Jennifer Yoon

Differential Development of the Ventral Visual Cortex Extends Through Adolescence

The ventral temporal cortex (VTC) in humans includes functionally defined regions that preferentially respond to objects, faces, and places. Recent developmental studies suggest that the face selective region in the fusiform gyrus (‘fusiform face area’, FFA) undergoes a prolonged development involving substantial increases in its volume after 7 years of age. However, the endpoint of this development is not known. Here we used functional magnetic resonance imaging (fMRI) to examine the development of face-, object- and place selective regions in the VTC of adolescents (12–16 year olds) and adults (18–40 year olds). We found that the volume of face selective activations in the right fusiform gyrus was substantially larger in adults than in adolescents, and was positively correlated with age. This development was associated with higher response amplitudes and selectivity for faces in face selective regions of VTC and increased differentiation of the distributed response patterns to faces versus non-face stimuli across the entire VTC. Furthermore, right FFA size was positively correlated with face recognition memory performance, but not with recognition memory of objects or places. In contrast, the volume of object- and place selective cortical regions or their response amplitudes did not change across these age groups. Thus, we found a striking and prolonged development of face selectivity across the VTC during adolescence that was specifically associated with proficiency in face recognition memory. These findings have important implications for theories of development and functional specialization in VTC.

Functionally Defined White Matter Reveals Segregated Pathways in Human Ventral Temporal Cortex Associated with Category-Specific Processing

It is unknown if the white-matter properties associated with specific visual networks selectively affect category-specific processing. In a novel protocol we combined measurements of white-matter structure, functional selectivity, and behavior in the same subjects. We find two parallel white-matter pathways along the ventral temporal lobe connecting to either face-selective or place-selective regions. Diffusion properties of portions of these tracts adjacent to face- and place-selective regions of ventral temporal cortex correlate with behavioral performance for face or place processing, respectively. Strikingly, adults with developmental prosopagnosia (face blindness) express an atypical structure-behavior relationship near face-selective cortex, suggesting that white-matter atypicalities in this region may have behavioral consequences. These data suggest that examining the interplay between cortical function, anatomical connectivity, and visual behavior is integral to understanding functional networks and their role in producing visual abilities and deficits.

Contagious yawning: a reflection of empathy, mimicry, or contagion?

Yawning is a curious behavioural phenomenon that at times may be described as ‘contagious’, appearing to spread from one individual to another. Contagious yawning is seen in several primate species, including humans (Provine 1986; Baenninger 1997; Campbell et al. 2009; Palagi et al. 2009). Here we argue that contagious yawning, particularly the newly documented phenomenon of cross-species contagious yawning (JolyMascheroni et al. 2008), is an important avenue of research. In the discussion that follows, we hope to encourage further experimentation to identify the possible functions of and mechanisms underlying contagious yawning. Yawning has several convenient properties that make it ideal for cross-species research. First, it is already in the behavioural repertoire of a broad spectrum of vertebrates, from fish to birds to mammals (Baenninger 1997; Gallup et al. 2009). Thus, cross-species comparisons do not hinge on complex and error-prone training protocols. Because it occurs spontaneously at low frequency, crossindividual yawning in a temporally correlated but asynchronous way is easy to detect and difficult to explain as chance. Our principal interest in cross-species contagious yawning is its potential link with social cognitive capacities. As described in a recent report by Joly-Mascheroni et al. (2008), 21 of 29 pet dogs, Canis familiaris, tested yawned after seeing human yawns while none yawned after seeing silent mouth openings. A prominently raised hypothesis in Joly-Mascheroni et al. (2008, page 447) is that ‘contagious yawning of dogs may relate to their capacity for empathy’. This intriguing hypothesis is also proposed in findings of contagious yawning in nonhuman primates (Palagi et al. 2009) and as explaining the relative lack of contagious yawning in autistic children (Senju et al. 2007). Empathy is notoriously difficult to define (Preston & de Waal 2002). While empathy is not defined in Joly-Mascheroni et al. or Palagi et al., and can be construed in many ways, a related letter (Senju et al. 2007) cites two references that both offer high-level definitions for the term. One refers to empathy as ‘the capacity to predict and to respond to the behavior of agents (.) by inferring their mental states’ (Baron-Cohen et al. 2005, page 819), and the other refers to contagious yawning as ‘a consequence of a theory of * Correspondence: J. M. D. Yoon, Department of Psychology, Stanford University, Stanford, CA 94305, U.S.A. E-mail address: jennifer.yoon@stanford.edu (J.M.D. Yoon). 1 Equal contributions. 2 C. Tennie is at the Department of Developmental and Comparative Psychology, Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, D-04103 Leipzig, Germany.

Brief Report: Broader Autism Phenotype Predicts Spontaneous Reciprocity of Direct Gaze.

We report evidence for a relationship in the general population between self-reported autism-associated traits and the spontaneous reciprocation of direct gaze, a behavior that we propose may reflect a tendency to synchronize with social partners. Adults viewed videos of actors whose gaze was either directed towards or averted from them. Individuals with lower scores on four subscales of the Autism-Spectrum Quotient (AQ) scale showed a greater tendency to look at directed relative to averted eyes; individuals with higher scores on the AQ did not. This relationship was specific to autism-associated traits and to gaze towards the eyes; it did not generalize to a social anxiety measure or to gaze towards the mouth. We discuss implications for our understanding of the broader autism phenotype.

Striking deficiency in top-down perceptual reorganization of two-tone images in preschool children

Two-tone images (black and white transformations of gray-scale photographs) can be difficult for adult observers to recognize. However, following a brief presentation of the original photograph from which the two-tone image was created, adults experience rapid and long-lasting perceptual reorganization, such that after the initial presentation, the two-tone image becomes immediately and easily recognizable. Following a previously reported observation [1], we present evidence that, in contrast to the effortless recognition seen in adults, preschool-aged children are generally unable to recognize two-tone images even when the photograph is simultaneously available. When asked to draw corresponding parts of the photo and two-tone images, children often marked correct regions of the photo and nonsensical regions of the two-tone image. A control experiment showed that children are fully able to mark corresponding parts of two identical photographs. These results point to a dramatic lack of cue-driven perceptual reorganization in young children under conditions that trigger instant recognition in adults. We suggest that this robust phenomenon may provide a window into the development of top-down mechanisms of perceptual learning and consider interventions (e.g., |2-4]) that may improve young childrens ability to use one image to reorganize another.

When and how does autism begin

Jones and Klin recently found that the well-known decreased fixations to eyes in children with autism spectrum disorder (ASD) are not present throughout infancy; instead a decline in eye fixations between 2 and 6 months predicts diagnosis. This decline is the earliest behavioral pattern linked to autism to date.

Cultural differences in perceptual reorganization in US and Pirahã adults.

Visual illusions and other perceptual phenomena can be used as tools to uncover the otherwise hidden constructive processes that give rise to perception. Although many perceptual processes are assumed to be universal, variable susceptibility to certain illusions and perceptual effects across populations suggests a role for factors that vary culturally. One striking phenomenon is seen with two-tone images—photos reduced to two tones: black and white. Deficient recognition is observed in young children under conditions that trigger automatic recognition in adults. Here we show a similar lack of cue-triggered perceptual reorganization in the Pirahã, a hunter-gatherer tribe with limited exposure to modern visual media, suggesting such recognition is experience- and culture-specific.