Henk Aarts

Publications of Henk Aarts

• Testosterone Affects Gaze Aversion From Angry Faces Outside of Conscious Awareness.

  Authors: David Terburg, Henk Aarts, Jack van Honk

  Psychological science. 04/2012;

  Throughout vertebrate phylogeny, testosterone has motivated animals to obtain and maintain social dominance-a fact suggesting that unconscious primordial brain mechanisms are involved in socialThroughout vertebrate phylogeny, testosterone has motivated animals to obtain and maintain social dominance-a fact suggesting that unconscious primordial brain mechanisms are involved in social dominance. In humans, however, the prevailing view is that the neocortex is in control of primordial drives, and testosterone is thought to promote social dominance via conscious feelings of superiority, indefatigability, strength, and anger. Here we show that testosterone administration in humans prolongs dominant staring into the eyes of threatening faces that are viewed outside of awareness, without affecting consciously experienced feelings. These findings reveal that testosterone motivates social dominance in humans in much the same ways that it does in other vertebrates: involuntarily, automatically, and unconsciously.

• Adaptive Reward Pursuit: How Effort Requirements Affect Unconscious Reward Responses and Conscious Reward Decisions.

  Authors: Erik Bijleveld, Ruud Custers, Henk Aarts

  Journal of experimental psychology. General. 04/2012;

  When in pursuit of rewards, humans weigh the value of potential rewards against the amount of effort that is required to attain them. Although previous research has generally conceptualized thisWhen in pursuit of rewards, humans weigh the value of potential rewards against the amount of effort that is required to attain them. Although previous research has generally conceptualized this process as a deliberate calculation, recent work suggests that rudimentary mechanisms-operating without conscious intervention-play an important role as well. In this article, we propose that humans can perform a basic integration of reward value and effort requirements without conscious awareness. Furthermore, we propose that conscious awareness of rewards allows for the use of more advanced functions in reward pursuit, which consider the specific course of action that leads to reward attainment. Using a monetary reward priming paradigm that allows us to dissect the performance effects of rewards (i.e., coins of different value) into conscious and unconscious components, we tested this proposal in 3 experiments. Overall, results indicate that people rely on a simple yet adaptive mechanism that unconsciously conserves effort during reward pursuit, because it makes people more reward sensitive whenever more effort is required of the body. Moreover, consciousness supports a more sophisticated mode of reward pursuit, via which people can strategically conserve effort even further. We discuss these findings in the context of decision making, motivation, and consciousness. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

• Perceiving an exclusive cause of affect prevents misattribution.

  Authors: Kirsten I Ruys, Henk Aarts, Esther K Papies, Masanori Oikawa, Haruka Oikawa

  Consciousness and cognition. 03/2012;

  Affect misattribution occurs when affective cues color subsequent unrelated evaluations. Research suggests that affect misattribution decreases when one is aware that affective cues are unrelated toAffect misattribution occurs when affective cues color subsequent unrelated evaluations. Research suggests that affect misattribution decreases when one is aware that affective cues are unrelated to the evaluation at hand. We propose that affect misattribution may even occur when one is aware that affective cues are irrelevant, as long as the source of these cues seems ambiguous. When source ambiguity exists, affective cues may freely influence upcoming unrelated evaluations. We examined this using an adapted affect misattribution procedure where pleasant and unpleasant responses served as affective cues that could influence later evaluations of unrelated targets. These affective cues were either perceived as reflecting a single source (i.e., a subliminal affective picture in Experiment 1; one's internal affective state in Experiment 2), or as reflecting two sources (i.e., both) suggesting source ambiguity. Results show that misattribution of affect decreased when participants perceived affective cues as representing one source rather than two.

• Memory and attention for social threat: Anxious hypercoding-avoidance and submissive gaze aversion.

  Authors: David Terburg, Henk Aarts, Jack van Honk

  Emotion (Washington, D.C.). 02/2012;

  Rivalry for dominance is a recurrent challenge in human social interaction. During these social dominance interactions, some people rapidly break eye contact, whereas others merely try to avoid suchRivalry for dominance is a recurrent challenge in human social interaction. During these social dominance interactions, some people rapidly break eye contact, whereas others merely try to avoid such eye-to-eye confrontations. The first is an example of submissive gaze aversion, whereas the second reflects anxious gaze avoidance. We tested these distinct forms of gaze behavior within a social-memory setting and show that anxious individuals vigilantly attend to, superiorly remember, and subsequently avoid social threats (i.e., angry faces). Furthermore, submissive individuals, as indexed by high trait anxiety and low trait anger, exhibit rapid gaze aversion from facial anger. Mechanisms of hypervigilance-avoidance thus seem to underlie natural gaze behavior and enhanced memory for threat in anxiety. Accordingly, we propose the term hypercoding-avoidance, which describes how anxious individuals habitually scan their immediate social environment for threat, remember its location, and subsequently avoid it. Moreover, this is the first experimental evidence showing that submissive gaze aversion is distinct from anxious gaze avoidance. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

• In the eye of the beholder: reduced threat-bias and increased gaze-imitation towards reward in relation to trait anger.

  Authors: David Terburg, Henk Aarts, Peter Putman, Jack van Honk

  PloS one. 01/2012; 7(2):e31373.

  The gaze of a fearful face silently signals a potential threat's location, while the happy-gaze communicates the location of impending reward. Imitating such gaze-shifts is an automatic form ofThe gaze of a fearful face silently signals a potential threat's location, while the happy-gaze communicates the location of impending reward. Imitating such gaze-shifts is an automatic form of social interaction that promotes survival of individual and group. Evidence from gaze-cueing studies suggests that covert allocation of attention to another individual's gaze-direction is facilitated when threat is communicated and further enhanced by trait anxiety. We used novel eye-tracking techniques to assess whether dynamic fearful and happy facial expressions actually facilitate automatic gaze-imitation. We show that this actual gaze-imitation effect is stronger when threat is signaled, but not further enhanced by trait anxiety. Instead, trait anger predicts facilitated gaze-imitation to reward, and to reward compared to threat. These results agree with an increasing body of evidence on trait anger sensitivity to reward.

• Mere exposure to palatable food cues reduces restrained eaters' physical effort to obtain healthy food.

  Authors: Guido M van Koningsbruggen, Wolfgang Stroebe, Henk Aarts

  Appetite. 11/2011; 58(2):593-6.

  We examined whether exposure to cues of attractive food reduces effortful behavior toward healthy foods for restrained eaters. After manipulating food pre-exposure, we recorded handgrip force whileWe examined whether exposure to cues of attractive food reduces effortful behavior toward healthy foods for restrained eaters. After manipulating food pre-exposure, we recorded handgrip force while presenting participants with pictures of healthy food objects. Because participants were led to expect that they could obtain each object (not specified beforehand) by squeezing the handgrip as forcefully as possible while the object was displayed on the screen, the recorded handgrip force constitutes a measure of spontaneous effortful behavior. Results show that restrained eaters, but not unrestrained eaters, displayed less forceful action toward healthy food objects (i.e., lower exertion of force) when pre-exposed to tempting food cues. No effects were found on palatability perceptions of the healthy foods. The results provide further insight into why restrained eaters have difficulties in maintaining a low-calorie diet in food-rich environments.

• When moving without volition: Implied self-causation enhances binding strength between involuntary actions and effects.

  Authors: Myrthel Dogge, Marloes Schaap, Ruud Custers, Daniel M Wegner, Henk Aarts

  Consciousness and cognition. 11/2011; 21(1):501-6.

  The conscious awareness of voluntary action is associated with systematic changes in time perception: The interval between actions and outcomes is experienced as compressed in time. Although thisThe conscious awareness of voluntary action is associated with systematic changes in time perception: The interval between actions and outcomes is experienced as compressed in time. Although this temporal binding is thought to result from voluntary movement and provides a window to the sense of agency, recent studies challenge this idea by demonstrating binding in involuntary movement. We offer a potential account for these findings by proposing that binding between involuntary actions and effects can occur when self-causation is implied. Participants made temporal judgements concerning a key press and a tone, while they learned to consider themselves as the cause of the effect or not. Results showed that implied self-causation (vs. no implied self-causation) increased temporal binding. Since intrinsic motor cues of movement were absent, these results suggest that sensory evidence about the key press caused binding in retrospect and in line with the participant's sense of being an agent.

• Prime and probability: causal knowledge affects inferential and predictive effects on self-agency experiences.

  Authors: Anouk van der Weiden, Henk Aarts, Kirsten I Ruys

  Consciousness and cognition. 09/2011; 20(4):1865-71.

  Experiences of having caused a certain outcome may arise from motor predictions based on action-outcome probabilities and causal inferences based on pre-activated outcome representations. However,Experiences of having caused a certain outcome may arise from motor predictions based on action-outcome probabilities and causal inferences based on pre-activated outcome representations. However, when and how both indicators combine to affect such self-agency experiences is still unclear. Based on previous research on prediction and inference effects on self-agency, we propose that their (combined) contribution crucially depends on whether people have knowledge about the causal relation between actions and outcomes that is relevant to subsequent self-agency experiences. Therefore, we manipulated causal knowledge that was either relevant or irrelevant by varying the probability of co-occurrence (50% or 80%) of specific actions and outcomes. Afterwards, we measured self-agency experiences in an action-outcome task where outcomes were primed or not. Results showed that motor prediction only affected self-agency when relevant actions and outcomes were learned to be causally related. Interestingly, however, inference effects also occurred when no relevant causal knowledge was acquired.

• Positive priming and intentional binding: eye-blink rate predicts reward information effects on the sense of agency.

  Authors: Henk Aarts, Erik Bijleveld, Ruud Custers, Myrthel Dogge, Merel Deelder, Dennis Schutter, Neeltje E M van Haren

  Social neuroscience. 09/2011; 7(1):105-12.

  Human society is strongly rooted in people's experiences of agency; that is, the pervasive feeling that one engages in voluntary behavior and causes one's own actions and resulting outcomes. RewardsHuman society is strongly rooted in people's experiences of agency; that is, the pervasive feeling that one engages in voluntary behavior and causes one's own actions and resulting outcomes. Rewards and positive affect play an important role in the control of voluntary action. However, the role of positive reward signals in the sense of agency is poorly understood. This study examined effects of reward-related information on the sense of agency by employing the intentional binding paradigm. This paradigm measures the extent to which actions and their effects subjectively shift together across time, reflecting a crucial component of people's sense of agency. Results showed that intentional binding is stronger when participants are primed with reward-related information via brief exposure to positive pictures. Interestingly, this positive priming effect was moderated by baseline eye-blink rates (an indirect marker of striatal dopaminergic functioning); reward-related information increased intentional binding mainly for participants displaying higher baseline eye-blink rates. These findings suggest a possible role for striatal dopamine activity in the process by which reward-related information shapes the way people see themselves as agents.

• Unintentional preparation of motor impulses after incidental perception of need-rewarding objects.

  Authors: Harm Veling, Henk Aarts

  Cognition & emotion. 09/2011; 25(6):1131-8.

  Using a new method, we examined whether incidental perception of need-rewarding (positive) objects unintentionally prepares motor action. Participants who varied in their level of need for water wereUsing a new method, we examined whether incidental perception of need-rewarding (positive) objects unintentionally prepares motor action. Participants who varied in their level of need for water were presented with glasses of water (and control objects) that were accompanied by go and no-go cues that required a response (key-press) or withholding a response. Importantly, if need-rewarding objects unintentionally prepare action, presentation of no-go cues should lead to motor inhibition of these prepared motor impulses. Consistent with this hypothesis, results showed that participants relatively high in need for water (and hence, who perceive water as a rewarding, positive object) were slower to react to a successive action probe after withholding a response during perception of water than during perception of the control object, suggesting motor inhibition of unintentionally prepared motor impulses. We propose that incidental perception of need-rewarding objects unintentionally potentiates preparation of motor action to these objects.

• Using stop signals to inhibit chronic dieters' responses toward palatable foods.

  Authors: Harm Veling, Henk Aarts, Esther K Papies

  Behaviour research and therapy. 08/2011; 49(11):771-80.

  Palatable foods in the environment can unintentionally trigger reactions to obtain them, which may interfere with dieting attempts. We tested a strategy to facilitate dieting behavior that makes usePalatable foods in the environment can unintentionally trigger reactions to obtain them, which may interfere with dieting attempts. We tested a strategy to facilitate dieting behavior that makes use of behavioral stop signals that should instantly inhibit chronic dieters' responses toward palatable foods. Participants performed a go/no-go task in which go cues and no-go cues (i.e., the behavioral stop signals) were presented with pictures of palatable foods and control objects. In Study 1, we tested the immediate behavioral effect of presenting stop signals near palatable foods in a reaction time paradigm. In Study 2 we assessed consumption of palatable food that had either consistently been associated with no-go cues, or not. Results show that no-go cues instantly inhibited responses toward palatable foods especially among chronic dieters. Moreover, across a one day period chronic dieters consumed less of a food that had consistently been associated with no-go cues. Stop signals thus appear a promising tool for chronic dieters to control behavior to palatable foods, and we discuss the merits and potential applications of this tool for facilitating dieting behavior.

• When favourites fail: tournament trophies as reward cues in tennis finals.

  Authors: Erik Bijleveld, Ruud Custers, Henk Aarts

  Journal of sports sciences. 08/2011; 29(13):1463-70.

  In tournaments in various sports that feature one-on-one competition, the trophy is sometimes prominently displayed near the athletes during the final. Based on recent research on subtle reward cues,In tournaments in various sports that feature one-on-one competition, the trophy is sometimes prominently displayed near the athletes during the final. Based on recent research on subtle reward cues, we propose that such trophies have the potential to induce choking under pressure in the match favourites, who are known to be most at risk. To test this idea, we analysed real-life tennis performance data (service performance and rally performance) from professional tournaments. While favourites generally outperformed underdogs during rallies, they did not do so in finals in which (a) large amounts of money were at stake and (b) a trophy was on display near the court. These findings support the idea that tournament trophies may distract favourites by continuously reminding them of what is at stake, and via that route may severely thwart their performance.

• I didn't mean to hurt you! Unconscious origins of experienced self-agency over others' emotions.

  Authors: Kirsten I Ruys, Henk Aarts

  Emotion (Washington, D.C.). 06/2011; 12(1):132-41.

  Our conscious experiences of self-agency tell us that we cause and change other people's emotions during social interactions, even without awareness of what we did. How do such experiences of beingOur conscious experiences of self-agency tell us that we cause and change other people's emotions during social interactions, even without awareness of what we did. How do such experiences of being the cause of an outcome, such as the emotions of others, emerge? Previous authorship ascription research suggests that unconsciously primed knowledge about emotions produces a sense of self-agency upon seeing the primed emotions expressed in another agent. Taking into account the crucial role of valence and the nature of one's own actions in understanding others' behaviors, we predicted that preactivated knowledge linked to a particular emotion, in terms of action or valence, increases experienced self-agency upon seeing the emotion in another agent. In four experiments, participants interacted with another agent and observed this agent's neutral expressions change into emotional expressions. Results showed that various kinds of subliminal primes enhance experienced self-agency over the observed emotions. Our findings support the idea that the unconscious authorship ascription process is less rigid when outcomes are socially meaningful. (PsycINFO Database Record (c) 2012 APA, all rights reserved).

• Boosting or choking--how conscious and unconscious reward processing modulate the active maintenance of goal-relevant information.

  Authors: Claire M Zedelius, Harm Veling, Henk Aarts

  Consciousness and cognition. 06/2011; 20(2):355-62.

  Two experiments examined similarities and differences in the effects of consciously and unconsciously perceived rewards on the active maintenance of goal-relevant information. Participants could gainTwo experiments examined similarities and differences in the effects of consciously and unconsciously perceived rewards on the active maintenance of goal-relevant information. Participants could gain high and low monetary rewards for performance on a word span task. The reward value was presented supraliminally (consciously visible) or subliminally at different stages during the task. In Experiment 1, rewards were presented before participants processed the target words. Enhanced performance was found in response to higher rewards, regardless whether they were presented supraliminally or subliminally. In Experiment 2, rewards were presented after participants processed the target words, i.e., during maintenance. Performance increased in response to relatively high rewards when they were presented subliminally, but decreased when they were presented supraliminally. We conclude that both consciously and unconsciously perceived rewards boost resources supporting the maintenance of task-relevant information. Conscious processing of rewards can, however, heavily interfere with an ongoing maintenance process and impair performance.

• Learning of predictive relations between events depends on attention, not on awareness.

  Authors: Ruud Custers, Henk Aarts

  Consciousness and cognition. 06/2011; 20(2):368-78.

  It is generally assumed that storing predictive relations between two events (E(1) consistently precedes E(2)) in memory as bi-directional associations does not require conscious awareness of thisIt is generally assumed that storing predictive relations between two events (E(1) consistently precedes E(2)) in memory as bi-directional associations does not require conscious awareness of this relation, whereas the formation of unidirectional associations that capture the direction of the relation (priming e(1) activates e(2), but e(2) not e(1)) does. This study reports a set of experiments demonstrating that unidirectional associations can be formed even when awareness of the relation is actively prevented, if attention is "tuned" to process predictive relations. When participants engaged in predicting targets based on cues in an unrelated task before the actual acquisition phase, unidirectional associations were formed during this acquisition phase even though E(1) was presented subliminally. This suggests that although processing the relation between events may often be accompanied by awareness of this relation, awareness is not a prerequisite for the formation of unidirectional associations.

• Facing disapproval: performance monitoring in a social context.

  Authors: Maarten A S Boksem, Kirsten I Ruys, Henk Aarts

  Social neuroscience. 03/2011; 6(4):360-8.

  Facial expressions are a potent source of information about how others evaluate our behavior. In the present study, we investigated how the internal performance-monitoring system, as reflected byFacial expressions are a potent source of information about how others evaluate our behavior. In the present study, we investigated how the internal performance-monitoring system, as reflected by error-related negativity (ERN), is affected by external cues of positive (happy faces) or negative evaluation (disgusted faces) of performance. We hypothesized that if the social context indeed impacts on how we evaluate our own performance, we would expect that the same performance error would result in larger ERN amplitudes in the context of negative evaluation than in a positive evaluation context. Our findings confirm our predictions: ERN amplitudes were largest when stimuli consisted of disgusted faces, compared to when stimuli consisted of happy faces. Importantly, ERN amplitudes in our control condition, in which sad faces were used as stimuli, were no different from the positive evaluation condition, ruling out the possibility that effects in the negative evaluation condition resulted from negative affect per se. We suggest that external social cues of approval or disapproval impact on how we evaluate our own performance at a very basic level: The brain processes errors that are associated with social disapproval as more motivationally salient, signaling the need for additional cognitive resources to prevent subsequent failures.

• On the foundations of beliefs in free will: intentional binding and unconscious priming in self-agency.

  Authors: Henk Aarts, Kees van den Bos

  Psychological science. 02/2011; 22(4):532-7.

  The concept of an ability to make choices and to determine one's own outcomes fits well with experiences that most people have, and these experiences form the basis for beliefs in free will. However,The concept of an ability to make choices and to determine one's own outcomes fits well with experiences that most people have, and these experiences form the basis for beliefs in free will. However, the existence of conscious free will is challenged by modern research findings highlighting the unconscious origins of goal-directed behavior that gives rise to free-will beliefs. This report expands on these insights by revealing that both conscious and unconscious processes play an important role in free-will beliefs. Specifically, Experiment 1 demonstrates that free-will beliefs are strengthened when conscious intentions to produce action outcomes bind the perception of action and outcome together in time. Experiment 2 shows that these beliefs are strengthened when unconscious priming of action outcomes creates illusory experiences of self-agency when the primed outcomes occur. Together, these findings suggest that beliefs in free will are associated with self-agency and are enhanced by both conscious and unconscious information processing of goal-directed behavior.

• Paving the path for habit change: cognitive shielding of intentions against habit intrusion.

  Authors: Unna N Danner, Henk Aarts, Esther K Papies, Nanne K de Vries

  British journal of health psychology. 02/2011; 16(Pt 1):189-200.

  The objective of the current study was to examine the cognitive processes that make it possible to use intentions to change one's habitual health-related behaviour. The study used an idiosyncraticThe objective of the current study was to examine the cognitive processes that make it possible to use intentions to change one's habitual health-related behaviour. The study used an idiosyncratic approach to investigate personal existing habits and non-habitual behaviours in a within-participants experiment. Participants first generated habitual and non-habitual behaviours for various daily-life goals (e.g., having lunch, playing sports). Next, they formed intentions to perform non-habitual behaviours in order to attain these goals. Finally, we measured the cognitive accessibility of participants' habitual and non-habitual behaviours with a behaviour recognition task. The findings showed that habitual behaviours were more accessible than the non-habitual behaviours when no intentions were formed (control goals), showing that habits are more readily accessed in mind. However, when participants had formed intentions to use non-habitual behaviours, habitual behaviours for the same goals were inhibited in mind. This could be the cognitive mechanism that shields intentions from habit intrusion and thus enables the pursuit of non-habitual behaviours. The current study demonstrates the role of inhibitory processes in shielding non-habitual intentions in memory. These findings are discussed in the context of success and failure in changing health-related habits.

• Eye tracking unconscious face-to-face confrontations: dominance motives prolong gaze to masked angry faces.

  Authors: David Terburg, Nicole Hooiveld, Henk Aarts, J Leon Kenemans, Jack van Honk

  Psychological science. 02/2011; 22(3):314-9.

  In primates, dominance/submission relationships are generally automatically and nonaggressively established in face-to-face confrontations. Researchers have argued that this process involves anIn primates, dominance/submission relationships are generally automatically and nonaggressively established in face-to-face confrontations. Researchers have argued that this process involves an explicit psychological stress-manipulation mechanism: Striding with a threatening expression, while keeping direct eye contact, outstresses rivals so that they submissively avert their gaze. In contrast, researchers have proposed a reflexive and implicit modulation of face-to-face confrontation in humans, on the basis of evidence that dominant and submissive individuals exhibit vigilant and avoidant responses, respectively, to facial anger in masked emotional Stroop tasks. However, these tasks do not provide an ecologically valid index of gaze behavior. Therefore, we directly measured gaze responses to masked angry, happy, and neutral facial expressions with a saccade-latency paradigm and found that increased dominance traits predict a more prolonged gaze to (or reluctance to avert gaze from) masked anger. Furthermore, greater non-dominance-related reward sensitivity predicts more persistent gaze to masked happiness. These results strongly suggest that implicit and reflexive mechanisms underlie dominant and submissive gaze behavior in face-to-face confrontations.

• Fear signals inhibit impulsive behavior toward rewarding food objects.

  Authors: Harm Veling, Henk Aarts, Wolfgang Stroebe

  Appetite. 02/2011; 56(3):643-8.

  We examined whether presentation of environmental cues that are associated with motor inhibition, i.e., fearful facial expressions, can be effective in controlling unintentionally evoked impulsesWe examined whether presentation of environmental cues that are associated with motor inhibition, i.e., fearful facial expressions, can be effective in controlling unintentionally evoked impulses toward rewarding food objects. Participants were presented with palatable foods or control objects. During presentation of the objects, facial expressions displaying fear, disgust, or neutral emotion were shortly presented. Results show that presentation of fearful facial expressions together with palatable foods slowed down subsequent responding to action probes, but only for participants who perceive palatable foods as highly rewarding and impulse-evoking, i.e., restrained eaters. Facial expressions of disgust did not show this effect. This finding suggests that unintentionally evoked motor impulses toward rewarding objects are inhibited upon presentation of a fear signal. The present research provides new insight on how emotional signals may be used to control impulsive responses toward palatable foods by the environment.