The effects of action video game play on vision and attention

Abstract

Practice and training on a task almost invariably results in improved performance, but training gains rarely transfer to novel or even similar untrained tasks. Limited transfer of training is one of the most pervasive findings in the learning and training literature. However, exciting data suggest video game training, specifically action video game training, is a rare exception to this general rule and that action games can improve a variety of perceptual and cognitive abilities. This chapter reviews the evidence that action game training can improve a variety of visual and attentional abilities, including positive effects of game play on the fundamental building blocks of vision. In a very real sense, these findings suggest that action gamers see the world in a way that is different from non-gamers. Other findings suggest that action gamers extract information in the visual periphery more efficiently and are better able to cope with peripheral visual distraction. While these results have generated a lot of attention and enthusiasm, we outline a number of reasons why these findings should be considered tentative, but worthy of further exploration. We conclude this chapter by discussing critical unanswered questions and future directions, including the possibility of game training as a means to address specific visual and cognitive deficits, and the possibility of game benefits extending beyond laboratory tasks of perception and cognition to safety-critical tasks such as driving.

Full text

Action Games and Attention 1
Running Head: THE EFFECTS OF ACTION GAMES ON ATTENTION
The Effects of Action Video Game Play on Vision and Attention
Timothy Wright
Daniel P. Blakely
Walter R. Boot
Department of Psychology,
Florida State University
Address correspondence to:
Walter R. Boot
Florida State University
Department of Psychology
1107 W. Call Street
Tallahassee, FL 32306-4301
Phone: (850) 645-8734
Fax: (850) 644-7739
boot@psy.fsu.edu

Action Games and Attention 2
Abstract
Practice and training on a task almost invariably results in improved performance, but
training gains rarely transfer to novel or even similar untrained tasks. Limited transfer of
training is one of the most pervasive findings in the learning and training literature.
However, exciting data suggest video game training, specifically action video game
training, is a rare exception to this general rule and that action games can improve a
variety of perceptual and cognitive abilities. This chapter reviews the evidence that
action game training can improve a variety of visual and attentional abilities, including
positive effects of game play on the fundamental building blocks of vision. In a very real
sense, these findings suggest that action gamers see the world in a way that is different
from non-gamers. Other findings suggest that action gamers extract information in the
visual periphery more efficiently and are better able to cope with peripheral visual
distraction. While these results have generated a lot of attention and enthusiasm, we
outline a number of reasons why these findings should be considered tentative, but
worthy of further exploration. We conclude this chapter by discussing critical
unanswered questions and future directions, including the possibility of game training as
a means to address specific visual and cognitive deficits, and the possibility of game
benefits extending beyond laboratory tasks of perception and cognition to safety-critical
tasks such as driving.

Action Games and Attention 3
Introduction
A great deal of research has focused on the potentially negative impact of video
games on players, especially games involving violent content (see Anderson & Bushman,
2001; Ferguson & Kilburn, 2009; Sherry, 2001 for discussion). The main question of this
controversial line of research has been whether violent video games play a causal role in
increasing aggression and violent behavior. While this debate continues to rage, exciting
research has also recently begun to explore the potentially positive impact of video game
play on a variety of perceptual and cognitive skills. A number of studies seem to indicate
that video game play, especially fast-paced action video game play, can result in vastly
superior visual and attentional abilities. This is surprising given that previous efforts to
train generalizable perceptual and cognitive improvements have almost universally failed.
In this review we discuss basic principles of learning and training, how action video
game training appears to be an exception to these general principles, provide a critical
view of the current gaming and cognition literature, and finally, discuss future directions
and unanswered questions.
Training and Transfer of Training
What is most surprising and noteworthy about recent claims that video games can
improve a host of abilities, and performance on tasks other than the games themselves, is
that these claims contradict established beliefs about the limits of training. In general,
experience, practice, and training can greatly improve an individual’s performance on a
specific task or domain of tasks. For example, with directed practice activities an
individual can progress from novice to elite status in domains such as chess, sport,

Action Games and Attention 4
medicine, and music (see Ericsson, Charness, Feltovich, & Hoffman, 2006 for review).
In fact, there are few tasks that do not benefit from practice. However, gains obtained
during practice are specific to the practiced task. That is, performance gains do not fully
transfer (or transfer at all) to unrelated tasks or even tasks very similar to the trained task.
This general rule of “limited transfer of training” spans across a number of domains of
learning from low-level perceptual learning to the development of problem solving and
decision making skills.
In terms of improvements to basic visual abilities, observers can easily learn how
to detect and discriminate visual targets more quickly and accurately with experience and
these improvements can be long-lasting (Goldstone, 1998). However, a number of
studies find that perceptual learning gains are extremely specific; training to detect
specific targets does not benefit the detection of similar targets and training gains may not
transfer from one eye to the other or even to different retinal locations within the same
eye (Ball & Sekuler, 1982; Fahle & Morgan, 1996; Fiorentini & Berardi, 1980; Shiu &
Pashler, 1992). Higher level cognitive processes such as problem solving also appear to
suffer from similar limits. For example, learning computer programming requires an
active process of problem solving, but acquired problem solving skills do not transfer to
other tasks (Pea & Kurland, 1984; Salomon & Perkins, 1987). Furthermore, learning the
solution to a problem does not guarantee that the solution will be applied appropriately to
similar problems in the future (Catrambone & Holyoak, 1989; Gick & Holyoak, 1980).
From low-level perceptual learning to higher level cognition, the general theme that
emerges again and again is that it is rare for experience or training to improve
performance on a wide-range of tasks.

Action Games and Attention 5
Limited transfer of skill is echoed in the study of expertise and exceptional
performance. For example, it is a common finding that chess experts can quickly encode,
and later perfectly recall all the positions of each piece on a chess board taken from a
random game. However, when chess positions do not come from a game, but are
generated randomly, the memory of chess experts is no different from novice players
(Chase & Simon, 1973, Gobet & Simon, 1996). In general, the superior skill of the
expert comes from cognitive and physiological adaptations to the demands of a specific
task or set of tasks (Ericsson & Lehmann, 1996). When the demands of a task are
changed such that they no longer match the conditions under which expertise was
developed the performance of experts can drop to unexceptional levels.
These few examples serve to highlight learning specificity. What they suggest is
that if there are multiple tasks one wishes to improve performance on, each of these tasks
must be trained separately. A general assumption of “brain fitness” interventions,
including software programs currently being marketed to older adults as a way to address
age-related cognitive decline, is that perception and cognition can be improved generally.
Namely, they can train basic abilities that can then improve performance on a wide-range
of tasks. However, even within this literature, results are fairly mixed regarding the
efficacy and generalizability of brain fitness training (Hertzog, Kramer, Wilson, &
Lindenberger, 2009). As we will discuss, video games appear to be a salient exception to
this general rule of limited transfer of training. Action game training has been
demonstrated to improve a number of visual abilities, and to have a substantial effect on
visual attention. Given that visual attention is one of the cognitive constructs most

Action Games and Attention 6
influenced by action video game play, we briefly discuss what visual attention is, the
function it serves, and its relationship to awareness and conscious visual perception.
Visual Attention Primer
The complex environments we navigate every day contain far too much
information for the visual system to process all at once. In order to function effectively
in these environments we need to selectively process the vast amount of information with
which we are bombarded. Scene and object perception, navigation, visual search, as well
as a host of other activities rely on mechanisms of visual attention to direct limited
processing resources to task-relevant information while discouraging the processing of
task-irrelevant information. The focus of attention has been conceptualized as a
“spotlight” or “zoom lens” (Ericksen & Yeh, 1985; Posner, Snyder, & Davidson, 1980).
Information falling within the spotlight or at the center of the zoom lens is processed,
while information outside is not processed or processed to a lesser extent. The spotlight
is moved or the zoom lens is refocused until the information required to complete a task
is extracted.
Attention modulates what information is consciously available to act upon and
what information is encoded into memory to be acted upon later. Some have gone as far
to say that without attention there is no conscious perception of the visual world (Mack &
Rock, 1998). Since attention determines what is perceived and remembered it is a
fundamental determinant of human cognition and behavior. As such, researchers have
extensively investigated the factors that influence how attention is deployed. A large
body of research suggests that attention can be intentionally deployed to only the most

Action Games and Attention 7
relevant objects and locations within a scene, reducing the processing of irrelevant
information and facilitating goal-oriented action (i.e., attention can be allocated in a “top-
down”, or goal-directed manner). For example, when searching for your car in a parking
lot you might limit your search to cars sharing the same color as your car. However, if
the allocation of attention were solely determined by the current goal of an organism,
important environmental changes requiring immediate action might go unnoticed (e.g., a
car in the parking lot suddenly looming towards you). In these cases, it is imperative for
attention to be “captured” by events irrelevant to the current goal but of importance
nonetheless (i.e., attention can be driven by “bottom-up”, or stimulus-driven forces).
However, we also don’t want attention to be continuously allocated to irrelevant changes
in the environment. In order for the attention system to operate effectively, the need for
goal-directed attention against must be weighed against the importance of interruption by
potentially important events (Conner, Egeth, & Yantis, 2004).
According to recent studies of the effects of video games on perception and
cognition, video game play can fundamentally alter the dynamics of visual attention,
implying that gamers are much better equipped to deal with the complex visual
environments we navigate every day. Specifically, according to these studies, fast-paced
action video game play has a large impact on the efficiency with which attention can be
allocated across both time and space. Next, we focus on the many influences of action
video game play on visual attention.
Action Video Games and Attention

Action Games and Attention 8
Interest in the effects of video game play on basic perceptual and cognitive
abilities is not a recent phenomenon (e.g., Clark, Lanphear, & Riddick, 1987; Gagnon,
1985; Greenfield, Brannon, & Lohr, 1994; Greenfield, DeWinstanley, Kilpatrick, & Kay,
1994). However, a recent surge in interest in the potential effects of video game play
began with a highly influential paper by Green and Bavelier (2003) demonstrating a link
between superior attentional skills and action video game play. Initially, the performance
of action gamers was compared to non-gamers on a number of laboratory tests measuring
the flexibility of visual attention across space and time. An individual was classified as
an action gamer if, over the past six months, he spent at least one hour playing action
video games a day, for a minimum of four days a week (note that cross-sectional
gamer/non-gamer comparisons in this and other studies frequently included only males
due to the relative paucity of female action gamers). Action gamers frequently reported
playing first-person shooters such as Halo, Half-Life, and Counter Strike, in addition to
other fast-paced action and racing games including Grand Theft Auto 3, Crazi Taxi, and
Super Mario Kart. Non-gamers reported minimal game experience over the past six
months. When compared to non-gamers, an action gamer advantage was observed in the
Useful Field of View task, a measure of peripheral attentional processing, the attention
blink task, a measure of the temporal resolution of attentional processing, and an
enumeration task that measured observers’ capacity to attend to multiple objects.
Additionally, action gamers demonstrated increased distraction by irrelevant peripheral
information in a visual search task. Green and Bavelier interpreted this as an action
gamer advantage: action gamers were so efficient at performing the search task, they had
spare resources to attend to and processes task-irrelevant information. Thus, across a

Action Games and Attention 9
number of tasks tapping visual and attentional abilities, action gamers far outperformed
non-gamers.
Of course, observed ability differences between action gamers and non-gamers do
not necessarily mean that action game play caused these differences. Directionality and
third-variable problems (discussed in detail later) are inherent to cross-sectional studies
comparing action gamers and non-gamers and limit the strength of conclusions that can
be drawn from such studies. To provide more definitive evidence that action video game
play causes superior abilities, something akin to a clinical trial is necessary in which
individuals are randomly assigned to play an action video game or to a control group, and
abilities are assessed before and after game training. This was the next approach taken by
Green and Bavelier (2003). Non-gamers (this time both men and women) were recruited,
and were either asked to play a fast-paced action game (Medal of Honor) or a non-action
puzzle game (Tetris) for 10 hours. After just 10 hours of game training, participants in
the action game group demonstrated significant gains on the same tasks measuring the
spatial and temporal limits of attentional processing, suggesting that action video game
experience plays a causal role in producing superior abilities.
This initial report of the effects of action video game play on attentional abilities
generated a flurry of follow-up studies. As discussed previously, attention acts to select
which objects in the environment receive processing priority and which are ignored.
However, attention is limited in the number of objects (or locations) it can select at any
one time, with this limit corresponding to three or four objects (e.g., Alvarez &
Franconeri, 2007; Pylyshyn, 1989; Xu & Chun, 2009). In follow-up reports, action
gamers demonstrated an advantage in multiple object tracking, or the ability of observers

Action Games and Attention 10
to mentally keep track of multiple fast-moving objects (Green & Bavelier, 2006a).
Action gamers and non-gamers trained to play action games tracked greater numbers of
objects more accurately. In an enumeration task, observers are asked to quickly and
accurately report the number of objects briefly flashed on screen. Observers are typically
very accurate as long as the number of objects is less than about four. Action gamers,
however, showed little cost in terms of accuracy for up to five objects. Thus action video
game play appears to be associated with the ability to attend to and apprehend a larger
number of objects simultaneously.
The balance between top-down, or goal-directed control of attention, and bottom-
up, stimulus-driven control is one of the primary issues under debate in the attention
literature. That is, how much of our allocation of attention is under conscious control,
and how much is driven by the external world? There is ample evidence to suggest that
salient or unique visual features or events can attract attention in the absence of a top-
down goal to attend to them. Attention appears to be drawn to these features in a
bottom-up, stimulus-driven manner. Much of this evidence comes from attention capture
literature. In these studies participants are given a clearly defined search goal. However,
on some percentage of trials a salient but irrelevant feature is added to the display to
observe its effect on performance (i.e., whether it induces distraction). In the additional
singleton paradigm developed by Theeuwes, participants may be given the goal of
finding a green circle among green squares and must indicate the orientation of the line
within it. However, on some trials one of the squares is red. A typical finding is that
even though participants know the target is always the green circle and the red item is
never relevant to their task, participants are slower to find the target when the red item is

Action Games and Attention 11
present (Theeuwes, 1992; Theeuwes, 1994). This slowing is taken as evidence that
attention is captured by the uniquely colored item. Chisholm, Hickey, Theeuwes, &
Kingstone (2010) examined attention capture effects in samples of action video game
players and non-gamers using this attention capture paradigm. Not only were video
gamers on average faster at finding the target, but action gamers demonstrated a
substantially smaller attention capture effect. This was interpreted by the authors as
evidence that action gamers can overcome the distracting effect of salient but irrelevant
information through enhanced top-down attentional control (but see Green & Bavelier,
2003; 2006b for evidence that in some situations, action gamers can be more distracted
by irrelevant information).
In sum, there is evidence that action video game players, and non-action gamers
trained to play action video games, demonstrate a number of superior attentional abilities.
These include a greater capacity to attend to multiple objects simultaneously, to attend to
multiple targets within short periods of time, to distribute attention widely to detect
peripheral targets, and in some instances, a greater ability to resist distraction. These
findings are surprising and noteworthy for several reasons. First, measures of attentional
control were visually dissimilar and required different responses compared to the action
games themselves, indicating a breadth of transfer rarely seen in the skill acquisition and
training literature. Second, training studies demonstrated significant improvement after
relatively short periods of training (from 10-50 hours). However, the breadth of training
is claimed to be even wider than described, with action video games improving numerous
other abilities.

Action Games and Attention 12
Action Video Game and Other Abilities
Low-Level Vision
Not all action game effects can easily be explained by enhanced attentional
control. For example, Green and Bavelier (2007) examined visual acuity thresholds of
action video game players and non-players and found an action game advantage. Similar
effects were observed in non-gamers trained to play action video games. Li et al. (2009)
also found action video game play to be associated with enhanced contrast sensitivity, or
ability to pick up visual detail. Finally, Li et al. (2010) demonstrated that basic dynamics
of low level vision are influenced by action video game play. When two similar images
are presented one right after another, images tend to “mask” one another, reducing
visibility. Li and colleagues observed that this masking effect was much reduced in
action video game players, and after action video game training.
Executive Control
In addition to thinking about attention to objects and locations in the visual field,
we can also think about attention to tasks. We increasingly face multi-tasking
environments as the pace of technology increases. How do we deal with managing
multiple simultaneous tasks and goals, especially in cases in which we must rapidly
switch from one task to another? This ability to maintain multiple goals and juggle
between them has been referred to as executive control, and the task-switching paradigm
has been one of the most used experimental paradigms to understand this ability (Pashler,
2000). A typical task-switching paradigm might present participants with a series of
random digits and ask them to judge whether each digit is high or low, or odd or even as
quickly and as accurately as possible. On each trial, the task which participants are asked

Action Games and Attention 13
to perform is unpredictable; participants may be asked to perform the same task they
performed on the previous trial or the other task. Critically, there is an observed cost on
“switch” trials. Participants are slower and less accurate when the task they are asked to
perform is different compared to the previous trial, and this cost reflects the difficulty of
keeping multiple goals in mind and switching between them. In a cross-sectional study
of action gamers and non-gamers, Boot et al. (2008) found that switch costs were
substantially reduced for action video gamers. Similar effects were reported by Andrews
and Murphy (2006), Karle, Watter, and Shedden (2009) and Colzato and colleagues
(2010). In general, action game play appears to be associated with greater flexibility with
respect to maintaining and switching between goals.
Commercially Available “Brain Fitness Games” and Cognition
Recently, a number of commercially available non-action video games have been
developed with the purpose of improving cognitive abilities. For example, Nintendo
advertises Big Brain Academy as a game that “trains your brain with a course load of
mind-bending activities across five categories: think, memorize, analyze, compute, and
identify.” Players are assigned a “brain weight” score based on their performance, with a
higher brain weight corresponding to better performance. Nintendo states that these
puzzles are “designed to help you increase the weight of your mighty brain”. Brain Age,
another game by developed by Nintendo specifically marketed to aging adults, makes the
claim that players can “train their brain in minutes a day”. Like Big Brain Academy,
players are initially assigned a performance score known as their “brain age”. This score
is based on players’ speed and accuracy on a number of simple reaction time and
perceptual tests. As players train on these tasks their “brain age” score decreases.

Action Games and Attention 14
However, despite these apparently strong claims, very little is claimed regarding how an
increased “brain weight” or a decreased “brain age” might transfer to tasks other than the
specific tasks within the games. In fact, the reaction time, logic, and perceptual training
offered by these games bears a striking resemblance to the training tasks of the ACTIVE
trial (Ball et al., 2002) which produced no meaningful transfer to real-world tasks.
A recent study conducted by Ackerman, Kanfer, & Calderwood (2010) assessed
the ability of Big Brain Academy to address cognitive declines associated with aging. In
a sample of participants from 50 to 71 years of age, participants received two training
interventions. One intervention involved 20 hours of Nintendo’s Big Brain Academy, a
game specifically marketed as a way to improve cognition. The other intervention
involved 20-hours of directed reading, with readings covering a range of topics from
health, to the environment, to technology. Multiple measures of cognitive performance,
including measures of fluid intelligence and processing speed, were taken before and
after each training intervention. However, no game training benefit was observed,
suggesting broad training benefits may be restricted to more complex visually and
attentionally demanding video games (Basak, Boot, Voss, & Kramer, 2008).
Criticisms of the Game and Cognition Literature
Despite a number of positive findings in favor of the association between action
video game play and superior perceptual and cognitive abilities, some researchers have
challenged the idea that there is a causal link between gameplay and cognition. This
skepticism comes from a number of failures to replicate previous video game results and
from a critical analysis of the methods and results of cross-sectional and game training

Action Games and Attention 15
studies (see Boot, Blakely, & Simons, 2011 for an in-depth analysis). While these
methodological issues and failures to replicate do not necessarily disprove a link between
action gaming and superior abilities, they suggest that more research is necessary before
strong conclusions can be drawn, and that video game benefits may be more specific than
previously thought.
Failures to Replicate Game Effect
Boot et al. (2008) conducted a close replication of Green and Bavelier’s (2003)
original study, which included additional measures of attention, memory, and executive
control. The same training games (Medal of Honor, Tetris) were tested, in addition to a
real-time strategy game called Rise of Nations. Boot and colleagues expected, based on
previous findings, that action video game play would result in substantial improvements
in terms of visual and attentional abilities (particularly for the same measures assessed by
Green and Bavelier, namely Useful Field of View, Attention Blink, and Enumeration).
Furthermore, given the real-time strategy game’s emphasis on planning, goal-
maintenance, reasoning, and spatial memory, the authors expected a number of
improvements related to these abilities following training with this genre. However,
despite testing a sample twice as large as the sample studied by Green and Bavelier
(2003), and training participants for twice as long (20 hours vs. 10 hours), no action game
effects were observed on any of the outcome measures. Additionally, the real-time
strategy game resulted in no differential improvement compared to the action game
(Medal of Honor), puzzle game (Tetris), or no-training control group. In fact, the only

Action Games and Attention 16
training effect observed was extremely specific; participants who received 20 hours of
Tetris training improved on a measure of mental rotation (see De Lisi & Wolford, 2002;
Sims & Mayer, 2002 for similar findings). Cross-sectional comparisons between action
gamers and non-gamers revealed no effect of game experience on the abilities Green and
Bavelier (2003) originally assessed. Frequent action gamers did, however, exhibit better
multiple object tracking, visual short-term memory, and task-switching ability, but since
superior abilities could not be engendered by game training, Boot and colleagues
interpreted results as being just as likely to reflect pre-existing group differences between
action gamers and non-gamers.
A number of other studies also seem to call into question or demonstrate the limits
of action video game experience. One such study was conducted by Castel, Pratt, &
Drummond (2005). In two paradigms measuring visual attention, habitual action gamers
demonstrated faster responses compared to non-gamers, but otherwise the performance of
action gamers and non-gamers was extremely similar. Castel and colleagues attributed
the action gamers’ advantage not to better visual/attentional skills, but to gamers’
superior ability to quickly learn and process stimulus-response mappings (i.e.,
understanding which button to press when they saw a particular visual target). While
interesting on its own, this explanation is fundamentally different compared to proposed
changes to the building blocks of visual experience. Similar to Boot et al. (2008),
Murphy and Spencer (2009) assessed the skills of action video game players and non-
gamers on two of the same attention tasks used by Green and Bavelier (2003) and found
only a minimal gamer advantage in the Attention Blink task, and no difference in the
Useful Field of View task. Finally, one of the most exciting findings demonstrated by

Action Games and Attention 17
Green and Bavelier (2003; 2006a) was that habitual action gamers appeared to have more
attentional resources to draw upon compared to non-gamers. As previously mentioned,
irrelevant visual information can have a larger effect on the performance of action gamers
compared to non-gamers during visual search, indicating additional attentional resources
available to gamers to process both relevant and irrelevant information. However, Irons,
Remington, and McLean (2011) could not replicate this finding after multiple attempts,
sometimes finding the complete opposite result: evidence for action gamers having fewer
attentional resources.
Methodological Issues in Previous Game Studies
Boot, Blakely, and Simons (2011), in a critical review of recent studies
investigating the effects of action video game play on perceptual and cognitive abilities,
highlight a number of methodological problems that call into question the conclusion that
action video game play can improve a variety of perceptual and cognitive abilities.
While converging evidence would seem to favor the existence of game effects (but note
failures to replicate above), Boot and colleagues argue that the pervasiveness of these
methodological flaws alone is enough to raise serious doubts regarding the potential
benefits of game play.
For example, many studies arguing for the benefits of video games use cross-
sectional designs to contrast the performance of gamers and non-gamers on measures of
perception and cognition (e.g., Andrews & Murphy, 2006; Bialystok, 2006; Boot, et al.,
2008; Chisholm, et al., 2010). These comparisons alone provide no direct evidence for

Action Games and Attention 18
game benefits because other factors could contribute to observed differences. For
example, people may become gamers because they have superior attention, perception,
and motor control; those superior abilities might contribute to the desire to play games in
the first place. These third variable and directionality critiques are obvious to most
scientists who know that correlation is not the same as causation, even if it is less well
understood by public consumers of scientific findings. Some studies have tried to
compensate for the shortcomings of expert/novice comparisons by arguing that even
among gamers, the amount of action game experience correlates with performance on
cognitive tasks (Donohue, Woldorff, & Mitroff, 2010). Such findings show that gaming
and cognitive skills are linked systematically, however they provide no evidence that
gaming causes differences in skill. Individual differences in basic abilities might
influence the degree to which participants enjoy different gaming genres or the amount of
time they spend playing specific game genres and should not be mistaken for a dose-
response methodology in which the amount of play is systematically manipulated to test
for cause.
In addition to the limits of cross-sectional comparisons, Boot and colleagues
question whether participants’ expectations regarding how they should perform, induced
by the manner in which they were recruited to participate, might explain some or all of
the differences between gamers and non-gamers in cross-sectional studies. The most
efficient way to recruit gamers and non-gamers, of course, is to post signs and flyers
around campus either seeking individuals with action video game expertise or no gaming
experience. However, overt recruitment of “experts” may provide a powerful cue to
gamers regarding how they are expected to perform in the laboratory on difficult, game-

Action Games and Attention 19
like computer assessment tasks. Expectation and motivation effects have been found to
improve abilities as fundamental as visual acuity (Langer et al., 2010), thus it is plausible
that the way in which gamers and non-gamers are recruited has some influence on their
performance. Unfortunately, the large majority of studies offer no details regarding how
participants were recruited, thus the degree to which demand characteristics drive game
effects is unknown and is likely a fruitful and important topic of future research.
Training studies in which non-gamers are given action game experience to test
whether action games specifically improve perceptual and cognitive abilities, in principle,
can overcome the limitations of cross-sectional studies. However, an active control
group, one in which participants receive a fake or “placebo” treatment, is crucial in terms
of the validity of the conclusions that can be drawn from any training study. Without an
adequate control group, it is uncertain whether the experimental group improved due to
the treatment they received (action game experience), or due to the expectation that they
should improve after receiving any kind of treatment (i.e., a placebo effect). Popularized
by Green and Bavelier (2003; 2006a; 2006b; 2007), the use of an active control group
that also played a video game, but not an action video game, is a particularly innovative
and clever way to address potential placebo effects. However, Boot and colleagues
question whether a fast-paced action game such as Unreal Tournament (an action game
commonly used in game studies) produces the same expectation of improvement
compared to much slower-paced games such as The Sims (a common control treatment).
If participants who receive training on fast-paced visually and attentionally demanding
tasks are more likely to believe that the intervention they received is capable of
improving performance on fast-paced visually and attentionally demanding assessment

Action Games and Attention 20
tasks, this is important information to consider in interpreting game training studies. So
far, no published study has examined participants’ expectations in any video game
training study, and the degree to which different games produce different expectations is
a major potential concern.
In addition to these primary critiques, Boot, Blakely, and Simons (2011) raise a
number of other questions regarding the interpretation of game effects. Most gaming
studies claim that video game experience changes fundamental abilities and cognitive
mechanisms. However, as little as one hour of game play can significantly influence
performance on cognitive and psychomotor tasks, raising the question of whether basic
abilities are changed or whether game play affects the way participants approach tasks
(i.e., strategy). Nelson and Strachan (2009) had participants play a puzzle or action game
for one hour. They then assessed performance on tasks of psychomotor speed/accuracy
and visual processing. The action game induced fast, less accurate performance and the
puzzle game induced more accurate, but slower performance. If such strategic shifts can
be observed after one hour, their role after dozens of hours of game play may be even
stronger. In a cross-sectional comparison of gamers and non-gamers, Anderson,
Bavelier, & Green (2010) observed similar trade-offs across a variety of cognitive tasks.
Performance changes in training studies and performance differences in cross-sectional
studies need not result from changes in basic abilities; strategy, expectations, and
motivation of participants play an important role (Clark, Fleck, & Mitroff, 2011).
While a number of concerns are raised regarding the state of the action video
game literature, it is still possible to be optimistic regarding the effects of games on
cognition. However, studies must be conducted with more rigor in order to fully

Action Games and Attention 21
understand the potential of game training. Boot, Blakely, and Simons (2011) propose a
number of guidelines to allow for more definitive tests of the effects of action video game
play on perceptual and cognitive abilities. These include 1) a full reporting of all study
methods, including how participants were recruited, 2) whenever possible, covert
recruitment procedures should be implemented in cross-sectional studies so that gamers
and non-gamers have no idea that they have been selected based on their gaming history,
3) process tracing approaches such as the collection of “think aloud” protocols (Ericsson
& Simon, 1993) and eye tracking data can be used to help determine whether
performance improvements result from a change in basic abilities or a change in strategy,
and 4) all training studies should assess the degree to which participants expect to
improve after receiving different types of game training. Whenever possible,
expectations should be equated. By adopting these best-practices, researchers can more
accurately judge the presence and size of action video game effects on abilities.
Future Directions and Unanswered Questions
So far we have discussed a number of studies concluding that action video game
play can improve a variety of abilities. One future direction, as we point out, it to explore
these effects using more rigorous methods to understand the potential influence of
motivation and expectations in producing game effects. If game effects represent true
ability changes, other important questions relate to understanding the components of
action games that produce observed improvements, how to define what an action game is,
and finally, whether we can expect action video game effects to transfer beyond simple
laboratory tasks.

Action Games and Attention 22
What is the “active ingredient” contained within action video games responsible for
broad transfer of training and improved general abilities?
Action video game training diverges from other forms of training in that skills
acquired during game play transfer to other visually and attentionally demanding tasks.
What makes action video game training so different from our non-game experiences and
other perceptually and cognitively demanding tasks? While it is interesting and
important to catalogue the various changes associated with action video game play, a goal
of future research needs to be to better understand how action games produce these
effects. That is, what is the “active ingredient” (or ingredients) contained within action
video games that engender such broad transfer?
Video games in general appear to incorporate several elements associated with
rapid skill acquisition and the development of generalizable skill. These include training
variability (practicing the same skill under varied conditions), performance feedback, and
adaptive difficulty (Kramer, Larish, & Strayer, 1995; Schmidt & Bjork, 1992). It has
also been suggested that experience with games that feature multiple overlapping,
attentionally-demanding components trains the efficient allocation of cognitive resources,
and that it is this resource management skill that transfers to other tasks (Gopher, Weil, &
Bareket, 1994; Gopher, Weil, & Siegel, 1989). The emotional and motivational
components of game play, absent in many other training tasks, are also hypothesized to
play an important role in producing efficient learning and transfer (Green, Li, & Bavelier,
2009). Finally, broad transfer to many different tasks has been attributed to game-
induced improvements in processing speed and the fine-tuning of general learning
mechanisms (Dye, Green, & Bavelier, 2009; Green, Pouget, & Bavelier, 2010). From

Action Games and Attention 23
this abbreviated list of proposed critical game elements and proposed mechanisms on
which they act, it is clear that much more study is necessary before we will be able to say
with certainty how action video games are able to improve the performance of so many
different tasks.
One of the main challenges faced by researchers in this field is the complexity of
modern action games. In typical studies comparing action and non-action game training,
there are literally hundreds of game aspects that differ between training interventions.
For example, action game training interventions almost exclusively feature games with an
ego-centric, first-person point of view, while this is not true of non-action video game
interventions. This may be one of the crucial differences between action games and non-
action games tested responsible for broad transfer. As the field progresses and more
training studies are conducted using a variety of games, it may be possible to begin to
recognize and isolate certain game aspects associated with broad transfer and specific
cognitive improvements. Other studies might deconstruct action games to explore the
specific components or combination of components associated with perceptual and
cognitive improvements. By following this approach, researchers can move beyond
cataloguing tasks and abilities affected by action video game play; we can begin to
develop a deeper understanding of how experience shapes perception and cognition and
the factors that underlie generalizable skill acquisition. The question we will turn to next
is whether we can understand action gamers better and whether this information can
begin to elucidate the critical components of action video games.
What is an action gamer? What is an action game?

Action Games and Attention 24
In cross sectional studies, Green and Bavelier typically define an action gamer as
having “a minimum of 3–4 days a week of action video-game usage for the previous 6
months”, and action games as ones “that have fast motion, require vigilant monitoring of
the visual periphery, and often require the simultaneous tracking of multiple targets”
(e.g., Green & Bavelier, 2006b, pg. 1466). Boot and colleagues (2008) used similar
definitions, classifying individuals who played video games for seven or more hours a
week over the past two years as action gamers as long as their primary game experience
consisted of fast-paced action games like Halo, Grand Theft Auto and Unreal
Tournament. Thus one challenge of understanding the abilities of action gamers and the
effect of action game experience on perception and cognition is the relatively crude
manner in which these concepts are defined. The definition proposed by Green and
Bavelier would seem to include many different types of games including first-person
shooters, racing games, platform games, and some sports video games. To lump all these
games (and their players) together under the umbrella of “action” obscures potentially
critical information required to understand game effects. The same is true of using
simple and arbitrary cut-offs in terms of number of hours of game play a week over the
past few months/years to identify action video game players. This makes no distinction
between gamers who have been playing for over two decades and gamers who have only
recently developed an interest in action video games. Finally, the term “action gamer” in
general may be a misnomer since in our experience, participants classified as action
gamers often have extensive experience with other game genres.
To better understand the effect of game experience on basic abilities in cross-
sectional studies, it may be fruitful to collect much more extensive data on an

Action Games and Attention 25
individual’s game play history. This history would include video game experience not
just in the recent past, but game experience across the lifetime. Experience with specific
games, how much time a gamer devoted to games at different points in his or her life, and
the age at which a gamer first began playing may all be useful information to begin to
isolate the specific game experiences and game play histories associated with the
strongest game benefits. Similar techniques to collect practice histories of musicians
across their lifetime have proven fruitful in understanding the types of practice activities
most strongly related to exceptional musical skill (Ericsson, Krampe, & Tesch-Römer,
1993).
Can video game improvements transfer beyond simple laboratory tasks?
The large majority of studies have examined the effect of game experience on
simple, process-specific laboratory tests of basic abilities. However, the tasks we
perform every day outside of the laboratory are far more complex, requiring multiple
perceptual and cognitive processes for successful performance. Should we expect video-
game related benefits to transfer to these more complex, and often safety critical tasks
(e.g., driving)? This is critical information needed before video game interventions
should be prescribed to improve everyday performance or to address specific deficits
(e.g., to address the many perceptual and cognitive declines associated with aging and the
impact of these declines on the ability to live independently).
One of the few studies to specifically examine the effects on video game training
on complex task performance was conducted by Gopher, Weil, and Bareket (1994). In
their study, Israeli Air Force cadets were trained for 10 hours on a complex video game
called Space Fortress (see Gopher, Weil, & Siegel, 1989 for game details). Although

Action Games and Attention 26
visually sparse, Space Fortress is a challenging and demanding task which places heavy
demands on attention, memory, and manual control abilities. Surprisingly, compared to a
no-contact control group that received no training, Space Fortress trained cadets
demonstrated measurable improvement in their piloting skills. Furthermore, twice as
many cadets in the no-game group washed out of flight training compared to cadets who
received Space Fortress training. Thus, there is some evidence that game effects may
transfer to complex real-world tasks with important consequences after a relatively short
amount of training in contrast with the limited transfer found in other domains (e.g.,
chess: Chase & Simon, 1973; Gobet & Simon, 1996, computer programming: Pea &
Kurland, 1984; Salomon & Perkins, 1987, cognitive training: Hertzog, Kramer, Wilson,
& Lindenberger, 2009). While this is an encouraging finding, other studies have
observed more limited transfer as a result of Space Fortress training (Boot et al., 2010;
Lee et al., in press).
Another real-world domain that has been investigated with respect to video game
effects is the potential connection between game experience and surgical skill. For
example, Rosenberg, Landsittel, & Averch (2005) found a relationship between video
game experience and laparoscopic surgical skill, but video game training resulted in no
measurable improvement (see also Rosser et al., 2007). While the idea that video game
play can improve surgical skill is intriguing and likely worthy of former exploration, as
discussed previously, there are severe limitations involved in interpreting cross-sectional
and correlational results such as these. Another factor to take into consideration is
training efficiency. That is, what is the benefit of game training compared to benefits
produced by an equivalent amount of training on actual surgical or simulated surgical

Action Games and Attention 27
tasks themselves? At this point, evidence that video game training benefits transfer to
complex, real-world tasks is limited. Evaluating the effects of action video game
experience, not just on basic laboratory tasks, but on meaningful real-world tasks needs
to be a goal of future research, especially before video game training is prescribed to deal
with specific deficits.
Summary and Conclusions
In this chapter, we have reviewed evidence that video game training, especially
action video game training, can result in substantial improvements to visual and
attentional abilities, in addition to a number of other ability changes. Both cross-
sectional data and video game training studies provide supporting evidence that video
game training, unlike other training activities, can result in broad transfer of training. We
consider all of these findings noteworthy and potentially important, but we also discussed
reasons for why these results should be considered tentative. However, we are cautiously
optimistic that more rigorous studies in the future may produce similar results. This
optimism springs from evidence the complex, multi-modal training interventions similar
to the experience provided by modern video games tend to produce the most
generalizable skill (Hertzog, Kramer, Wilson, & Lindenberger, 2009; Lustig, Seidler, &
Reuter-Lorenz, 2009). If this is the case, video game training may be used as a fun and
easy way to address deficits in visual and attentional processing, and many of the
declines associated with cognitive aging. It is our hope that video game training may be
a means to improve not just performance on simple laboratory tasks, but to increase the
efficiency and effectiveness of our interactions with the complex world outside of the
laboratory.

Action Games and Attention 28
References
Ackerman P. L., Kanfer R., & Calderwood C. (2010). Use it or lose it? Wii brain
exercise practice and reading for domain knowledge. Psychology and Aging, 25,
753-766.
Anderson, C. A., & Bushman, B. J. (2001). Effects of violent video games on aggressive
behavior, aggressive cognition, aggressive affect, physiological arousal, and
prosocial behavior: A meta-analytic review of the scientific literature.
Psychological Science, 12, 353-359.
Anderson, A. F., Bavelier, D., & Green, C. S. (2010). Speed-accuracy tradeoffs in
cognitive tasks in action game players. Presented at the 10th Meeting of the
Vision Sciences Society, Sarasota, FL.
Alvarez, G. A., & Franconeri, S. L. (2007). How many objects can you track? Evidence
for a resource-limited tracking mechanism. Journal of Vision, 7(13), 1-10.
Ball, K., Berch, D. B., Helmers, K. F., Jobe, J. B., Leveck, M. D., Marsiske, M., Morris,
J. N., Rebok, G. W., Smith, D. M., Tennstedt, S. L., Unverzagt, F. W., & Willis,
S. L. (2002). Effects of cognitive training interventions with older adults: A
randomized controlled trial. Journal of the American Medical Association, 288,
2271–2281.

Action Games and Attention 29
Ball, K., & Sekuler, R. (1982). A specific and enduring improvement in visual motion
discrimination. Science, 218, 697-698.
Bialystok, E. (2006). Effect of bilingualisim and computer video game experience on the
simon task. Candadian Journal of Experimental Psychology, 60, 68-79.
Boot, W. R., Basak, C., Erickson, K. I., Neider, M., Simons, D. J., Fabiani, M., Gratton,
G., Voss, M. W., Prackash, R., Lee, H., Low, K.A., & Kramer, A. F. (2010).
Transfer of skill engendered by complex task training under conditions of variable
priority. Acta Psychologica, 135, 349-357.
Boot, W. R., Blakely, D. P. & Simons D. J. (2011). Do action video games improve
perception and cognition? Frontiers in Psychology, 2:226.
Boot, W. R., Kramer, A. F., Simons, D. J., Fabiani, M., & Gratton, G. (2008). The effects
of video game playing on attention, memory, and executive control. Acta
Psychologica, 129, 387-398.
Castel, A. D., Pratt, J., & Drummond, E. (2005). The effects of action video game
experience on the time course of inhibition of return and the efficiency of visual
search. Acta Psychologica, 119, 217-230.

Action Games and Attention 30
Catrambone, R., & Holyoak, K. J. (1989). Overcoming contextual limitations on
problem-solving transfer. Journal of Experimental Psychology: Learning,
Memory and Cognition, 15, 1147-1156.
Chase, W. G., & Simon, H. A. (1973). Perception in chess. Cognitive Psychology, 4, 55-
81.
Chisholm, J. D., Hickey, C., Theeuwes, J. & Kingston, A. (2010) Reduced attentional
capture in video game players. Attention, Perception, & Psychophysics, 72, 667-
671.
Clark J. E., Lanphear A. K., & Riddick C. C. (1987). The effects of videogame playing
on the response selection processing of elderly adults. Journal of Gerontology, 42,
82–85.
Clark, K., Fleck, M. S., & Mitroff, S. R. (2011). Enhanced change detection performance
reveals improved strategy use in avid action video game players. Acta
Psychologica, 136, 67-72.
Colzato, L. S., van Leeuwen, P. J. A., van den Wildenberg, W. P. M., & Hommel, B.
(2010). DOOM’d to switch: superior cognitive flexibility in players of first person
shooter games. Frontiers in Psychology, 1, 1-5.

Action Games and Attention 31
Connor, C. E., Egeth, H. E., & Yantis, S. (2004). Visual attention: Bottom-up versus top-
down. Current Biology, 14(19), R850-R852.
DeLisi, R.,&Wolford, J. L. (2002). Improving children’s mental rotation accuracy with
computer game playing. Journal of Genetic Psychology,163, 272-282.
Donohue, S. E., Woldorff, M. G., & Mitroff, S. R. (2010). Video game players show
more precise multisensory temporal processing abilities. Attention, Perception, &
Psychophysics, 72, 1120-1129.
Dye, M.W.G., Green, C. S., Bavelier, D. (2009). Increasing speed of processing with
action video games. Current Directions in Psychological Science, 18(6), 321-326.
Ericsson, K. A., Charness, N., Feltovich, P., & Hoffman, R. R. (Eds.). Cambridge
handbook of expertise and expert performance. Cambridge, UK: Cambridge
University Press.
Ericsson, K. A., Krampe, R. Th., & Tesch-Römer, C. (1993). The role of deliberate
practice in the acquisition of expert performance. Psychological Review, 100(3),
363-406.

Action Games and Attention 32
Ericsson, K. A., & Lehmann, A. C. (1996). Expert and exceptional performance:
Evidence of maximal adaptation to task constraints. Annual Review of Psychology,
47, 273-305.
Ericsson, K. A., & Simon, H. A. (1993). Protocol analysis; Verbal reports as data
(revised edition). Cambridge, MA: Bradford books/MIT Press.
Eriksen, C. W., & St. James, J. D. (1986). Visual attention within and around the field of
focal attention: A zoom lens model. Perception and Psychophysics, 40, 225-240.
Fahle, M., & Morgan, M. (1996). No transfer of perceptual learning between similar
stimuli in the same retinal position. Current Biology, 6, 292-297.
Ferguson. C. J., & Kilburn, J. (2009). The Public health risks of media violence: A meta-
analytic review. Journal of Pediatrics, 154(5), 759-763.
Fiorentini, A., & Berardi, N. (1980). Perceptual learning specific for orientation and
spatial frequency. Nature, 287, 43-44.
Gagnon, D. (1985). Videogames and spatial skills: An exploratory study. Educational
Communication and Technology Journal, 33, 263-275.
Gick, M. L., & Holyoak, K. J. (1980). Analogical problem solving. Cognitive
Psychology, 12, 306-355.

Action Games and Attention 33
Gobet, F., & Simon, H. A. (1996). Recall of rapidly presented random chess positions is a
function of skill. Psychonomic Bulletin & Review, 3(2), 159-163.
Goldstone, R. L. Perceptual Learning. Annual Review of Psychology, 49, 585-612.
Gopher, D., Weil, M., & Bareket, T. (1994). Transfer of skill from a computer game
trainer to flight. Human Factors, 36, 387-405.
Gopher, D., Weil, M., & Siegel, D. (1989). Practice under changing priorities: An
approach to the training of complex skills. Acta Psychologica.Special Issue: The
Learning Strategies Program: An Examination of the Strategies in Skill
Acquisition, 71(1-3), 147-177.
Green, C. S. & Bavelier, D. (2003). Action video game modifies visual selective
attention. Nature, 423, 534-537.
Green, C. S. & Bavelier, D. (2006a). Effect of action video games on the spatial
distribution of visuospatial attention. Journal of Experimental Psychology:
Human Perception and Performance, 1465-1468.
Green, C. S. & Bavelier, D. (2006b). Enumeration versus multiple object tracking: the
case of action video game players. Cognition, 101, 217-245.

Action Games and Attention 34
Green, C. S. & Bavelier, D. (2007). Action video game experience alters the spatial
resolution of attention. Psychological Science, 18, 88-94.
Green, C. S., Pouget, A., & Bavelier, D. (2010). A general mechanism for learning with
action video games: Improved probabilistic inference. Current Biology, 20, 1573-
15792.
Green, C. S., Pouget, A., & Bavelier, D. (2010). Improved probabilistic inference, as a
general learning mechanism with action video games. Current Biology, 20, 1573-
15792.
Greenfield, P. M. & Brannon, C. & Lohr, D.(1994). Two dimensional representation of
movement through three-dimensional space: The role of video game expertise.
Journal of Applied Developmental Psychology, 15, 87-103.
Greenfield P. M., deWinstanley P., Kilpatrick H., Kaye D. (1994). Action video games
and informal education: Effects on strategies for dividing visual attention. Journal
of Applied Developmental Psychology, 15, 105–123.
Hertzog, C., Kramer, A. F., Wilson, R. S., & Lindenberger, U. (2009). Enrichment effects
on adult cognitive development. Psychological Science in the Public Interest, 9,
1–65.

Action Games and Attention 35
Irons, J. L., Remington, R. W. and McLean, J. P. (2011), Not so fast: Rethinking the
effects of action video games on attentional capacity. Australian Journal of
Psychology, 63: no. doi: 10.1111/j.1742-9536.2011.00001.x.
Karle, J. W., Watter, S., & Shedden, J. M. (2010). Task switching in video game players:
Benefits of selective attention but not resistance to proactive interference. Acta
Psychologica, 134, 70-78.
Kramer, A. F., Larish, J. F., & Strayer, D. L. (1995). Training for attentional control in
dual task settings: A comparison of young and old adults. Journal of
Experimental Psychology: Applied, 1, 50-76.
Langer, E., Djikic, M., Pirson, M., Madenci, A., & Donohue, R. (2010). Believing is
seeing: Using mindlessness (mindfully) to improve visual acuity. Psychological
Science, 21, 661-666.
Lee, H., Boot, W. R., Basak, C., Voss, M. W., Prackash, R. S., Neider, M., Erickson, K.
I., Simons, D. J., Fabiani, M., Gratton, G., Low, K. A., Kramer, A. F. (in press).
Performance gains do not transfer to untrained tasks. Acta Psychologica.
Li, R., Polat, U., Makous, W., & Bavelier, D. (2009). Enhancing the contrast sensitivity
function through action video game training. Nature Neuroscience, 12, 549-551.

Action Games and Attention 36
Li, R., Polat, U., Scalzo, F., & Bavelier, D. (2010). Reducing backward masking through
action game training. Journal of Vision, 10(14):33, 1-13.
Lustig, C., Shah, P., Seidler, R., Reuter-Lorenz, P.A. (2009). Aging, training, and the
brain: a review and future directions. Neuropsychological Review, 19, 504-522.
Mack, A., & Rock, I. (1998). Inattentional blindness. Cambridge, MA: MIT Press.
Murphy, K. & Spencer, A. (2009). Playing video games does not make for better visual
attention skills. Journal of Articles in Support of the Null Hypothesis, 6, 1-20.
Nelson, R. A. & Strachan, I. (2009). Action and puzzle video games prime different
speed/accuracy tradeoffs. Perception 38, 1678 – 1687.
Okagaki, L. & Frensch, P.A. (1994). Effects of video game playing on measures of
spatial performance: Gender effects late adolescence. Journal of Applied
Developmental Psychology, 15, 33-58.
Pea, R. D., Kurland, D. M., (1984). On the cognitive effects of learning computer
programming. New Ideas in Psychology, 2, 137-168.
Posner, M. I., Snyder, C. R., & Davidson, B. J. (1980). Attention and the detection of
signals. Journal of Experimental Psychology: General, 109(2), 160-174.

Action Games and Attention 37
Pylyshyn, Z. (1989). The role of location indexes in spatial perception: A sketch of the
FINST spatial index model. Cognition, 32, 65–97.
Rosenberg, B. H., Landsittel, D., & Averch, T. D. (2005). Can video games be used to
predict or improve laparoscopic skills? Journal of Endourology, 19, 372-376.
Rosser, J. C. Jr., Lynch, P. J., Cuddihy, L., Gentile, G. A., Klonsky, J.,& Merrell, R.
(2007). The impact of video games on training surgeons in the 21st century.
Archives of Surgery, 142, 181–186.
Salomon, G. & Perkins, D. N. (1987). Transfer of cognitive skills from programming:
When and how? Journal of Educational Computing Research, 3, 149-169.
Sherry, J. L. (2001). The effects of violent video games on aggression: A meta-analysis.
Human Communications Research, 27(3), 409–431.
Sims, V. K., & Mayer, R. E. (2002). Domain specificity of spatial expertise: The case of
video game players. Applied Cognitive Psychology, 16(1), 97-115.
Shiu, L. P., & Pashler, H. (1992). Improvement in line orientation discrimination is
retinally local but dependent on cognitive set. Perception and Psychophysics, 52,
582-588.

Action Games and Attention 38
Schmidt, R. A., & Bjork, R. A. (1992). New conceptualizations of practice: Common
principles in three paradigms suggest new concepts for training. Psychological
Science, 3(4), 207-217.
Theeuwes, J. (1992). Perceptual selectivity for color and form. Perception &
Psychophysics, 51(6), 599-606.
Theeuwes, J. (1994). Stimulus-driven capture and attentional set: Selective search for
color and visual abrupt onsets. Journal of Experimental Psychology: Human
Perception and Performance, 20(4), 799-806.
Xu. Y., & Chun, M. M. (2009). Selecting and perceiving multiple objects. Trends in
Cognitive Sciences, 13, 167-174.