Developmental disorders of vision

This review of developmental disorders of vision focuses on a few of the many disorders that disrupt visual development. Given the enormity of the human visual system in the primate brain and complexity of visual development, however, there are likely hundreds or thousands of potential types of disorders affecting high-level vision. The rapid progress seen in developmental dyslexia and Williams syndrome demonstrates the possibilities and difficulties inherent in researching such disorders, and the authors hope that similar progress will be made for congenital prosopagnosia and other disorders in the near future

It's all in the eyes: subcortical and cortical activation during grotesqueness perception in autism

Atypical face processing plays a key role in social interaction difficulties encountered by individuals with autism. In the current fMRI study, the Thatcher illusion was used to investigate several aspects of face processing in 20 young adults with high-functioning autism spectrum disorder (ASD) and 20 matched neurotypical controls. “Thatcherized” stimuli were modified at either the eyes or the mouth and participants discriminated between pairs of faces while cued to attend to either of these features in upright and inverted orientation. Behavioral data confirmed sensitivity to the illusion and intact configural processing in ASD. Directing attention towards the eyes vs. the mouth in upright faces in ASD led to (1) improved discrimination accuracy; (2) increased activation in areas involved in social and emotional processing; (3) increased activation in subcortical face-processing areas. Our findings show that when explicitly cued to attend to the eyes, activation of cortical areas involved in face processing, including its social and emotional aspects, can be enhanced in autism. This suggests that impairments in face processing in autism may be caused by a deficit in social attention, and that giving specific cues to attend to the eye-region when performing behavioral therapies aimed at improving social skills may result in a better outcome

Impaired body perception in developmental prosopagnosia

Developmental prosopagnosia (DP) is a lifelong neurodevelopmental disorder associated with difficulties recognising and discriminating faces. In some cases, the perceptual deficits seen in DP appear to be face-specific. However, DP is known to be a heterogeneous condition, and many cases undoubtedly exhibit impaired perception of other complex objects. There are several well-documented parallels between body and face perception; for example, faces and bodies are both thought to recruit holistic analysis and engage similar regions of visual cortex. In light of these similarities, individuals who exhibit face perception deficits, possibly due to impaired holistic processing or aberrant white matter connectivity, might also show co-occurring deficits of body perception. The present study therefore sought to investigate body perception in DP using a sensitive delayed match-to-sample task and a sizeable group of DPs. To determine whether body perception deficits, where observed, co-vary with wider object recognition deficits, observers’ face and body matching ability was compared with performance in a car matching condition. Relative to age-matched controls, the DP sample exhibited impaired body matching accuracy at the group level, and several members of the sample were impaired at the single-case level. Consistent with previous reports of wider object recognition difficulties, a number of the DPs also showed evidence of impaired car recognition

Prosopagnosia

Prosopagnosia is a cognitive disorder that affects one’s ability to recognize faces. Prosopagnosia can be caused by a congenital defect, or it can be acquired as a result of brain damage. Much research has been devoted to discovering the specific causes and effects of Prosopagnosia. Many case studies have been performed in order to determine the specific effects that each case of Prosopagnosia causes for various individuals suffering from the disease. This article discusses the various aspects of Prosopagnosia; specifically focusing on the behavioral, anatomical, and neurological implication

“A room full of strangers every day”: the psychosocial impact of developmental prosopagnosia on children and their families

Objective: Individuals with developmental prosopagnosia (‘face blindness’) have severe face recognition difficul¬ties due to a failure to develop the necessary visual mechanisms for recognizing faces. These difficulties occur in the absence of brain damage and despite normal low-level vision and intellect. Adults with developmental prosopagnosia report serious personal and emotional consequences from their inability to recognize faces, but little is known about the psychosocial consequences in childhood. Given the importance of face recognition in daily life, and the potential for unique social consequences of impaired face recognition in childhood, we sought to evaluate the impact of developmental prosopagnosia on children and their families. Methods: We conducted semi-structured interviews with 8 children with developmental prosopagnosia and their parents. A battery of face recognition tests was used to confirm the face recognition impairment reported by the parents of each child. We used thematic analysis to develop common themes among the psychosocial experiences of the children and their parents. Results: Three themes were developed from the child reports: 1) awareness of their difficulties, 2) coping strat¬egies, such as using non-facial cues to identify others, and 3) social implications, such as discomfort in, and avoid¬ance of, social situations. These themes were paralleled by the parent reports and highlight the unique social and practical challenges associated with childhood developmental prosopagnosia. Conclusion: Our findings indicate a need for increased awareness and treatment of developmental prosopagnosia to help these children manage their face recognition difficulties and to promote their social and emotional wellbein

Training face perception in developmental prosopagnosia through perceptual learning

Background: Recent work has shown that perceptual learning can improve face discrimination in subjects with acquired prosopagnosia. Objective: In this study, we administered the same program to determine if such training would improve face perception in developmental prosopagnosia.Method: We trained ten subjects with developmental prosopagnosia for several months with a program that required shape discrimination between morphed facial images, using a staircase procedure to keep training near each subject’s perceptual threshold. To promote ecological validity, training progressed from blocks of neutral faces in frontal view through increasing variations in view and expression. Five subjects did 11 weeks of a control television task before training, and the other five were re-assessed for maintenance of benefit 3 months after training. Results: Perceptual sensitivity for faces improved after training but did not improve after the control task. Improvement generalized to untrained expressions and views of these faces, and there was some evidence of transfer to new faces. Benefits were maintained over three months. Training also led to improvements on standard neuropsychological tests of short-term familiarity, and some subjects reported positive effects in daily life.Conclusion: We conclude that perceptual learning can lead to persistent improvements in face discrimination in developmental prosopagnosia. The strong generalization suggests that learning is occurring at the level of three-dimensional representations with some invariance for the dynamic effects of expression

A view of the world from a split-brain perspective

The extent to which observed behavior in the complete commissurotomy patients is supported by only one hemisphere would depend on individual differences interacting with a variety of factors such as genetics, intelligence, and so on. The lesson imparted here is that there is sufficient functional redundancy in the neocortex so that the capacity to maintain a wide range of abilities is within the control of one hemisphere. And, yet, as seen in what is missing in the patients' behavior, one hemisphere is not quite enough. Nature seems to have intended that the two hemispheres complement each other, that the full range of human behavior be best accomplished through interaction between the left and right hemispheres

Do Humans Prefer Faces? Zygomatic Muscle Responses to Neutral Faces vs. Neutral Objects

The present study examined the significance of viewing images of neutral faces versus images of neutral objects on zygomatic muscle activity using facial EMG. Participants (60% women) from a pool of introductory psychology courses had their facial EMG recordings measured in response to images of neutral faces and neutral objects. Participants’ valence rating of each image was also recorded using the Self-Assessment Manikin (SAM) in order to rate their emotional response to each image. The primary hypothesis was that participants would have greater activity in the zygomatic muscle region when presented with images of neutral faces as opposed to lessor activity when presented with images of neutral objects. It was also hypothesized that if participants preferred seeing images of faces as compared to objects, their positive feelings would produce higher SAM ratings. Results from the present study indicated images of neutral faces showed no significant difference in EMG activity compared to images of neutral objects. Self-report data also showed no significant difference in pleasantness or emotional valence between ratings of neutral faces and ratings of neutral objects