Investigating the Features of the M170 in Congenital Prosopagnosia

Face perception generates specific neural activity as early as 170 ms post-stimulus onset, termed the M170 when measured with Magnetoencephalography (MEG). We examined the M170 in six people with congenital prosopagnosia (CP) and 11 typical controls. Previous research indicates that there are two neural generators for the M170 (one within the right lateral occipital area - rLO and one within the right fusiform gyrus - rFG), and in the current study we explored whether these sources reflect the processing of different types of information. Individuals with CP showed face-selective M170 responses within the rLO and right rFG, which did not differ in magnitude to those of the controls. To examine possible links between neural activity and behavior we correlated the CPs' MEG activity generated within rLO and rFG with their face perception skills. The rLO-M170 correlated with holistic/configural face processing, whereas the rFG-M170 correlated with featural processing. Hence, the results of our study demonstrate that individuals with CP can show an M170 that is within the normal range, and that the M170 in the rLO and rFG are involved in different aspects of face processing

New Tests to Measure Individual Differences in Matching and Labelling Facial Expressions of Emotion, and Their Association with Ability to Recognise Vocal Emotions and Facial Identity

Although good tests are available for diagnosing clinical impairments in face expression processing, there is a lack of strong tests for assessing "individual differences"--that is, differences in ability between individuals within the typical, nonclinical, range. Here, we develop two new tests, one for expression perception (an odd-man-out matching task in which participants select which one of three faces displays a different expression) and one additionally requiring explicit identification of the emotion (a labelling task in which participants select one of six verbal labels). We demonstrate validity (careful check of individual items, large inversion effects, independence from nonverbal IQ, convergent validity with a previous labelling task), reliability (Cronbach's alphas of.77 and.76 respectively), and wide individual differences across the typical population. We then demonstrate the usefulness of the tests by addressing theoretical questions regarding the structure of face processing, specifically the extent to which the following processes are common or distinct: (a) perceptual matching and explicit labelling of expression (modest correlation between matching and labelling supported partial independence); (b) judgement of expressions from faces and voices (results argued labelling tasks tap into a multi-modal system, while matching tasks tap distinct perceptual processes); and (c) expression and identity processing (results argued for a common first step of perceptual processing for expression and identity).This research was supported by the Australian Research Council (http://www.arc.gov.au/) grant DP110100850 to RP and EM and the Australian Research Council Centre of Excellence for Cognition and its Disorders (CE110001021) http://www.ccd.edu.au. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Involuntary Facial Expression Processing: Extracting Information from Two Simultaneously Presented Faces

Facial expressions play an important role in successful social interactions, with previous research suggesting that facial expressions may be processed involuntarily. In the current study, we investigate whether involuntary processing of facial expressions would also occur when facial expression distractors are simultaneously presented in the same spatial location as facial expression targets. Targets and distractors from another stimulus class (lions) were also used. Results indicated that angry facial expression distractors interfered more than neutral face distractors with the ability to respond to both face and lion targets. These findings suggest that information from angry facial expressions can be extracted rapidly from a very brief presentation (50 ms), providing compelling evidence that angry facial expressions are processed involuntarily

Dynamic facial expressions are processed holistically, but not more holistically than static facial expressions

There is evidence that facial expressions are perceived holistically and featurally. The composite task is a direct measure of holistic processing (although the absence of a composite effect implies the use of other types of processing). Most composite task studies have used static images, despite the fact that movement is an important aspect of facial expressions and there is some evidence that movement may facilitate recognition. We created static and dynamic composites, in which emotions were reliably identified from each half of the face. The magnitude of the composite effect was similar for static and dynamic expressions identified from the top half (anger, sadness and surprise) but was reduced in dynamic as compared to static expressions identified from the bottom half (fear, disgust and joy). Thus, any advantage in recognising dynamic over static expressions is not likely to stem from enhanced holistic processing, rather motion may emphasise or disambiguate diagnostic featural information

Face matching impairment in developmental prosopagnosia

Developmental prosopagnosia (DP) is commonly referred to as ‘face blindness’, a term that implies a perceptual basis to the condition. However, DP presents as a deficit in face recognition and is diagnosed using memory-based tasks. Here, we test face identification ability in six people with DP, who are severely impaired on face memory tasks, using tasks that do not rely on memory. First, we compared DP to control participants on a standardised test of unfamiliar face matching using facial images taken on the same day and under standardised studio conditions (Glasgow Face Matching Test; GFMT). DP participants did not differ from normative accuracy scores on the GFMT. Second, we tested face matching performance on a test created using images that were sourced from the Internet and so vary substantially due to changes in viewing conditions and in a person’s appearance (Local Heroes Test; LHT). DP participants show significantly poorer matching accuracy on the LHT relative to control participants, for both unfamiliar and familiar face matching. Interestingly, this deficit is specific to ‘match’ trials, suggesting that people with DP may have particular difficulty in matching images of the same person that contain natural day-to-day variations in appearance. We discuss these results in the broader context of individual differences in face matching ability

More than just a problem with faces: Altered body perception in a group of congenital prosopagnosics

It has been estimated that one out of forty people in the general population suffer from congenital prosopagnosia (CP), a neurodevelopmental disorder characterized by difficulty identifying people by their faces. CP involves impairment in recognising faces, although the perception of non-face stimuli may also be impaired. Given that social interaction does not only depend on face processing, but also the processing of bodies, it is of theoretical importance to ascertain whether CP is also characterised by body perception impairments. Here, we tested eleven CPs and eleven matched control participants on the Body Identity Recognition Task (BIRT), a forced-choice match-to-sample task, using stimuli that require processing of body, not clothing, specific features. Results indicated that the group of CPs was as accurate as controls on the BIRT, which is in line with the lack of body perception complaints by CPs. However the CPs were slower than controls, and when accuracy and response times were combined into inverse efficiency scores (IES), the group of CPs were impaired, suggesting that the CPs could be using more effortful cognitive mechanisms to be as accurate as controls. In conclusion, our findings demonstrate CP may not generally be limited to face processing difficulties, but may also extend to body perceptio

Development of face-based trustworthiness impressions in childhood : A systematic review and metaanalysis

Acknowledgements This research was supported by an Australian Government Research Training Program Scholarship to SS. CRediT authorship contribution statement Saba Siddique: Conceptualisation, Data Curation, Formal Analysis, Investigation, Methodology, Writing – Original Draft, Writing – Review and Editing. Clare A.M. Sutherland: Conceptualisation, Methodology, Supervision, Writing – Review and Editing. Romina Palermo: Conceptualisation, Supervision, Writing – Review and Editing. Linda Jeffery: Conceptualisation Supervision, Writing – Review and Editing. Yong Z. Foo: Formal Analysis, Software, Visualisation, Writing – Review and Editing. Derek C. Swe: Investigation, Writing - Review and Editing.Peer reviewedPostprin

Children show neural sensitivity to facial trustworthiness as measured by fast periodic visual stimulation

Acknowledgements We would like to thank Mirha Khan for helping to test pilot participants. Funding This research was supported by an Australian Government Research Training Program Scholarship to SS, and Australian Research Council (ARC) Discovery Early Career Research Award to C.S. [DE190101043], ARC Discovery Project to C.S. and R.P. [DP220101026], and R.P. and L. J. [DP140101743].Peer reviewedPostprin

An objective and reliable electrophysiological marker for implicit trustworthiness perception.

This research was supported by an RTP scholarship from the University of Western Australia to D.S., an Australian Research Council (ARC) Discovery Early Career Research Award to C.S. [DE190101043], the ARC Centre of Excellence in Cognition and its Disorders [CE110001021], ARC Discovery Awards to G.R., C.S. and R.P. [DP170104602] and R.P. [DP140101743] and by ENS Paris-Saclay to S.P.Peer reviewedPublisher PD