Hemispheric functional asymmetries and sex effects in visual bistable perception.

This study investigates bistable perception as a function of the presentation side of the ambiguous figures and of participants' sex, to evaluate left-right hemispheric (LH-RH) asymmetries related to consciousness. In two experiments using the divided visual field paradigm, two Rubin's vase-faces figures were projected simultaneously and continuously 180 s long to the left (LVF) and right (RVF; Experiment 1) or to the upper (UVF) and lower (DVF; Experiment 2) visual hemifields of 48 healthy subjects monitored with eye-tracker. Experiment 1 enables stimulus segregation from the LVF to the RH and from the RVF to the LH, whereas Experiment 2 does not. Results from Experiment 1 show that males perceived the face profiles for more time in the LVF than in the RVF, with an opposite trend for the vase, whereas females show a similar pattern of perception in the two hemifields. A related result confirmed the previously reported possibility to have simultaneously two different percepts (qualia) in the two hemifields elicited by the two identic ambiguous stimuli, which was here observed to occur more frequently in males. Similar effects were not observed in Experiment 2. These findings suggest that the percepts display the processing abilities of the hemisphere currently processing the stimulus eliciting them (e.g., RH-faces), and that females and males reflect in bistable perception, a genuine manifestation of consciousness, the well-known hemispheric asymmetry differences they show in ordinary perception.

How head and visual movements affect evaluations of food products.

Many studies suggest that specific movements or postures with shared social meaning can influence mainly verbal stimuli evaluation. On the other hand, several visuospatial biases can interact with this influence. Thus, we tested whether both head and stimuli movements can influence individual attitude towards food pictures. In two experiments, we used images of common foods with a weak positive valence in association with two kinds of movements. In Experiment 1, head movement was induced by presenting food pictures with a vertical or horizontal continuous movement on a computer screen. Conversely, Experiment 2 was conducted to test the effects of participants' own head movements with respect to the same food pictures presented in a fixed position. In neither case did head movements influence product evaluation. However, Experiment 1 revealed that the continuous movement left-right-left in the horizontal condition improved the desire to buy and eat, as well as the willingness to pay for the product shown. Two further experiments, the Experiments 3 and 4 demonstrated, respectively, that this effect disappears if the stimulus does not make the return direction, and that it does not depend on the starting or final placement of the images on the screen. These findings are discussed in the context of embodied cognition and visuospatial bias theories.

Shall I Show My Emotions? The Effects of Facial Expressions in the Ultimatum Game.

Over the past fifteen years, research has demonstrated the central role of interpersonal emotions in communicating intentions, goals and desires. These emotions can be conveyed through facial expressions during specific social interactions, such as in the context of coordination between economic agents, where information inferred from them can influence certain decision-making processes. We investigated whether four facial expressions (happiness, neutral, angry and disgusted) can affect decision-making in the Ultimatum Game (UG). In this economic game, one player (proposer) plays the first move and proposes how to allocate a given amount of money in an anonymous one-shot interaction. If the other player (responder) accepts the proposal, each player receives the allocated amount of money; if he/she rejects the offer, both players receive nothing. During the task, participants acted as the responder (Experiment 1) or the proposer (Experiment 2) while seeing the opponent's facial expression. For the responders, the results show that the decision was mainly driven by the fairness of the offer, with a small main effect of emotion. No interaction effect was found between emotion and offer. For the proposers, the results show that participants modulated their offers on the basis of the responders' expressed emotions. The most generous/fair offers were proposed to happy responders. Less generous/fair offers were proposed to neutral responders. Finally, the least generous/fair offers were proposed to angry and disgusted responders.

The influence of age on the rubber hand illusion.

The rubber hand illusion is a perceptual illusion whereby a model hand is embodied during tactile stimulation. The aim of the present study is to investigate the onset time of the illusion in relation to age. We used two sensors, made using Arduino NANO, in order to record the onset time in which the participants said to start perceiving the illusion. The subjects involved in the experiment were divided in 3 age groups: 16-20, 21-50, and 51-88 years. We observed a clear-cut stronger manifestation of the illusion in the younger group both in terms of proportion of responders vs. non-responders, which was higher in the first age group, and in terms of illusion onset time which was shorter in the same group. These results were substantiated by the responses to a questionnaire measuring subjective perception of the illusion.