David Méary

Is perceptual anticipation a motor simulation? A PET study

A large body of psychophysical evidence suggests that perception of human movement is constrained by the observers motor competence. PET measurements of regional cerebral blood flow were performed in eight healthy subjects who were requested, in a forced-choice paradigm, to anticipate the outcome of a single moving dot trajectory depicting the beginning of either mechanical, pointing, or writing movements. Selective activation of the left premotor cortex and of the right intraparietal sulcus was associated with visual anticipation of pointing movements while the left frontal operculum and superior parietal lobule were found to be activated during anticipation of writing movements. These results are discussed in the perspective that the motor system is part of a simulation network, which is used to interpret perceived actions.

The face perception system becomes species-specific at 3 months: An eye-tracking study

The current study aimed at investigating own- vs. other-species preferences in 3-month-old infants. The infants’ eye movements were recorded during a visual preference paradigm to assess whether they show a preference for own-species faces when contrasted with other-species faces. Human and monkey faces, equated for all low-level perceptual characteristics, were used. Our results demonstrated that 3-month-old infants preferred the human face, suggesting that the face perception system becomes species-specific after 3 months of visual experience with a specific class of faces. The eye tracking results are also showing that fixations were more focused on the eye area of human faces, supporting the notion of their importance in holding visual attention.

Preference for human eyes in human infants

Despite evidence supporting an early attraction to human faces, the nature of the face representation in neonates and its development during the first year after birth remain poorly understood. One suggestion is that an early preference for human faces reflects an attraction toward human eyes because human eyes are distinctive compared with other animals. In accord with this proposal, prior empirical studies have demonstrated the importance of the eye region in face processing in adults and infants. However, an attraction for the human eye has never been shown directly in infants. The current study aimed to investigate whether an attraction for human eyes would be present in newborns and older infants. With the use of a preferential looking time paradigm, newborns and 3-, 6-, 9-, and 12-month-olds were simultaneously presented with a pair of nonhuman primate faces (chimpanzees and Barbary macaques) that differed only by the eyes, thereby pairing a face with original nonhuman primate eyes with the same face in which the eyes were replaced by human eyes. Our results revealed that no preference was observed in newborns, but a preference for nonhuman primate faces with human eyes emerged from 3months of age and remained stable thereafter. The findings are discussed in terms of how a preference for human eyes may emerge during the first few months after birth.

Perceptual Factors Affecting the Ability to Assess Facial Resemblance between Parents and Newborns in Humans

People undeniably pay attention to faces, and facial resemblance may act as a kinship cue. However, previous studies have shown that the ability to detect kinship through facial resemblance is limited, and it has been suggested that this may be due to several types of perceptual factors. To further understand the processes that underpin kinship judgment, it is important to investigate which perceptual factors predict the probability of parent–child pairs being detected as related. To this end, we performed two experiments. In the first, we evaluated the ability of human observers to match newborns with one of their parents. In the second, we explored three perceptual factors that may have influenced kinship detection (gender discrimination, facial attractiveness, and perceptual similarity). Results showed that the participants were able to match newborns with one of their parents, even though the task was perceived as difficult. Moreover, our study goes further than previous findings, showing that the perceptual factors investigated may significantly contribute to kinship detection.

An adult face bias in infants that is modulated by face race

The visual preferences of infants for adult versus infant faces were investigated. Caucasian 3.5- and 6-month-olds were presented with Caucasian adult vs. infant face pairs and Asian adult vs. infant face pairs, in both upright and inverted orientations. Both age groups showed a visual preference for upright adult over infant faces when the faces were Caucasian, but not when they were Asian. The preference is unlikely to have arisen because of low-level perceptual features because: (1) no preference was observed for the inverted stimuli, (2) no differences were observed in adult similarity ratings of the upright infant–adult face pairs from the two races, and (3) no differences between the infant and adult faces were observed across races in an image-based analysis of salience. The findings are discussed in terms of the social attributes of faces that are learned from experience and what this implies for developmental accounts of a recognition advantage for adult faces in particular and models of face processing more generally.

Seeing two faces together: preference formation in humans and rhesus macaques

Abstract Humans, great apes and old world monkeys show selective attention to faces depending on conspecificity, familiarity, and social status supporting the view that primates share similar face processing mechanisms. Although many studies have been done on face scanning strategy in monkeys and humans, the mechanisms influencing viewing preference have received little attention. To determine how face categories influence viewing preference in humans and rhesus macaques (Macaca mulatta), we performed two eye-tracking experiments using a visual preference task whereby pairs of faces from different species were presented simultaneously. The results indicated that viewing time was significantly influenced by the pairing of the face categories. Humans showed a strong bias towards an own-race face in an Asian–Caucasian condition. Rhesus macaques directed more attention towards non-human primate faces when they were paired with human faces, regardless of the species. When rhesus faces were paired with faces from Barbary macaques (Macaca sylvanus) or chimpanzees (Pan troglodytes), the novel species’ faces attracted more attention. These results indicate that monkeys’ viewing preferences, as assessed by a visual preference task, are modulated by several factors, species and dominance being the most influential.

The Impact of Early Bilingualism on Face Recognition Processes

Early linguistic experience has an impact on the way we decode audiovisual speech in face-to-face communication. The present study examined whether differences in visual speech decoding could be linked to a broader difference in face processing. To identify a phoneme we have to do an analysis of the speaker’s face to focus on the relevant cues for speech decoding (e.g., locating the mouth with respect to the eyes). Face recognition processes were investigated through two classic effects in face recognition studies: the Other-Race Effect (ORE) and the Inversion Effect. Bilingual and monolingual participants did a face recognition task with Caucasian faces (own race), Chinese faces (other race), and cars that were presented in an Upright or Inverted position. The results revealed that monolinguals exhibited the classic ORE. Bilinguals did not. Overall, bilinguals were slower than monolinguals. These results suggest that bilinguals’ face processing abilities differ from monolinguals’. Early exposure to more than one language may lead to a perceptual organization that goes beyond language processing and could extend to face analysis. We hypothesize that these differences could be due to the fact that bilinguals focus on different parts of the face than monolinguals, making them more efficient in other race face processing but slower. However, more studies using eye-tracking techniques are necessary to confirm this explanation.

Preference for facial averageness: Evidence for a common mechanism in human and macaque infants

Human adults and infants show a preference for average faces, which could stem from a general processing mechanism and may be shared among primates. However, little is known about preference for facial averageness in monkeys. We used a comparative developmental approach and eye-tracking methodology to assess visual attention in human and macaque infants to faces naturally varying in their distance from a prototypical face. In Experiment 1, we examined the preference for faces relatively close to or far from the prototype in 12-month-old human infants with human adult female faces. Infants preferred faces closer to the average than faces farther from it. In Experiment 2, we measured the looking time of 3-month-old rhesus macaques (Macaca mulatta) viewing macaque faces varying in their distance from the prototype. Like human infants, macaque infants looked longer to faces closer to the average. In Experiments 3 and 4, both species were presented with unfamiliar categories of faces (i.e., macaque infants tested with adult macaque faces; human infants and adults tested with infant macaque faces) and showed no prototype preferences, suggesting that the prototypicality effect is experience-dependent. Overall, the findings suggest a common processing mechanism across species, leading to averageness preferences in primates.

Modifications of Visual Field Asymmetries for Face Categorization in Early Deaf Adults: A Study With Chimeric Faces

Right hemisphere lateralization for face processing is well documented in typical populations. At the behavioral level, this right hemisphere bias is often related to a left visual field (LVF) bias. A conventional mean to study this phenomenon consists of using chimeric faces that are composed of the left and right parts of two faces. In this paradigm, participants generally use the left part of the chimeric face, mostly processed through the right optic tract, to determine its identity, gender or age. To assess the impact of early auditory deprivation on face processing abilities, we tested the LVF bias in a group of early deaf participants and hearing controls. In two experiments, deaf and hearing participants performed a gender categorization task with chimeric and normal average faces. Over the two experiments the results confirmed the presence of a LVF bias in participants, which was less frequent in deaf participants. This result suggested modifications of hemispheric lateralization for face processing in deaf participants. In Experiment 2 we also recorded eye movements to examine whether the LVF bias could be related to face scanning behavior. In this second study, participants performed a similar task while we recorded eye movements using an eye tracking system. Using areas of interest analysis we observed that the proportion of fixations on the mouth relatively to the other areas was increased in deaf participants in comparison with the hearing group. This was associated with a decrease of the proportion of fixations on the eyes. In addition these measures were correlated to the LVF bias suggesting a relationship between the LVF bias and the patterns of facial exploration. Taken together, these results suggest that early auditory deprivation results in plasticity phenomenon affecting the perception of static faces through modifications of hemispheric lateralization and of gaze behavior.

Neurogeometry of color vision

In neurogeometry, principles of differential geometry and neuron dynamics are used to model the representation of forms in the primary visual cortex, V1. This approach is well-suited for explaining the perception of illusory contours such as Kanizsas figure (see Petitot (2008) for a review). In its current version, neurogeometry uses achromatic inputs to the visual system as the starting-point for form estimation. Here we ask how neurogeometry operates when the input is chromatic as in color vision. We propose that even when considering only the perception of form, the random nature of the cone mosaic must be taken into account. The main challenge for neurogeometry is to explain how achromatic information could be estimated from the sparse chromatic sampling provided by the cone mosaic. This article also discusses the non-linearity involved in a neural geometry for chromatic processing. We present empirical results on color discrimination to illustrate the geometric complexity for the discrimination contour when the adaptation state of the observer is not conditioned. The underlying non-linear geometry must conciliate both mosaic sampling and regulation of visual information in the visual system.