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.

A tentative I/O curve with consciousness: Effects of multiple simultaneous ambiguous figures presentation on perceptual reversals and time estimation.

This study was aimed at investigating mechanisms of consciousness using bistable perception. In 4 experimental conditions, 1, 2, 4 or 8 Rubin's face-vase ambiguous figures were presented for 3 min.In Experiment 1, 40 subjects looked at the center of the screen and pressed a specific key correspondent to the figure where they perceived a reversal. In Experiment 2, 32 subjects controlled with eye-tracker performed a similar task in which they pressed the spacebar whenever they perceived a reversal in any of the figures.At the end of each condition subjects estimated its duration. Results showed that changing the number of figures does not alter the number of reversals, producing a flat I/O curve between the two parameters. Estimated time lapse showed a negative correlation with the number of reversals. These findings are discussed considering the relationships between bistable perception, attention, and consciousness, as well as the time perception literature.

Memory for item-location bindings is enhanced in older adults with appetitive motivationally laden pictures.

Both the selection and consumption of food are biologically necessary for survival. Consequently, individuals may consider food as a primary and biologically relevant stimulus. In addition, recent findings support specific patterns of food preference during the lifespan development. Indeed, the preference for sweet taste largely observed in newborns and children seems to decline in young adults and then re-emerge again in older adults. This motivational preference for sweet food in older adults may be potentially useful in the cognitive domain since many studies have found that motivationally or emotionally laden information is more likely to be detected, stored in memory and retrieved better than neutral information. To address this issue, we designed an item-location binding task with sweet food, savory food and object pictures, and asked young and older adults to maintain information in working memory and respond based on memory for either individual features or feature combination (i.e., identification, location, or combined identification + location information). Results evidenced a significant enhancement of older adults' performance in the binding of motivationally relevant stimuli and their location, evidencing the potential usefulness of motivationally laden stimuli in promoting more effective binding processes and probably, more general working memory processes.

How emotional is a banknote? The affective basis of money perception.

Previous studies have shown that money possesses affective properties even when it is not at stake within a given task. Smaller economic values are generally perceived as less arousing and neutral in valence, whereas larger ones are perceived as more arousing and positive in valence. Moreover, numerical cognitive processes seem to be less prominent than affective ones in the way we perceive economic values. To shed light on the basic affective components of monetary values, we ran three experiments on the perception of banknotes to test (i) whether banknotes with different values (5€ and 100€) trigger different emotional states, (ii) if values are horizontally mapped based on their valence, rather than on their numerical magnitude, and (iii) whether the lateralized sight (in the left or right visual field) of a positive (higher) monetary value interferes with the classification of a negative stimulus. Results showed a coherent pattern that corroborates the idea that money is indeed an affective stimulus, even when it is not at stake within the task. A higher monetary value was shown (i) to have intrinsic rewarding properties that influence the evaluation of a subsequent target, (ii) to be mentally mapped on the right side, which is related to positive approaching of affective stimuli in right-handers, and (iii) to be in conflict with negative-withdrawing targets, but only when the values were presented on the right-positive side of respondents. Results are discussed considering existing theories of the psychological value of money, highlighting the hedonic characteristics of this special affective stimulus.

Affective perception of Euro banknotes: cognitive factors and interindividual differences.

Money can be a tool to achieve a wide range of goals in everyday life. Different studies have reported that both the mere exposure to money and its use as a reward can determine cognitive and social effects. Nevertheless, little is known about the basic affective perception of Euro banknotes. Thus, in the present study we aim to assess differences in valence, arousal and familiarity evaluations of banknote pictures (from 5 to 500€) by taking into account gender, socioeconomic status and Love of Money (LoM) score, which measures the subjective attitude toward money, in a sample of participants. We found that valence and arousal increase with the nominal value of the banknotes, and that the relationship between these affective scores and the nominal value appears to be logarithmic (Weber's law) rather than linear. High value banknotes were evaluated as pleasant, highly arousing, and less familiar. Low value banknotes instead were evaluated as more familiar, less arousing and neutrally valenced. Finally, we found that valence and arousal evaluations are mainly influenced by the LoM score of our participants. Instead, gender and economic condition influenced only arousal scores. These findings suggest the importance of deepening the study of these variables to shed light on money-related biases and abnormal economic behaviors.

Crossmodal congruency effects between sound and food pictures in a forced-choice task.

Research using short musical sequences and musical tracks created by means of computer algorithms has demonstrated that individuals with or without musical skills can match these soundtracks to specific tastes with above-chance accuracy. More recently, a study that investigated implicit effects associated with crossmodal congruency/incongruency between auditory cues and food images found that such soundtracks are effective in eliciting facilitating effects of taste quality classification with congruent food images as well. In the present study, we tested whether this crossmodal congruency between auditory cues and food images may also influence food image choice by means of a forced-choice task. We selected and used sweet and salty soundtracks as stimuli and food images including both low- and high-calorie exemplars and asked participants to select which food they would prefer to eat (one sweet and one salty) while listening to the soundtracks. We found a general greater proportion of food choices in the soundtracks matching tastes conditions, and that soundtracks matching tastes are effective in influencing congruent food image choices, supporting previous research and adding new interesting outcomes.

Independent perceptual reversals for simultaneously presented ambiguous figures.

In two successive experiments using the divided visual field paradigm with vertical or horizontal division, two ambiguous figures, the Rubin's vase-face or the Necker cube, were projected to the right and left or to the upper and lower visual hemifields of 108 healthy volunteers. Stimulation time was 120 s. The main hypotheses were (a) that different percepts of the same ambiguous figure may be simultaneously experienced in the two hemifields and (b) that the type (vertical vs. horizontal) of visual field division influences the reversal frequency and the temporal interdependence of the percepts. Results from the first experiment showed that the temporal interdependence of reversals was very low for both ambiguous figures, suggesting that during part of the stimulation time the subjects could experience different percepts of the same figure (e.g. a vase in the right and face profiles in the left visual hemifields). The second experiment showed that this perceptual dissociation occurred on average during one third of the stimulation time. In both experiments the type of visual field division did not influence either frequency or temporal interdependence of the reversals. When one single ambiguous figure was presented in the centre of the screen, the number of reversals was approximately the sum of the reversals observed with two figures presented simultaneously each in one hemifield.

The effects of music on spatial reasoning.

Studies on the effects of music on spatial reasoning report conflicting results. Some studies show slight effects, and others show no effects but few seem to replicate the strong findings of the first study published in Rauscher et al. Nature, 365(6447), 611-612, (1993). Nonetheless, the debate about the performance enhancing "Mozart effect" remains to be of great interest. In this study, we manipulated different physical parameters of sound traces (amplitude and frequency) to investigate whether particular dimensions may explain the enhancement effects found in spatial tasks following music listening. To this end, we asked 179 undergraduates and 183 older adults to listen to 5-min sound traces (Mozart KV 448, amplitude modulation tone, frequency modulation tone, white noise) and then complete a spatial reasoning task. In particular, results showed that repetitive frequency changes, as occurring in Mozart's melodies or in a frequency modulation tone, enhance performance.

Healthiness or calories? Side biases in food perception and preference.

The visual perception of a product and the ability to categorize it play a central role in food choice. People's opinion of the healthiness and caloric content of a food is influenced substantially by its appearance. Despite that, few studies have analyzed i) which one of the two dimensions of caloric content and healthiness is preferred to categorize food, ii) if these dimensions are mapped on the individuals' horizontal space, and iii) if such biases could influence food preferences. Therefore, through 4 experiments, we investigated which dimension, healthiness or caloric content, is more often used to categorize foods. We also evaluated whether a healthiness/caloric content side bias could be able to influence food preferences. We found that foods were mainly categorized as "Healthy" or "High-calorie" and the latter label was used more often when presented on the right of a foodstuff. Also, foods were categorized as healthier when the "Healthy" label was anchored to the left and the "Unhealthy" one to the right side of a visual analogue scale. Then, we found a more positive evaluation of transformed food when the key assigned to the "Pleasant" choice was on the right compared to the left. Lastly, we found that when presented on the left side, low-calorie was preferred compared to high-calorie food. Our findings shed light on both the fields of food categorization and side biases in food perception and preferences, suggesting the possibility to use these biases to promote a healthy diet and emphasizing the importance of considering this potential confounder in experimental setups.

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.

Modulation of the dichotic right ear advantage during bilateral but not unilateral transcranial random noise stimulation.

Transcranial electrical stimulation (tES) has been increasingly adopted to modulate perceptual and cognitive functions, but the effects on auditory perception are still relatively uncharted. Starting from the evidence that a stronger right ear advantage effect (REA) in dichotic listening positively correlates with speech sound processing, the present study was aimed at modulating the REA by means of high-frequency transcranial Random Noise Stimulation (hf-tRNS). Stimulation was applied over the auditory cortex (AC) either unilaterally (Experiment 1, N = 50) or bilaterally (Experiment 2, N = 24) during a verbal dichotic listening task. The results confirmed the REA both during the sham and the tRNS session in both Experiments. Importantly, a significant enhancement of the REA was found during bilateral hf-tRNS with respect to sham (Experiment 1). No modulation was found when hf-tRNS was applied over the left or right AC with the reference electrode placed on the contralateral shoulder, with respect to sham (Experiment 2). This finding is discussed in the light of previous stimulation studies facing the modulation of hemispheric asymmetries. Our results suggest that the effectiveness of bilateral hf-tRNS in modulating basic speech processing mechanisms could be exploited in the treatment of language impairments.

Emotional faces influence evaluation of natural and transformed food.

Previous evidence showed the presence of a straight relationship between feeding behavior and emotions. Despite that, no studies have focused on the influence of emotional faces on food processing. In our study, participants were presented with 72 couples of visual stimuli composed of a neutral, happy, or disgusted faces (5000 ms duration in Experiment 1, adaptation; 150 ms in Experiment 2, priming) followed by a food stimulus (1500 ms). Food stimuli were grouped in pleasant foods, further divided in natural and transformed, and unpleasant rotten foods. The task consisted in judging the food valence (as 'pleasant' or 'unpleasant') by keypress. Results showed a different pattern of response based on the transformation level of food. In general, the evaluation of natural foods was more rapid compared with transformed foods, maybe for their simplicity and healthier perception. In addition, transformed foods yielded incongruent responses with respect to the preceding emotional face, whereas natural foods yielded congruent responses with respect to it. These effects were independent of the duration of the emotional face (i.e., adaptation or priming paradigm) and may depend on pleasant food stimuli salience.

Author Correction: Emotional faces influence evaluation of natural and transformed food.

This article unfortunately contained two mistakes.

Cortical inhibition of laser pain and laser-evoked potentials by non-nociceptive somatosensory input.

Although the inhibitory action that tactile stimuli can have on pain is well documented, the precise timing of the interaction between the painful and non-painful stimuli in the central nervous system is unclear. The aim of this study was to investigate this issue by measuring the timing of the amplitude modulation of laser evoked potentials (LEPs) due to conditioning non-painful stimuli. LEPs were recorded from 31 scalp electrodes in 10 healthy subjects after painful stimulation of the right arm (C6-C7 dermatomes). Non-painful electrical stimuli were applied by ring electrodes on the second and third finger of the right hand. Electrical stimuli were delivered at +50, +150, +200 and +250 ms interstimulus intervals (ISIs) after the laser pulses. LEPs obtained without any conditioning stimulation were used as a baseline. As compared to the baseline, non-painful electrical stimulation reduced the amplitude of the vertex N2/P2 LEP component and the laser pain rating when electrical stimuli followed the laser pulses only at +150 and +200 ms ISIs. As at these ISIs the collision between the non-painful and painful input is likely to take place at the cortical level, we can conclude that the late processing of painful (thermal) stimuli is partially inhibited by the processing of non-painful (cutaneous) stimuli within the cerebral cortex. Moreover, our results do not provide evidence that non-painful inputs can inhibit pain at a lower level, including the spinal cord.

Both right- and left-handers show a bias to attend others' right arm.

The common-coding hypothesis suggests that the more similar an observed action is to the way the observer would perform it, the stronger is the ensuing activation of motor representations. Therefore, producing actions could prime perception so that observers would be particularly responsive to (i.e. biased to perceive) actions that are related to, and share features with, their own actions. If this similarity principle also applies to handedness, right- and left-handers should be more likely to perceive actions as performed with their dominant rather than non-dominant hand. In two experiments, participants were required to indicate the perceived orientation (front or back view) of pictures of ambiguous human silhouettes performing one-handed manual actions. Experiment 1, in which 300 right-handers and 60 left-handers reported the orientation of a single silhouette seen for as much as they wished, showed that participants perceived the figures more frequently in an orientation congruent with a movement performed with the right rather than the left hand. Experiment 2, in which 12 right-handers and 12 left-handers reported the orientation of 52 silhouettes seen for 300 ms, showed similar results when multiple responses per participant were collected rather than only one. Contrary to our expectations, no difference was observed between right- and left-handers, which might suggest an attentional bias towards the right arm of human bodies in both groups. Moreover, participants were more likely to perceive the figure as front-facing than as back-facing, possibly due to the greater adaptive relevance of approaching compared to receding individuals.

The "consonance effect" and the hemispheres: a study on a split-brain patient.

The association between musical consonance and pleasantness, and between musical dissonance and unpleasantness ("consonance effect") is well established. Furthermore, a number of studies suggest the main involvement of the left hemisphere in the perception of dissonance and that of the right hemisphere in the perception of consonance. In the present study, the consonance effect was studied in a callosotomized patient, D. D. C. and in a control group. In binaural presentations, the patient did not attribute different pleasantness judgements to consonant and dissonant chords, differently from the control group who showed the consonance effect. However, in dichotic presentations (e.g. a chord in one ear and white noise in the other ear), a trend towards the consonance effect was found in D. D. C., but only when chords were presented in his right ear (left hemisphere), whereas the control group confirmed the known hemispheric asymmetry in labelling the pleasantness of consonant and dissonant chords. These results suggest that the right-hemispheric superiority in appreciating consonance might hide the inability of the right hemisphere to classify dissonant chords as unpleasant in the split-brain, whereas the left hemisphere seems capable to differently label the pleasantness of consonant and dissonant chords, even if it is more sensitive to dissonance.

The effects of transcranial random noise stimulation on motor function: A comprehensive review of the literature.

The present review considers all papers published on the topic up to the end of the year 2022. Transcranial random noise stimulation (tRNS) is a non-invasive neuromodulation technique introduced about 15 years ago whose use is becoming increasingly widespread in neuroscience. It consists of the application over the scalp of a weak, white noise-like current, through electrodes having a surface of several square centimetres, for a duration ranging from seconds to minutes. Despite its relatively low spatial and temporal resolution, tRNS has well defined effects on central motor excitability, which critically depend on stimulation parameters. These effects seem to be chiefly based on an effect on neuronal membrane sodium channels and can last much longer than the stimulation itself. While the effects at the cellular level in the motor cortex are becoming progressively clear, much more studies are needed to understand the effects of tRNS on motor behaviour and performance, where initial research results are nevertheless promising, in both basic and applied research.

Auditory Personalization of EMDR Treatment to Relieve Trauma Effects: A Feasibility Study [EMDR+].

According to the WHO (World Health Organization), Eye Movement Desensitization and Reprocessing (EMDR) is an elective therapy to treat people with post-traumatic stress disorders (PTSD). In line with the personalization of therapeutic strategies, through this pilot study, we assessed in people suffering from the effects of trauma the feasibility, safety, acceptance, and efficacy of EMDR enriched with sound stimulation (by administering neutral sounds synchronized with the guided bilateral alternating stimulation of the gaze) and musical reward (musical listening based on the patients' predisposition and personal tastes). Feasibility, quantified by the number of patients who completed the treatment, was excellent as this was the case in 12 out of the 12 enrolled people with psychological trauma. Safety and acceptance, assessed by self-compiled questionnaires, were excellent, with an absence of side effects and high satisfaction. Efficacy, quantified by the number of EMDR treatment sessions required to reach the optimal scores on the Subjective Units of Disturbance (SUD) and Validity of Cognition (VOC) scales typical of EMDR protocols, revealed an average duration of 8.5 (SD 1.2) sessions, which is well below the 12 sessions considered a standard EMDR treatment duration. EMDR+ appears to be a relevant personalization of EMDR, particularly in music-sensitive people, consolidating the therapeutic alliance through a multisensory communicative bond for trauma treatment.

The sound of consciousness: neural underpinnings of auditory perception.

The neural correlates of consciousness (NCC), i.e., patterns of brain activity that specifically accompany a particular conscious experience, have been investigated mainly in the visual system using particularly suited paradigms, such as binocular rivalry and multistable percepts in combination with neural recordings or neuroimaging. Through the same principles, we look here for possible NCC in the auditory modality exploiting the properties of the Deutsch's illusion, a stimulation condition in which a sequence of two specular dichotic stimuli presented in alternation causes an illusory segregation of pitch and side (ear of origin), which can yield up to four different auditory percepts per dichotic stimulus. Using magnetoencephalography in humans, we observed cortical activity specifically accompanying conscious experience of pitch inside an early bilateral network, including the Heschl's gyrus, the middle temporal gyrus, the right inferior, and the superior frontal gyri. The conscious experience of perceived side was instead accompanied by later activity observed bilaterally in the inferior parietal lobe and in the superior frontal gyrus. These results suggest that the NCC are not independent of stimulus features and modality and that, even at the higher cortical levels, the different aspects of a single perceptual scene may not be simultaneously processed.

Neural correlates of cognitive ability.

The challenge to neuroscientists working on intelligence is to discover what neural structures and mechanisms are at the basis of such a complex and variegated capability. Several psychologists agree on the view that behavioral flexibility is a good measure of intelligence, resulting in the appearance of novel solutions that are not part of the animal's normal behavior. This article tries to indicate how the supposed differences in intelligence between species can be related to brain properties and suggests that the best neural indicators may be the ones that convey more information processing capacity to the brain, i.e., high conduction velocity of fibers and small distances between neurons, associated with a high number of neurons and an adequate level of connectivity. The neural bases of human intelligence have been investigated by means of anatomical, neurophysiological, and neuropsychological methods. These investigations have led to two important findings that are briefly discussed: the parietofrontal integration theory of intelligence, which assumes that a distributed network of cortical areas having its main nodes in the frontal and parietal lobes constitutes a probable substrate for smart behavior, and the neural efficiency hypothesis, according to which intelligent people process information more efficiently, showing weaker neural activations in a smaller number of areas than less intelligent people.