Now you see me,now you don't: evidence that chimpanzees understand the role of the eyes in attention

Chimpanzees appear to understand something about the attentional states of others; in the present experiment, we investigated whether they understand that the attentional state of a human is based on eye gaze. In all, 116 adult chimpanzees were offered food by an experimenter who engaged in one of the four experimental manipulations: eyes closed, eyes open, hand over eyes, and hand over mouth. The communicative behavior of the chimpanzees was observed. More visible behaviors were produced when the experimenter's eyes were visible than when the experimenter's eyes were not visible. More vocalizations were produced when the experimenter's eyes were closed than when they were open, but there were no differences in other attention getting behaviors. There was no effect of age or rearing history. The results suggest that chimpanzees use the presence of the eyes as a cue that their visual gestures will be effective.     

Inferring task performance and confidence from displays of eye movements

Eye movements reveal what is at the center of people's attention, which is assumed to coincide with what they are thinking about. Eye-movement displays (visualizations of a person's fixations superimposed onto the stimulus, for example, as dots or circles) might provide useful information for diagnosing that person's performance. However, making inferences about a person's task performance based on eye-movement displays requires substantial interpretation. Using graph-comprehension tasks, we investigated to what extent observers (N = 46) could make accurate inferences about a performer's multiple-choice task performance (i.e., chosen answer), confidence, and competence from displays of that person's eye movements. Observers' accuracy when judging which answer the performer chose was above chance level and was higher for displays reflecting confident performance. Observers were also able to infer performers' confidence from the eye-movement displays; moreover, their own task performance and perceived similarity with the performer affected their judgments of the other's competence.     

Failure of Retrospective Inference in Rats' Taste Aversion

Three experiments explored the possibility of retrospective inference in the rat. Experiment 1 revealed that poisoning of an element of a taste compound after single compound poisoning enhanced aversion to the other element, and that presentation of an element without poison after the compound poisoning reduced aversion to the other element. These results were opposite to those predicted by retrospective inference. Experiment 2 eliminated some confounding variables and examined the effect of element poisoning after compound poisoning. The result again was opposite to what the retrospective view predicts. The results, however, accorded with the idea that within-compound learning was established during compound presentation, and subsequent poisoning or nonpoisoning of one element affected response to the other element via the within-compound learning. In Experiment 3, the possibility of within-compound learning was reduced by using sequential presentation of tastes, but there was no indication of retrospective inference even under this condition.     

Mentalizing eye contact with a face on a video: Gaze direction does not influence autonomic arousal

Recent research has revealed enhanced autonomic and subjective responses to eye contact only when perceiving another live person. However, these enhanced responses to eye contact are abolished if the viewer believes that the other person is not able to look back at the viewer. We purported to investigate whether this “genuine” eye contact effect can be reproduced with pre‐recorded videos of stimulus persons. Autonomic responses, gaze behavior, and subjective self‐assessments were measured while participants viewed pre‐recorded video persons with direct or averted gaze, imagined that the video person was real, and mentalized that the person could see them or not. Pre‐recorded videos did not evoke similar physiological or subjective eye contact effect as previously observed with live persons, not even when the participants were mentalizing being seen by the person. Gaze tracking results showed, however, increased attention allocation to faces with direct gaze compared to averted gaze directions. The results suggest that elicitation of the physiological arousal in response to genuine eye contact seems to require spontaneous experience of seeing and of being seen by another individual.     

Factors contributing to individual differences in facial expression categorisation

Individuals vary in perceptual accuracy when categorising facial expressions, yet it is unclear how these individual differences in non-clinical population are related to cognitive processing stages at facial information acquisition and interpretation. We tested 104 healthy adults in a facial expression categorisation task, and correlated their categorisation accuracy with face-viewing gaze allocation and personal traits assessed with Autism Quotient, anxiety inventory and Self-Monitoring Scale. The gaze allocation had limited but emotion-specific impact on categorising expressions. Specifically, longer gaze at the eyes and nose regions were coupled with more accurate categorisation of disgust and sad expressions, respectively. Regarding trait measurements, higher autistic score was coupled with better recognition of sad but worse recognition of anger expressions, and contributed to categorisation bias towards sad expressions; whereas higher anxiety level was associated with greater categorisation accuracy across all expressions and with increased tendency of gazing at the nose region. It seems that both anxiety and autistic-like traits were associated with individual variation in expression categorisation, but this association is not necessarily mediated by variation in gaze allocation at expression-specific local facial regions. The results suggest that both facial information acquisition and interpretation capabilities contribute to individual differences in expression categorisation within non-clinical populations.     

Colour specificity in episodic and in perceptual object recognition with enhanced colour impact

In three experiments we investigated the perceptual specificity of explicit (old-new object recognition) and implicit memory (word-picture matching) for colour. In order to enhance the impact of colour on processing, we increased the number of colours per object and we impaired shape information. We presented multicoloured pictures (Experiment 1), blurred and partially occluded pictures (Experiment 2) and coloured line drawings in visual noise (Experiment 3). Experiments 1 and 2 had an intentional study phase; the study phase of Experiment 3 was an incidental colour or category naming task. Changing colour from study to test always had negative effects on episodic recognition although colour was irrelevant. In contrast, in the matching task old pictures were generally matched faster than new ones independent of their colour congruence. In Experiment 3, an additional small advantage of congruent colours and of semantic processing occurred. We conclude that two different memory representations contribute to these tasks. Changes of an achromatic, more abstract representation, that is used in normal object recognition, and a representation of the specific exemplar that includes colour. This latter token is used in episodic recognition as well as in unusual perceptual tasks (Experiment 3).     

Risk aversion in information seeking

The information gain model argues that participants select alternatives with a larger expected value of information gain. The present study investigated risk aversion in information seeking to examine whether the expected value always determines information-seeking behaviour. For this investigation, we used a scale method selection task in which participants were required to select one of two scales for weighing coins in order to find an underweight coin. Two experiments showed that participants more frequently selected the alternative that provided information gain without risk, although its expected information gain was smaller. This finding indicates the presence of risk aversion in information seeking, suggesting that information-seeking behaviour is affected by risk associated with obtaining information gain.     

Conditioned ethanol aversion in rats induced by voluntary wheel running,forced swimming,and electric shock: An implication for aversion therapy of alcoholism

This study was planned to demonstrate rats’ acquisition of aversion to ethanol solution consumed before voluntary running, forced swimming, or electric shock delivery. Wistar rats under water deprivation were allotted to four groups of eight rats each, and all rats were allowed to drink 5% ethanol solution for 15 min. Immediately after the ethanol drinking, rats of Group Run were put into the individual running wheels for 15 min, those of Group Swim were put into the individual swimming pools for 15 min, those of Group Shock received electric shocks for 15 min (15 0.45-mA shocks of 0.7s with the intershock interval of 1 min) in the individual small chambers, and those of Group Control were directly returned back to the home cages. This procedure was repeated for six days, followed by a two-day choice test of ethanol aversion where a bottle containing 5% ethanol solution and a bottle of tap water were simultaneously presented for 15 min. In the test, Groups Run, Swim, and Shock drank ethanol solution significantly less than tap water, while Group Control drank both fluids equally. The effects of running, swimming, and shock were equivalent. The successful demonstration of acquired ethanol aversion induced by exercise (running and swimming) or shock in rats suggests an avenue for clinical application of exercise and shock treatments for human alcoholics, though there are many issues to be resolved before the practical use.     

Possible olfaction-based mechanisms in human kin recognition and inbreeding avoidance

Three studies explored kin recognition through olfaction. In Study I, adults (N=22) were tested for ability to identify the odors of themselves; their mother; their father; a sister; a brother; a familiar, unrelated individual; and a stranger. Acquaintances were identified as accurately as biological kin, implicating an association mechanism. However, biological kin were often confused, implicating phenotypic matching. Same-sex kin were confused more than opposite-sex kin, but mainly when same-sex kin had odors of similar intensity. Study II implicated phenotypic matching. Mothers (N=18) could identify their biological children but not their stepchildren. The preadolescent children (N=37) identified their full siblings but not half-siblings or stepsiblings. Thus, olfactory cues may help mediate favoritism of blood relatives. In Study III, mutual olfactory aversion occurred only in the father-daughter and brother-sister nuclear family relationships. Recognition occurred between opposite-sex siblings but not same-sex siblings. Thus, olfaction may help mediate the development of incest avoidance during childhood (the Westermarck effect).