Detecting and identifying response-compatible stimuli

Previous work indicates that action-control processes influence perceptual processes: The identification probability of a left- or right-pointing arrow is reduced when it appears during the execution of a compatible left-right-key press (Müsseler & Hommel, in press). The present study addresses the question of whether this effect would also be observed in a detection task—that is, with judgments that do not require discriminating between left- and right-pointing arrows. Indeed, we found comparable effects in both the identification task and the detection task. This outcome is interpreted within a commoncoding framework, which holds that stimulus processing and action control operate on the same codes.     

Detecting and identifying change: additions versus deletions

The recognition of changes in the features of objects was examined as a function of the nature of the change (additions, deletions, no change). In two experiments we assessed both detection (noticing whether the stimulus had changed) and identification (specifying the exact nature of the change). Both detection and identification were expected to depend upon the subject's awareness of the subsequent recognition tasks while the original stimuli were encoded. In Experiment 1, subjects were not aware of subsequent detection and identification tasks while they initially viewed study slides of the to-be-changed stimuli. During the subsequent presentation of the test stimuli, detection and identification were superior for additions. On the other hand, in Experiment 2 when subjects were aware of the subsequent recognition tasks while viewing each study slide, a detection advantage for deletions obtained. Identification performance depended upon a further factor, whether the features of a stimulus were codable. Only in codable stimuli were deletions easier to identify than additions. The differences between the two experiments in detecting and identifying additions versus deletions are consistent with Tversky's (1977) research that stresses the importance of specifying which representation (the study stimulus or the test stimulus) is the subject of comparison in the comparative judgment.     

Detecting symmetry and faces: Separating the tasks and identifying their interactions

Face and symmetry processing have common characteristics, and several lines of evidence suggest they interact. To characterize their relationship and possible interactions, in the present study we created a novel library of images in which symmetry and face-likeness were manipulated independently. Participants identified the target that was most symmetric among distractors of equal face-likeness (Experiment 1) and identified the target that was most face-like among distractors of equal symmetry (Experiment 2). In Experiment 1, we found that symmetry judgments improved when the stimuli were more face-like. In Experiment 2, we found a more complex interaction: Image symmetry had no effect on detecting frontally viewed faces, but worsened performance for nonfrontally viewed faces. There was no difference in performance for upright versus inverted images, suggesting that these interactions occurred on the parts-based level. In sum, when symmetry and face-likeness are independently manipulated, we find that each influences the perception of the other, but the nature of the interactions differs.     

Mutual gaze and social cognition

I examine the role of mutual gaze in social cognition. I start by discussing recent studies of joint visual attention in order to show that social cognition is operative in infancy prior to the emergence of theoretical skills required to make judgments about other people's states of mind. Such social cognition depends on the communicative potential inherent in human bodies. I proceed to examine this embodied social cognition in the context of Merleau-Ponty's views on vision. I expose some inner difficulties within Merleau-Ponty's position as well as to point out the ways of resolving them by means of combined insights from developmental psychology and the analyses of self-other relations from philosophies of dialogue.     

The malleability of age-related positive gaze preferences: training to change gaze and mood

Older adults show positive gaze preferences, but to what extent are these preferences malleable? Examining the plasticity of age-related gaze preferences may provide a window into their origins. We therefore designed an attentional training procedure to assess the degree to which we could shift gaze and gaze-related mood in both younger and older adults. Participants completed either a positive or negative dot-probe training. Before and after the attentional training, we obtained measures of fixations to negatively valenced images along with concurrent mood ratings. We found differential malleability of gaze and mood by age: for young adults, negative training resulted in fewer posttraining fixations to the most negative areas of the images, whereas positive training appeared more successful in changing older adults' fixation patterns. Young adults did not differ in their moods as a function of training, whereas older adults in the train negative group had the worst moods after training. Implications for the etiology of age-related positive gaze preferences are considered.     

Stimulus exposure and gaze bias: A further test of the gaze cascade model

We tested predictions derived from the gaze cascade model of preference decision making (Shimojo, Simion, Shimojo, & Scheier, 2003; Simion & Shimojo, 2006, 2007). In each trial, participants’ eye movements were monitored while they performed an eight-alternative decision task in which four of the items in the array were preexposed prior to the trial. Replicating previous findings, we found a gaze bias toward the chosen item prior to the response. However, contrary to the prediction of the gaze cascade model, preexposure of stimuli decreased, rather than increased, the magnitude of the gaze bias in preference decisions. Furthermore, unlike the prediction of the model, preexposure did not affect the likelihood of an item being chosen, and the pattern of looking behavior in preference decisions and on a nonpreference control task was remarkably similar. Implications of the present findings in multistage models of decision making are discussed.     

The effect of gaze on gaze direction while looking at art

In highly controlled cuing experiments, conspecific gaze direction has powerful effects on an observer’s attention. We explored the generality of this effect by using paintings in which the gaze direction of a key character had been carefully manipulated. Our observers looked at these paintings in one of three instructional states (neutral, social, or spatial) while we monitored their eye movements. Overt orienting was much less influenced by the critical gaze direction than what the cuing literature might suggest: An analysis of the direction of saccades following the first fixation of the critical gaze showed that observers were weakly biased to orient in the direction of the gaze. Over longer periods of viewing, however, this effect disappeared for all but the social condition. This restriction of gaze as an attentional cue to a social context is consistent with the idea that the evolution of gaze direction detection is rooted in social communication. The picture stimuli from this experiment can be downloaded from the Psychonomic Society’s Archive of Norms, Stimuli, and Data, www.psychonomic.org/archive.     

Subliminal gaze cues increase preference levels for items in the gaze direction

Another individual’s gaze automatically shifts an observer’s attention to a location. This reflexive response occurs even when the gaze is presented subliminally over a short period. Another’s gaze also increases the preference level for items in the gaze direction; however, it was previously unclear if this effect occurs when the gaze is presented subliminally. This study showed that the preference levels for nonsense figures looked at by a subliminal gaze were significantly greater than those for items that were subliminally looked away from (Task 1). Targets that were looked at by a subliminal gaze were detected faster (Task 2); however, the participants were unable to detect the gaze direction (Task 3). These results indicate that another individual’s gaze automatically increases the preference levels for items in the gaze direction without conscious awareness.     

Visual onset and offset latencies

An experiment was designed to test the hypothesis that the latency of response to the offset of light can sometimes be shorter than the latency of response to the onset. The subjects' task involved the temporal order discrimination of the offset of one light and the onset of another. The results indicated that offsets were perceived about 40 ms earlier than onsets. Reasons were suggested for the shorter onset latencies found by other investigators, and a model was proposed to account for changes in the relative latencies of onsets and offsets as a function of stimulus duration and intensity.     

Spatial interference between gaze direction and gaze location: A study on the eye contact effect

Perceived gaze in faces is an important social cue that influences spatial orienting of attention. In three experiments, we examined whether the social relevance of gaze direction modulated spatial interference in response selection, using three different stimuli: faces, isolated eyes, and symbolic eyes (Experiments 1, 2, and 3, respectively). Each experiment employed a variant of the spatial Stroop paradigm in which face location and gaze direction were put into conflict. Results showed a reverse congruency effect between face location to the right or left of fixation and gaze direction only for stimuli with a social meaning to participants (Experiments 1 and 2). The opposite was observed for the nonsocial stimuli used in Experiment 3. Results are explained as facilitation in response to eye contact.     

Spatial interference between gaze direction and gaze location: a study on the eye contact effect

Perceived gaze in faces is an important social cue that influences spatial orienting of attention. In three experiments, we examined whether the social relevance of gaze direction modulated spatial interference in response selection, using three different stimuli: faces, isolated eyes, and symbolic eyes (Experiments 1, 2, and 3, respectively). Each experiment employed a variant of the spatial Stroop paradigm in which face location and gaze direction were put into conflict. Results showed a reverse congruency effect between face location to the right or left of fixation and gaze direction only for stimuli with a social meaning to participants (Experiments 1 and 2). The opposite was observed for the nonsocial stimuli used in Experiment 3. Results are explained as facilitation in response to eye contact.     

Age effects and gaze patterns in recognising emotional expressions: An in-depth look at gaze measures and covariates

The present study investigated predictors of age effects in emotion recognition accuracy. Older and younger adults were tested on a battery of cognitive, vision, and affective questionnaires; participants' eyes were also tracked while they completed an emotion recognition task. Older adults were worse at recognising sad, angry, and fearful expressions than younger adults. When controlling for covariates related to emotion recognition accuracy, younger adults still outperformed older adults in recognising anger and sadness. Younger adults tended to pay more attention to the eyes than older adults. Results suggest that age-related gaze patterns in emotion recognition may depend on the specific emotion being recognised and may not generalise across stimuli sets.     

Trade-offs between gaze and working memory use

Eye movements during natural tasks suggest that observers do not use working memory to capacity but instead use eye movements to acquire relevant information immediately before needed. Results here however, show that this strategy is sensitive to memory load and to observers' expectations about what information will be relevant. Depending upon the predictability of what object features would be needed in a brick sorting task, subjects spontaneously modulated the order in which they sampled and stored visual information using working memory more when the task was predictable and reverting to a just-in-time strategy when the task was unpredictable and the memory load was higher. This self organization was evidenced by subjects' sequence of eye movements and also their sorting decisions following missed feature changes. These results reveal that attentional selection, fixations, and use of working memory reflect a dynamic optimization with respect to a set of constraints, such as task predictablity and memory load. They also reveal that change blindness depends critically on the local task context, by virtue of its influence on the information selected for storage in working memory.     

Gaze following and gaze priming in lemurs

Although primates have often been found to co-orient visually with other individuals, members of these same species have usually failed to use co-orientation to find hidden food in object-choice experiments. This presents an evolutionary puzzle: what is the function of co-orientation if it is not used for a function as basic as locating resources? Co-orientation responses have not been systematically investigated in object-choice experiments, and requiring co-orientation with humans (as is typical in object-choice tasks) may underestimate other species’ abilities. Using an object-choice task with conspecific models depicted in photographs, we provide experimental evidence that two lemur species (Eulemur fulvus, n = 4, and Eulemur macaco, n = 2) co-orient with conspecifics. Secondly, by analysing together two measures that have traditionally been examined separately, we show that lemurs’ gaze following behaviour and ultimate choice are closely linked. Individuals were more likely to choose correctly after having looked in the same direction as the model, and thus chose objects correctly more often than chance. We propose a candidate system for the evolutionary origins of more complex gaze following: ‘gaze priming.’     

Orienting to eye gaze and face processing

The author conducted 7 experiments to examine possible interactions between orienting to eye gaze and specific forms of face processing. Participants classified a letter following either an upright or inverted face with averted, uninformative eye gaze. Eye gaze orienting effects were recorded for upright and inverted faces, irrespective of whether the faces were simple, schematic faces or more realistic faces. In contrast, inversion affected orienting to targets appearing along the vertical axis. Switching the contrast between the iris and sclera reversed orienting to eye gaze. Lifting the eyelid to expose more of the iris-sclera contrast led to a potentiation of orienting to eye gaze. Raising the eyebrow alone without the eyelid did not affect orienting. The findings suggest that local perceptual information is critical for orienting to eye gaze and that the effect can occur with a degree of independence from certain types of face processing.     

Orienting to counterpredictive gaze and arrow cues

In separate experiments, counterpredictive arrow, eye gaze, or abrupt-onset cues were used to test the hypothesis that individual differences in voluntary control influence involuntary orienting. In contrast with previous findings (Friesen, Ristic, & Kingstone, 2004), involuntary orienting effects were found for arrow cues.Furthermore, for both eye gaze and arrow cues, individual differences in voluntarycontrol were associatedwith involuntary orienting: Involuntary orienting effects were larger for participants who were more effective at using the cue to reorient attention, and also for participants who reported greater ability to control attention. Orienting to abrupt-onset cues was not correlated to individual differences in self-reported attentional control. The findings show that eye gaze and arrow cues instigate similar involuntary and voluntary effects and that involuntary orienting to symbolic cues is linked to individual differences in voluntary control.     

Fixation instruction influences gaze cueing

Studies have shown that perceiving another person's gaze shift facilitates responses in the direction of the perceived gaze shift. While it is often assumed that participants in these experiments remain fixated on the cue in the cueing interval, eye gaze is not always recorded to confirm this. The data presented here suggest that the effect of gaze cues on responses to peripheral targets depends on whether participants make eye movements prior to the onset of the target. Participants who were required to fixate showed cueing effects at short cue-target intervals, but no cueing at later intervals. Participants who could look around, often chose to do so, and showed the same positive cueing effects at the shorter interval, but negative cueing effects (suggestive of inhibition of return) at the longer interval.