulting from other causes, which
may affect driving performance as much as negative emotions. For
example, many studies showed a relationship between positive mood and
risk taking behaviour (e.g. Armitage, Conner and Norman, 1999; Isen,
2000; see also Chapter 3). Also, research by Levelt (2001) showed that an
emotion occurring regularly in traffic is pride about ones own abilities to
drive fast in a safe way.
Thirdly, as a more methodological point, the concepts of stress and
emotion are confused in studies on stress and driving. Quite often, anxiety
or anger is measured, and considered to indicate the level of experienced
stress. However, if one would want to measure stress, one would have to
measure first how the task demands are appraised by the individual, and
second how the individual capabilities to cope with the task demands are
perceived. The anxiety and anger are just the emotional reactions that
result from stress.
Because of these reasons, the focus of new studies should be more on the
emotion-driving performance relationship than on the stress-driving
performance relationship. The stress and driving studies offer interesting
insights, but the picture is not complete.

20 SWOV Publication D-2003-8
5.2. Results from earlier studies
As early as 1967, a study was carried out about the effects of mood on
performance in a driving simulation task (Heimstra et al., 1967). Subjects
filled out the Mood Adjective Check List (MACL) prior to the driving
simulation task. The MACL consists of a list of mood adjectives, such as
anxious, sad, or relaxed etc. After each adjective four symbols are placed,
for example:
Anxious vv v ? no
When the subject was sure to feel anxious, he had to draw a circle around
the ‘vv’ symbol, if he was to feel slightly anxious, he had to mark the ‘v’
symbol, if he wasn’t sure hoe he would feel he had to choose ‘?’ and if he
would not feel anxious all he had to mark ‘no’. Only four mood factors were
considered: aggression, anxiety, concentration, and fatigue. Results from
the study showed that correlations between mood factors and task
performance measures were low. Subjects’ mood did not seem to relate to
a large extent to task performance. However, when high scores and low
scores on the mood factors were compared, subjects scoring high on
aggression, anxiety, and fatigue performed poorer than subjects scoring
low on these factors.
In 1980, a similar study was carried out by Appel and colleagues, but this
study linked mood and performance in a real life driving situation: the
performance of driving school students on a driving task on a slippery road.
In this study as well, a mood adjective checklist was used. The adjectives
form six dimensions, four of which were used in this study: pleasantness,
activity, calmness, and confidence. Results from the study showed that
pleasantness, calmness, and confidence were negatively related to error
scores on one of the subtasks: subjects who felt more pleasant, more calm,
and more confident made less errors.
Until now, research on emotions (as opposed to moods) in traffic mainly
focussed on aggressive driving (see for example Levelt, 1997, Lajunen et
al, 1998; Hennessy & Wiesenthal, 1999; Lajunen & Parker, 2001). Results
from a survey carried out by the British Automobile Association (Joint,
1995) showed 90% of all respondents reported to have been involved in an
aggressive incident in traffic during the previous year. It should be noted,
however, that ‘aggressive incidents’ were defined very broadly in this study,
including people sounding the horn or giving light signals. Although it is
generally assumed that aggression in traffic is preceded by anger, not all
studies reporting aggressive driving relate aggression to anger. Hartley and
Hassani (1994) for example, view aggression as part of a range of state
factors, which together constitute the concept of driver stress. Sometimes a
distinction is made between instrumental and affective aggression:
instrumental aggression is assumed to be related purely to ‘getting ahead’
whereas affective aggression involves an anger component and is directed
to other road users. However, it is also possible that emotions play part in
instrumental aggression, but to what extent is as yet not clear.
Some studies focussed specifically on anger while driving. Deffenbacher et
al. (1994) developed a driving anger scale, which yielded 6 sub-scales:

SWOV Publication D-2003-8 21
anger provoked by hostile gestures, illegal driving, police presence, slow
driving, discourtesy, and traffic obstruction. Lajunen et al. (1998) carried out
factor analysis on responses to the items by a British sample, resulting in a
scale with 21 items and 3 subscales: progress impeded, direct hostility, and
reckless driving. Arnett et al. (1997) conducted a study during which they
asked 59 adolescent drivers to keep a log of their driving episodes over a
10 day period. One finding of the study was that an angry mood (but not
other moods) was related to speeding behaviour.
Only a few studies report on emotions other than aggression in traffic.
Myrtek and colleagues (1994) made a distinction between increased heart
rate due to physical activity on the one hand, and increased heart rate due
to emotional load on the other. They measured muscle activity and heart
rate for train drivers, and compared the values for any given minute with the
values of the previous minutes. If the heart rate of a given minute exceeded
the rate of the previous minutes without an accompanying increase in
physical activity, an emotional/mental heart rate increase was assumed.
Results indicated that when speed was less than 100 km per hour, no
changes in heart rate occurred compared to a standing still position. When
speed was between 100 and 200 km per hour, a decrease in heart rate
occurred, presumably due to monotony effects. Starting the train and
coming to a halt showed greater emotional workload as compared to
moving.
Carbonell et al. (1997) investigated how anxiety and stress in certain traffic
situations can lead to traffic accidents. They suggest that, for professional
drivers, anxiety combined with time pressure can lead to carrying out
dangerous manoeuvres, thus increasing accident risk. Groeger (1997)
studied the relationships between drivers, their moods, and their driving
performance; both as they themselves believe it to be, and as observed by
an experienced observer. Three mood indices were considered: anxiety,
depression, and hostility. In general, those who are more anxious perform
less well than less anxious subjects. Also, when hostility increases during
the test, performance seems to deteriorate.
Jessurun (1997) used electromyography (EMG) to measure drivers’
appraisal of two different road environments. She showed slides of the two
road environments to subjects and measured activity of the corrugator
supercilii (the muscle above the brow, used in frowning). A difference in
EMG activity was shown, the more monotonous road causing more activity
of the corrugator supercilii than the less monotonous road. So, the more
monotonous road caused more negative feelings. This was also reflected in
self-report measurements in which the subjects rated the monotonous road
as less pleasant than the other road.
Levelt (2001) studied emotions and moods in car drivers and lorry drivers.
Moods were described in terms of two factors: calm-energetic and
agitation-irritation. It was shown that drivers who agree that they are often
in a agitated or irritated mood, also agree that often speeding is the
consequence. Furthermore, enjoying driving fast and being proud to drive
fast in a safe way were reported by a quarter of the drivers. They were
related to violations of speed limits and overtaking prohibitions, as well as
the number of fines. Irritation, caused by a slow driver, causes

22 SWOV Publication D-2003-8
hooting/flashing and close following, and is related to violations and the
number of fines.
5.3. When are emotions (mal)adaptive in traffic?
To answer the question in which cases emotions are maladaptive in traffic,
it is necessary, first, to take a stand in the discussion about whether
emotions should be seen as categories or as dimensions. In Lazarus’s view
emotions can be fitted in categories, each with their own relational theme.
Other scientists: Plutchik, (1980), Watson and Tellegen, (1985) have taken
a dimensional approach, in which all emotions fit on a circumplex defined
by two dimensions, e.g. positive and negative affect or valence and
arousal. Especially when studying the effects of emotions on task
performance, it is important which viewpoint is taken, since the predictions
of the two viewpoints would be quite different. Take, for example, anger
and anxiety. In an arousal-valence dimensional approach, these two
emotions would be placed close together on the circumplex and have
similar effects on task performance. But in a categorical approach, the
underlying appraisal themes of anger and anxiety are totally different from
each other, leading to different effects on task performance. Lerner and
Keltner (2000) put the two approaches against each other and tested
whether anxiety and anger have different effects on risk perception. Their
study showed that fearful people made pessimistic judgements about future
events, whereas angry people made optimistic judgements.
This study is also relevant for traffic research, since risk and risk perception
are important factors in driving. Based both on this study and on Lazarus’s
theory of emotion, it seems legitimate to favour the categorical approach
over a dimensional approach when studying the effects of emotions on
driving performance. We assume that each emotion has its own specific
effects on driving performance. The question is then, through which
processes these effects occur, and when the effects are beneficial
(adaptive) or harmful (maladaptive), that is, promoting traffic safety or
endangering it.
Frijda (1986) reviews a number of hypotheses on emotional disturbance
and energizing. One of these is called the response competition hypothesis.
According to Frijda, it depends on the relevance of a particular behaviour
for the task at hand, whether this behaviour improves or deteriorates under
the influence of emotion. Frijda gives an example of a football team, made
angry at the opposing team by the coach just before the start of the match.
The anger may result in running and kicking with force, which is especially
adaptive in this situation. Likewise, anxiety in traffic will be adaptive if the
task is, for example, keeping at a safe distance from the lead car, since the
behaviour resulting from anxiety has to do with avoidance or escape. On
the other hand, if the task at hand is following another car with high speed,
anxiety will be maladaptive because the behaviour resulting from anxiety is
incompatible with the task. Related to this is what Wickens (1992, p. 419)
says about stress and decision making: “The effects of stress on decision
making depends on the components of the decision making which are
relevant: since different decisions may involve varying dependence on such
components as working memory, attention and long-term memory retrieval,

SWOV Publication D-2003-8 23
each decision will be affected differently by stress as a function of the
components on which it depends.”
This also means that positive emotions such as happiness and pride may
have averse effects on task performance. Likewise, negative emotions like
fear can have positive effects. All depends on whether emotional responses
coincide with task-relevant responses.
Other hypotheses on the emotion-performance relationship can, in my
opinion, be summarised by the term ‘cognitive bias’. It refers to those
instances in which emotions cause changes in judgement, attentional
focus, information processing, distraction, etc. These effects are not so
much concerned with the primary function of the emotion, but are, in a way,
unintended consequences.
Consider, for example, a study by Matthews et al. (1998). They considered
anxiety to be a central part of the driver stress dimension ‘dislike of driving’.
Anxiety, they claimed, has two effects on driver performance. First, anxiety
may lead to a diversion of attention, leading to more driving errors. Second,
anxiety may increase the perceived danger of the task, leading to a
decrease in risk taking behaviour. The concept of anxiety can, according to
Lazarus (1991), be described as an uncertain, existential threat. The action
tendency belonging to anxiety would be avoidance or escape. The
response competition hypothesis would predict that performance will
decrease if emotionally motivated behaviour and behaviour required by the
task are conflicting. In this case (assuming that the task in this case would
be safe driving), the action tendency of avoidance does not conflict with the
behaviour required from the task (risk avoidance). Therefore in this case
performance does not decrease. However, from the cognitive bias
hypothesis point of view, anxiety also leads to unintended consequences,
like distracting thoughts or cognitive interference, leading to more driving
errors. Thus, the same emotion, in this case anxiety, can have both positive
and negative effects on performance and these effects can actually occur
at the same time in the same task environment.
To establish, then, the effects of each emotion on driving performance, one
should specify the action tendencies that result from the emotion, specify
the task (components) in which one is interested, and establish the
cognitive biases that may occur as a result of the emotion.

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6. Methodological issues
In this chapter we will address some methodological issues that are
relevant when studying emotions in traffic. We will discuss respectively the
issue of inducing emotions in the laboratory, and the issue of measuring
emotions.
6.1. Inducing emotions
A large variety of methods has been used to induce emotional states in the
laboratory. Generally, no distinction is made between the concepts of
moods and emotions, although there are exceptions (Philippot, 1993). For
example, in a review by Gerrards-Hesse et al. (1994) a footnote is made:
"Here as well as in the following; emotion, emotional state, mood, and
mood states are used as synonyms". When studying the effects of specific
emotions on performance, inducing a positive or negative emotional state is
not enough. One has to be sure that a specific emotional state is present,
because it is believed that each emotion has different adaptational
functions, and that the effect of each emotion on performance is dependent
on these functions.
In the next section an overview is given of studies using emotion induction
procedures and their effectiveness. For each procedure, the type of
intended emotional state is mentioned (general or specific, moods or
emotions). Where possible, something is said about the duration of the
emotional state induced.
Video
Hirt et al. (1997) studied the effects of mood on cognitive laboratory task. A
happy or a sad mood was induced in subjects: subjects in the 'happy'
condition watched videoclips from films like 'Pretty Woman' and 'Mrs.
Doubtfire'. Subjects in the 'sad' condition watched clips from films like
'Ordinary People' and 'Sophie's Choice'. Both before and after the task, the
mood was measured and both showed significant effects of the mood
manipulation. There is no information about how long the effect lasted.
Asuncion and Lam (1995) studied the effects of mood on memory. A happy
mood was induced by having subjects watch comedy video clips. A sad
mood was induced by having subjects watch videoclips showing a Ronald
McDonald house where children with cancer were interviewed. Mood
manipulation checks were carried out right after the manipulation but not
after the task. The mood manipulation was effective: both mood states
differed statistically significant in the expected direction from a control
group. Mood state was not measured after the task, so no knowledge exists
about the duration of the mood state.
Rosselli et al. (1995) studied the processing of rational and emotional
messages. Either a happy or a neutral mood was induced. Subjects in the
'happy condition' viewed a 5 minute video clip from a comedy series.
Subjects in the neutral mood condition watched a 5 minute videoclip about
wine. Mood manipulation checks were carried out after watching the

SWOV Publication D-2003-8 25
video's. Subjects in the happy mood condition rated their moods as more
positive than subjects in the neutral mood condition.
Video / experimental manipulation
Leith and Baumeister (1996) used different techniques to induce positive
and negative moods. In study 2, for positive mood, videoclips were used.
For negative mood, subjects were told that they were supposed to sing
aloud the lyrics of a song: "I did it my way" by Sinatra. This was supposed
to evoke feelings of embarrassment and anxiety. The mood manipulation
check showed that all subjects gave reports that corresponded to the mood
manipulation. However no average scores or significance levels are given.
In study 3, good mood and angry mood were considered. It was believed
that merely watching a videotape would not evoke sufficient levels of anger
in respondents. Therefore, to induce anger, an experimental manipulation
of the situation was used. Respondents were encouraged to recall an
episode in which they had been very angry, but in the middle of this
recollection (which involved actual expression of the anger on an audio
tape, for example shouting and swearing) the procedure was interrupted
several times by the experimenter. Manipulation checks showed that the
mood manipulation was successfull. Study 4 used the same anger
induction procedure as study 3. In study 5, sad mood was evoked by
showing videoclips. All manipulations were successful.
Experimental manipulation
Levine and Burgess (1997) studied the effects on specific emotions
(happiness, anger, and sadness) on memory. Happiness and negative
emotions were induced in undergraduate students by randomly assigning a
low (D) or high (A) grade on a surprise test. It was expected that the
subjects who received a ‘D’ would experience a broader range of emotions
than subjects receiving an ‘A’. Because of this, the group of students
receiving a ‘D’ was bigger than the group receiving a ‘A’. Manipulation
checks (a question after the memory task, asking how the subject felt right
before the memory task) showed that subjects receiving an ‘A’ were more
happy than subjects receiving a ‘D’. Subjects receiving a ‘D’ were more sad
and more angry than subjects receiving a ‘A’. Questions were directed at
the 'primary emotion'. Therefore, in later analyses, distinctions could be
made between subjects who felt mainly angry, and subjects who felt mainly
sad after receiving a ‘D’.
Video / success / failure
Forgas (1995) studied the effects of mood on judgement and memory
about prototypical and atypical targets. In experiments 1 and 2, video
fragments were used to induce either a happy or a sad mood. Experiments
3 and 4 used a false feedback mood induction procedure. The mood
induction procedure was introduced as a test of verbal abilities. A set of 33
questions was presented. On average, people completed 19 questions in 5
minutes. Subjects in the positive mood condition were told that the test was
difficult and few people completed more than 10 questions in 5 minutes.
Performance between 7-13 questions completed within 5 minutes was
described as 'average' and over 13 as ‘above average’, indicating superior

26 SWOV Publication D-2003-8
verbal ability. Subjects in the negative mood condition were told that the
test was easy and that most people completed the test in 5 minutes. For
this group, average performance was described as 27-30 items completed,
with more than 30 items as ‘above average’. Performance below 27 items
was labelled as 'below average'.
Both the manipulations in experiment 1 and 2, and the one in experiment 3,
were effective: subjects in the 'happy' condition rated their mood as more
positive than controls and subjects in the 'sad' condition rated their mood as
more negative than controls. The manipulation check was carried out after
the manipulation, but before the judgement task. Subjects had to rate their
mood on 7-point scales: happy-sad, good-bad and satisfied-dissatisfied. It
seems that possible emotion blends were disregarded here: it could be
expected that subjects who scored below average were not only sad but
angry as well.
Success / failure
Hockey et al. (2000) studied the effects of mood on risk taking behaviour. In
study 1 and 2, mood was measured but not manipulated. In study 3, a
mood manipulation procedure was used: one group of subjects had to work
in a group on a difficult task which could not be completed because of
unexpected problems. The other group spent the time in private study and
unstructured group discussions. The main goal of the manipulation was to
induce fatigue. Manipulation checks showed that subjects in the
experimental group were more tired and anxious, but not more depressed
than the control group. Manipulation checks were carried out after the 'risk
task', but it is not clear how much time it took for subjects to finish the task.
Therefore it is not clear how long the induced mood had lasted.
Imagine / music
Siemer (2001) makes a distinction between moods and emotions. In the
study, the effects of mood on emotion judgement were investigated. Mood
(angry, anxious, or sad) was induced using the autobiographical
recollection method (asking subjects to recall an event which caused anger,
sadness or anxiety) and a mood induction method in which pieces of music
which are known to induce certain moods, were used. Whereas differential
effects were clearly demonstrated for the sadness and anger induction
procedure, the differential effectiveness of the anxiety induction was less
clear, at least when compared to the sadness condition. That is, rather than
a specific anxious mood, the anxiety induction method seems to have
induced a general negative mood state of unhappiness. The mood
manipulation check was carried out immediately after the mood induction
procedure, but not after the judgement task, so it cannot be stated with
certainty whether the effects lasted throughout the task.
Imagine
Sedikides (1992) studied the effects of happy and sad mood on
self-focussed attention. Happy and sad moods were induced using a
guided imagery task. Subjects in happy mood were asked to imagine for 2
minutes that they had won a free cruise in the Caribbean. They were given
brochures with pictures of cruises to help the imagination, and they were

SWOV Publication D-2003-8 27
given 3 minutes to write about the event. Subjects in the sad condition were
asked to imagine for 2 minutes that they had been burnt in a fire and
seriously disfigured. They were given photographs of burnt victims and
were given 3 minutes to write about it. Manipulation checks showed that the
procedure was effective.
Music
Byrne and Eysenck (1995) used two different pieces of music to induce a
neutral or anxious mood. State anxiety was measured before and after the
mood induction. In the anxious mood condition, subjects felt significantly
more anxious after than before the mood induction. However in the neutral
mood condition, there was also a small difference in state anxiety: subjects
reported to be slightly more anxious after the mood induction procedure
than before.
Velten
Bartolic et al. (1999) studied the effects of experimentally induced
emotional states on frontal lobe cognitive performance. Mood was induced
using the Velten mood induction procedure. In this procedure, subjects are
presented with a series of self-referent statements, visually (written on
cards) and orally (played from an audio tape). Subjects are asked to read or
listen to the statement carefully, and try to experience the mood suggested
by the statements. Statements vary from relatively neutral ("Today is no
different from any other day") to elation ("I really do feel good") or
depression ("Every now and then I feel so tired and gloomy that I'd rather
just sit than do anything"). Subjects in the positive emotion condition
reported more euphoric affect than those in the negative condition.
Subjects in the negative condition reported more dysphoric affect than
those in the positive condition.
Armitage et al. (1999) also used the Velten mood manipulation procedure
in two studies on mood effects on information processing. In both studies,
the mood manipulation was effective with subjects in the positive condition
reporting a more positive mood than subjects in the negative condition.
Sinclair and Mark (1995, study 1) induced happy, neutral, and sad moods
using the Velten method. In study 2, using the same method, both affect
and arousal were induced independently. In both studies the manipulation
was effective.
Pictures / story
Forgas (1998) carried out a field study investigating the effect of mood on
helping behaviour. Students who came to study in the university library
found an envelop on the desk containing either positive (humourous
cartoons) or negative (pictures of car accidents) images. They were then
approached by a confederate asking for a favour (giving some sheets of
writing paper). Responses were recorded and immediately afterwards the
subjects were told that this was a social psychology experiment and asked
whether they would answer a few questions. Mood manipulation checks
were part of these questions. Subjects were asked to rate their mood at that

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moment and immediately after viewing the images. In both cases, subjects
in the negative condition rated their mood as worse than those in the
positive condition. A second study used approximately the same procedure,
but instead of images, written texts were used to induce either a happy
(comic episode), sad (narrative about death from cancer), and neutral
(library information) mood. Again subjects were asked to rate their mood
immediately after reading the text and after the experiment. The effects
were similar to the first experiment and lasted throughout the experimental
episode.
Gift
Isen (2000) carried out a series of studies on positive affect and its effect
on cognitive processing. In many of these studies, positive affect was
induced by giving subjects a small bag of candy just before they had to
perform several tasks. In one study (Nygren et al., 1996), the order of the
tasks were varied because affect inductions of this sort usually last not
longer than about half an hour. However, analyses revealed no order
effects, meaning that the mood manipulation was effective throughout the
experiment.
Gerrards-Hesse et al. (1994) made a review of experimental inductions of
emotional states and their effectiveness. Experimental mood induction
procedures (MIPs) can be categorised in five groups:
1. MIPs based on the free mental generation of emotional states;
2. MIPs based on the guided mental generation of emotional states;
3. MIPs based on the presentation of emotion-inducing material;
4. MIPs based on the presentation of need-related emotional situations
(manipulating the situation in a way that it induces emotion);
5. MIPs aiming at the generation of emotionally relevant physiological
states.
Most effective MIPs seem to be:
For positive mood: Film/story MIP, Gift MIP;
For negative mood: Imagination MIP, Film/story MIP, Success/Failure MIP,
Velten MIP.
The authors conclude that if one wants to use the same MIP to induce both
positive and negative moods, the film/story MIP should be the first choice. It
should be noted that in this review, only studies inducing positive (elated)
and negative (depressed) mood were considered. Also, the words emotion,
emotional state, mood, and mood state are used as synonyms.
Conclusion
Several methods are effective in inducing different kinds of emotional
states. A rough distinction can be made between directly manipulating
experimental situations to produce real-life emotions (like the A-D method
of Levine and Burgess), and techniques that use imaginary or recollection
tasks (film fragments, music, autobiographical recollection etc). Philippot
(1993) states several advantages and disadvantages of both groups. The
direct manipulation of experimental situations, he claims, depends too

SWOV Publication D-2003-8 29
much on deceiving subjects, which is ethically and methodologically
problematic. He doesn't specify the methodological problems. But
moreover, the direction of the emotions is difficult to predict: it is likely that,
especially in the case of negative emotions, a mix of emotions will occur.
Film fragments, according to Philippot, if categorised a priori on the basis of
the emotion they supposedly evoke, can induce specific emotions.
However, from this study it appears that also in procedures using film
fragments, a mix of emotions may occur: it was especially difficult to find
fragments that evoke anger and disgust independently. A further
disadvantage of using video clips, is that the effects of emotional states are
likely to be mild, and it is not clear that the emotional states will last long
enough to have an effect on task performance.
Levine and Burgess induced specific emotions by experimental
manipulation. Although they did induce (as expected) a mix of negative
emotions, they were able to distinguish between them by asking subjects
what there primary emotion was. Then the subjects in the negative emotion
group were grouped based on this primary emotion and by doing so, the
effects of different emotions could be compared.
To establish the effects of emotion on driving performance, the most
promising way to induce emotions is by experimental manipulation of the
situation. This method will be most likely in inducing real emotions that last
throughout the whole task and will be most likely to affect cognitive
processing. Under the condition that situations are used that people most
probably encounter on the road every day, this procedure is also ethically
acceptable.
6.2. Measuring emotions
Once the emotion induction procedure has been carried out during the
experiment, manipulation checks should be carried out to see whether the
induction procedure did indeed produce the intended emotions. In other
words, the emotional state of the subject has to be measured. Methods to
measure emotions can roughly be divided into three categories: overt
behaviour, physiological measures, and self-reports.
6.2.1. Overt behaviour
Overt behaviour is concerned with observable actions or action tendencies.
Examples of this category are voice characteristics, facial expressions, and
body movements and positions.
Emotions expressed by voice can be inferred by judges with an accuracy
which is much better than chance, as was shown by Banse and Scherer
(1996). However, the differences in vocal patterns are often related to
arousal and not to the specific quality of the emotion. But Johnstone and
Scherer (2000) say that even though, until now, no clear acoustic patterns
of discrete emotions have been found, this does not mean that they don't
exist. The fact that people can recognise emotions so well from voices
means that there should be specific acoustic patterns. Johnstone and
Scherer give two reasons why these patterns have not been found clearly
until now. First, until now, only few acoustic parameters have been used.

30 SWOV Publication D-2003-8
Second, the emotional states have not been defined precisely enough. For
example, irritation and anger were seen as similar emotions with different
intensity and therefore given the same label, but they appear to have very
different acoustic patterns. The study by Banse and Scherer showed that
taking a wide range of acoustic variables, and clearly defining emotional
states, can clearly increase the discriminating power of acoustic patterns.
Recently, facial expressions of emotions are sometimes considered as
resulting from social motives rather than the experience of an emotion. A
Dutch newspaper cited from a study on professional bowlers' facial
expressions. Results showed that when the bowlers scored a strike, they
immediately felt happiness, but they didn't start smiling until they turned
back towards the audience. Facial expressions are in fact easy to
manipulate: people smile when they do not feel joy, and people are angry
but do not show it. However, facial expressions do seem to correspond with
other indicators of emotions, like self-reports and activity of the central
nervous system.
Several programs have been developed to code different facial
expressions, like MAX and AFFEX by Izard and FACS by Ekman (Oatley
and Jenkins, 1996). The coding is done after facial expressions have been
photographed or videotaped. Several facial muscle contractions receive a
coding, and each facial expression is a combination of several muscle
contractions. For example, a happy smile consists of contraction of the
muscles encircling the eye, contraction of muscles causing the corners of
the lips curl upwards, and relaxation of muscles leaving the teeth bare.
There is a procedure which is able to detect muscle activity which is so
subtle that it is not observable by the FACS and other coding procedures:
EMG, but this is considered a physiological measure so we will come back
to this issue later on.
It seems that body movements or positions, without extra information from
face or voice, do give some information about emotions. In a Japanese
study (Sogon & Masutani, 1989), subjects viewed actors who were
expressing an emotion from the back. They had to choose the emotion
which they thought the actor was experiencing from a list. Recognition was
52% for Americans and 57% for Japanese subjects. Some emotions were
better identified than others, such as sadness and fear.
Observation of overt behaviour or actions offers a lot of information for the
emotion researcher. Actions of avoidance, approach or attack, facial
expressions, crying, assuming a body position, all of these can tell a lot
about the particular emotion the person is experiencing. They are easily
observable. One important issue is that of interpretation. When using overt
behaviour as an indicator of emotion, it is always necessary to make an
interpretation of the internal processes. For example: when a car driver
sounds the horn, one might assume that the driver is angry but he or she
might also just be trying to warn someone.

SWOV Publication D-2003-8 31
6.2.2. Physiological measurements
We will restrict ourselves to the physiological measures that are most
frequently used. For more measures we refer to Chapter 3 from Frijda's
book ‘The Emotions’ from 1986.
Electrocardiogram
Several things can be measured by ECG. The two most common variables
are number of beats per time interval (heart rate) and the time between
each heart beat (IBI, inter beat interval).
There are numerous early studies in which emotionally loaded stimuli were
presented to subjects and the heart rate was recorded. A higher heart rate
was assumed to be related to higher arousal levels, which was thought to
reflect emotional experience. So, when the heart rate increased, emotional
experience was present, and when the heart rate stayed the same or
decreased, no emotional experience was present. In later studies, changes
in heart rate were thought to be related to specific psychological states.
Research of Ekman and colleagues (Ekman, Levenson and Friesen, 1983)
linked specific patterns of autonomic response to the experience of specific
emotions. They showed that the experience of disgust, happiness, and
surprise was accompanied by a low heart rate activity; and the experience
of anger, fear, and sadness was accompanied by a high heart rate.
However, unique heart rate patterns for anger and fear are unlikely, since
these emotions both require increased blood supply to the muscles (for
fighting in the case of anger and fleeing in the case of fear).
In a meta-analysis, Cacioppo et al. (2000) compared several studies
dealing with heart rate increases. The meta analysis showed that the heart
rate response is:
- larger in anger than in happiness;
- larger in fear than in happiness;
- larger in fear than in sadness.
Electrodermal activity
The electrodermal activity shows how well the skin conducts electricity, and
thus is a measure for imperceptible sweating. It is usually measured on the
palm of the hand or on the sole of the foot. There is a difference between
tonic and phasic changes in conduction levels. Tonic changes are gradual
and relatively long-lasting changes. Phasic changes are elicited by stimuli
or by activities of the subject. Phasic changes are usually referred to as
electrodermal response (EDR) or galvanic skin response (GSR).
Skin conductance is affected by respiration, temperature, humidity, age,
sex, time of day, season, arousal, and emotions. The measure is therefore
not very selective (De Waard, 1996). However, Ekman and colleagues
(1983) found support for the hypothesis that fear and disgust produce larger
skin conductance increases than happiness.
EEG (Brain activity)
EEG or electroencephalogram measures electrical activity in the brain.
Typically the following classification is made:

32 SWOV Publication D-2003-8
Delta waves (until 4 Hz) (sleep);
Theta waves (4-8 Hz) (decreased alertness);
Alpha waves (8-13 Hz) (relaxed wakefulness);
Beta waves (more than 13 Hz) (active wakefulness).
Under the influence of emotional or sensory stimuli, the energy in the EEG
decreases. This is called alpha blocking. However, it doesn't say anything
about the particular emotion a person is experiencing. Some evidence
suggests that the left anterior region of the brain is involved in approach
related emotions (e.g. anger), and the right anterior region is involved in
avoidance related emotions (e.g. fear).
EMG (muscle activity)
Facial electromyography (EMG) measures the electrical activity of facial
muscles. It is sensitive for muscle activity even when observable facial
expressions are not present. There are two facial muscles which are
important in measuring emotions: the corrugator supercilii (above the brow,
used in frowning) and the zygomaticus major (around the edges of the
mouth, which raises the lips to a smile). The EMG activity of the corrugator
supercilii increases when experiencing negative emotions. The EMG
activity of the zygomaticus major increases when experiencing positive
emotions.
As was said earlier, emotional experience is sometimes accompanied by
physiological change. Situations are possible in which people experience
an emotion but no physiological activity can be measured, like in sadness.
So physiological measures alone are not enough to establish whether an
emotion has occurred (but this is the case for the other measures as well).
One should always make an extra interpretation based on context,
self-report, or observations. Also, when physiological activity is observed,
this does not necessarily mean emotional activity. Physical or mental effort
also produces changes in physiology. So, body change is neither a
necessary nor a sufficient condition. And even when it is very likely that the
observed physiological activity is related to emotional state, it is hard to
establish which emotion the person is experiencing, just based on the
specific physiological symptom. Finally, for using physiological measures, a
lot of equipment is needed.
6.2.3. Self-report
There are several ways of collecting self-reports:
- Interviews: one has time to ask further and to get more context
information.
- Diaries: one gets information about how emotions and moods develop
over time.
- Questionnaires: one can ask a lot of questions in a limited time span.
- Scoring scales: one can, for example, ask people to press a scoring
button to score emotional state every minute or at several predefined
moments.
There are standard questionnaires available to measure distinct emotions,
such as degree of anxiety, anger, depression, and general sense of
well-being. Other questionnaires measure various mood states.

SWOV Publication D-2003-8 33
Self-reports are an important source of information, since they can provide
information that is not visible from other sources. No one can give a more
accurate account of personal experiences than the person himself. Self-
report may also give an explanation of one of the other variables observed
(like changes in physiology or behaviour). Using self-reports is a convenient
research method (one does not need complicated equipment). And until
now, the other two types of measures have not been capable of
discriminating sufficiently between different emotional states. For these
reasons, self-report is a commonly used method in emotion research.
Of course, when using self-reports, one has to be careful how to interpret
the results. Although this is true also for physiological measures and overt
behaviour measures, some specific issues for self-reports deserve
attention. Errors in memory might occur, especially when subjects are being
asked about emotions from a long time ago. Also, in some cases, the
issues of self deception and social desirability might be relevant, especially
when asking about negative emotions. People are often encouraged to
express positive emotions and discouraged to express negative emotions.
Finally, there might be individual differences in lexical meaning: What one
person means by the word 'happy' might be different from what another
person means by the same word.
Also, during the measurement, problems may occur. Emotions and moods
are easily affected by the environment. Just asking a question might induce
some kind of affective state. For example, one procedure for inducing a sad
mood in subjects, consists of a list of statements. For each statement, the
subjects is asked whether he agrees or disagrees. But all statements are
worded negatively, for example:
“I often feel that my life is worthless.”
“Sometimes things happen that I have no control of.”
This procedure is quite effective in inducing a negative mood state, even if
the person disagrees with all the statements. So, this example shows that
one should be very careful how to phrase the statements, since they might
well influence the current mood state just by asking. In some standardized
questionnaires, this problem is solved by reversing half of the statements,
for example in Spielberger’s Trait Anxiety Inventory (Spielberger et al.,
1970).

34 SWOV Publication D-2003-8
7. Research plans
In the previous chapters we have seen that emotions have an effect on
cognitive processing, and might thus influence driving behaviour. Still, the
relation between different emotions and task performance in traffic is not
clear. This was thought to be sufficient reason to start up a long term
project on emotions and task performance in traffic. The project was started
in January 2001 and will be finished in December 2004. The results of the
project will be published as a dissertation. In this chapter, we will describe
the plans for research on this topic.
Generally, four main questions can be distinguished in the project:
1. Which are the determinants of emotions in traffic?
2. To what extent do emotions bias cognition?
3. To what extent do emotions affect the selection of action?
4. To what extent do emotions affect driving performance?
The four questions are visualised in Figure 1. Based on the literature
reviewed in the previous chapters, it is hypothesized that emotions in traffic
are affected by task goal interruption or promotion, task demands, and the
extent of personal interaction (the box ‘person/situation’). Then, emotion is
thought to bias cognition and affect selection of action (questions 2 and 3).
These are supposed to affect task performance (question 4). The box ‘goal
shift’ refers to those instances when emotions are so strong that task
performance collapses completely. The goals are no longer related to the
driving task (driving safely and arriving at the destination). This is seen for
example in instances of extreme aggression, when people get so mad that
they stop the car and get out to attack another person.
When the four research questions are answered sufficiently, a link can be
made between emotions in traffic and traffic safety. Although it will be very
difficult (if not impossible) to link emotions to accidents, the results of the
experiments will most likely lead to new insights regarding emotions and
safe or unsafe behaviour. In the dissertation, special attention will be paid
to this particular topic.

SWOV Publication D-2003-8 35
Task goal
interruption/promotion
Emotion
Person/situation
Goal shift
Task performance
Task demands
Selection of action
Cognitive bias
Figure 1. Model of the four research questions, showing that emotions in
traffic are affected by several ‘boxes’.
We will now describe the experiments planned to answer the four research
questions. The first experiments are described in more detail than the later
experiments, because we would like to keep the possibilities on the exact
direction of the studies somewhat open still. Also the detailed planning of
later experiments depends partly on the results of previous experiments.
7.1. What are the determinants of emotions in traffic?
Although several studies focussed on determinants of anger in traffic,
research on other emotions in traffic is limited. This is true, as we have
seen, for the effects of emotions, but also the determinants of emotions in
traffic are unclear at this moment. In other areas than traffic, several
aspects have been shown to be important.
First, from appraisal theory, we know that goal congruent events lead to
positive emotions, and goal incongruent events lead to negative emotions.
But the goals in emotion research mean something different than goals in
traffic, which are much more related to the task at hand. Therefore it is
necessary to know if the interruption of these task goals induces the same
emotions as the interruption of more global life goals.
Second, studies in the area of stress have shown that high task demands
may lead to stronger or differen t emotions than low task demands. In the
area of traffic, one can imagine that a certain event does not raise much
emotion when task demands are low, but will lead to much stronger
emotions when task demands are high. Therefore, we want to answer the

36 SWOV Publication D-2003-8
question if emotions are stronger under levels of high task demands than
under levels of low task demands.
Third, it is generally thought that most emotions are caused by other
persons, or occur in social situations. Also in traffic research, it has been
shown that anger occurs most often when other road users are involved.
But the effect of other persons and the situation on experienced emotions
in traffic have not been studied systematically. Therefore, the third question
of this study is: do interpersonal events raise other or stronger emotions
than situational events?
A questionnaire study was carried out to answer these questions.
Respondents were presented with a number of traffic scenarios, that
differed for each of the following three factors: value of the event (goal
congruent vs. goal incongruent), task demand (high vs. low), and personal
interaction (personal interaction vs. no personal interaction). Then a list of
emotions was presented and respondents were asked to rate each emotion
on a scale from 1 to 5.
At the time of writing of this report, the results of this study are being
analysed. The results of the study will be published separately in an article.
7.2. To what extent do emotions bias cognition?
A large number of studies showed that emotion might cause biases in
cognitive processing. Studies showed, for example, effects on memory,
risk, attention, judgement, accuracy of performance, optimism etc. From a
traffic psychology point of view, especially the optimism bias (the extent to
which people believe positive things will happen to them and negative
things will happen to others) is interesting, for two reasons. First, emotions
are likely to affect the level of optimism bias, and second, the optimism bias
has shown to be important for traffic safety.
Experiment 2
A video-based study will be carried out in the laboratory. Subjects will first
be brought in a mild emotional state by an emotion induction procedure. No
strong emotions will be induced, because of ethical reasons, and also
because it has been shown that even mild emotional states have a
profound effect on cognitive processing. The final choice of emotions that
are relevant for traffic is partly dependent on the results of the first
experiment.
After the emotion induction procedure, subjects will be presented with video
fragments concerning traffic situations. The videos are recorded from the
field of vision of the driver, so that it seems for the person watching the
video as if he/she is behind the wheel him/herself. The use of video
fragments is a good method, first because the validity has been shown
(Horswill and McKenna, 1999), second because it creates a controlled
enough environment to manipulate emotions, and third because the
situations are more realistic than the pictures in a simulator are.

SWOV Publication D-2003-8 37
Fragments will differ on following distance to the lead car. A total number of
12 fragments will be shown in random order to the subjects. After viewing
each fragment, the subject is asked several questions designed to measure
optimism bias. Also, questions will be asked to measure illusion of control
(the extent to which people believe they have control over the situation),
since it is believed to be related to optimism bias (DeJoy, 1989).
After rating the fragments, the subject will be asked to fill in three short
questionnaires, one is an emotion manipulation check, the second is
Spielberger’s Trait Anger Questionnaire (Spielberger et al., 1983), and the
third is Spielberger’s Trait Anxiety Questionnaire (Spielberger et al., 1970).
7.3. To what extent do emotions affect choice of action?
Apart from biases in cognitive processing, emotion may have an impact on
the choice of action. Several studies showed a relationship between
emotions and risky decision making. As risk perception, the selection of
safe and unsafe courses of action are very important for traffic safety.
Therefore this experiment will focus on the effect of emotions on the
selection of more and less risky actions.
Experiment 3
Roughly the same method will be used as in experiment 2. Subjects in
different kinds of emotional states will watch a series of video fragments
where a car is driving on different road types and traffic conditions. The
videos are recorded from the field of vision of the driver, so that it seems for
the person watching the video as if he/she is behind the wheel him/herself.
But instead of making estimates of risk or measuring optimism bias, in this
experiment, subjects are asked to make choices. After each video
fragment, the screen is put on ‘still mode’ and two or more options are
presented to the subjects, including more and less risky options. Again,
after watching the video's, the subjects will answer the emotion
manipulation check questionnaire and Trait Anger and Trait Anxiety
Questionnaires.
7.4. To what extent do emotions affect actual driving performance?
Possible effects of emotions on cognitive processing and selection of action
are most likely to have an effect on actual driving performance as well.
Therefore, in the fourth experiment, we will investigate if people in different
emotional states perform differently in the driving task.
Experiment 4
Subjects will be brought in an emotional state before participating in a test
ride in an instrumented car. During the test ride, subjects are either given
specific instructions about how to drive (what speed or what distance to the
lead car) or are instructed to drive as they normally would. Driving
behaviour is measured, and the focus is on cognitive biases and on choices
of action. Thus it can be seen if the results of studies 2 and 3, which were
carried out inside the laboratory, extend to a real life driving situation. After
the test drive, questions will be asked to measure the emotional state of the

38 SWOV Publication D-2003-8
subject. This is done to check if the manipulation has worked throughout
the experiment. Induced emotional states usually don’t continue during
longer periods of time, therefore the test drive should not be very long.
7.5. “Experiment 5"
As said earlier, sometimes emotions can be so strong that they disrupt task
performance completely. This has been seen in incidents concerning
extreme anger and aggression, but also other emotions can have this
effect, for example, someone with fear of driving can be so scared that it is
impossible to continue driving and the car is stopped on the shoulder of the
highway.
A number of earlier collected descriptions of aggressive incidents will be
qualitatively studied. This will provide insights in the processes that lead to
the disruption of task performance by extreme emotion, in this case anger.
Examples of disruption of task performance caused by anger:
“Me and a friend in my car. Argument with other road user about his way of
(dangerously) overtaking. Making gestures and putting the cars on the
roadside, a small physical fight. Pushing, black eye, kicking the car etc. “
“A car was driving against the mirror of my boyfriend’s car. It was the fault
of the other guy and he still continued driving further. Then my boyfriend got
angry and chased him. It didn’t take long. When we were standing still, my
boyfriend had an argument with him and kicked against his car.”
“In the early morning I was intending to drive away from the parking spot in
my street, when a car stopped right there, so I couldn’t drive away. When I
asked him to move a few metres to give me some space, he refused. Then
I got very angry, got out of the car, started yelling at him, and slammed his
car door and window.”
7.6. Conclusions
With the experiments we described above, we hope to gain knowledge
about both the determinants of emotions in traffic, and the effects of
emotions on task performance in traffic. This knowledge is needed, for
several reasons. First, on a more general level, studies on the relation
between emotions and task performance are limited. With this research we
hope to contribute to the discussion on emotions and their beneficial or
harmful effects.
Second, the knowledge is important for the area of traffic safety. If one
knows which factors might lead to strong emotions, and if one knows how
these emotions affect task performance, possibly in a negative way, then it
might be possible also to say something about the relation between
emotions and traffic safety. Also, measures can be developed to prevent
these harmful effects.

SWOV Publication D-2003-8 39
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