The biasing of figure-ground assignment by shading cues for objects and faces in prosopagnosia.

Prosopagnosia is defined by impaired recognition of the identity of specific faces. Whether the perception of faces at the categorical level (recognizing that a face is a face) is also impaired to a lesser degree is unclear. We examined whether prosopagnosia is associated with impaired detection of facial contours in a bistable display, by testing a series of five prosopagnosic patients on a variation of Rubin's vase illusion, in which shading was introduced to bias perception towards either the face or the vase.

Spatial processing in Bálint syndrome and prosopagnosia: a study of three patients.

Background: Spatial analysis may be subdivided into between-object and within-object spatial coding. We investigated the contribution of various visual cues to grouping processes that might determine whether single or multiple objects were perceived and therefore which type of spatial coding would be used for a stimulus.

Methods: We asked three patients to make shape judgments with a series of displays showing triangular arrangements, moving from more implicit triangles defined by separate objects at the apices (between-object spatial coding) to more explicit triangles with line edges or surface texture (within-object spatial coding).

Investigations of face expertise in the social developmental disorders.

Background: Patients with social developmental disorders (SDD), also known as autism spectrum disorders, may have impaired recognition of facial identity or facial expressions.

Objective: Our goal was to determine whether SDDs were characterized by loss of a perceptual mechanism responsible for face expertise, as current theories suggest that such a loss should be selective for upright faces, disproportionately affect the perception of facial configuration, and possibly be more severe in the eye region.

Method: We tested a group of 24 adult patients with SDD with an oddity paradigm that required them to detect changes in facial configuration or feature color, in either the eyes or the mouth, in both upright and inverted faces.

Perception of facial expression and facial identity in subjects with social developmental disorders.

Background: It has been hypothesized that the social dysfunction in social developmental disorders (SDDs), such as autism, Asperger disorder, and the socioemotional processing disorder, impairs the acquisition of normal face-processing skills. The authors investigated whether this purported perceptual deficit was generalized to both facial expression and facial identity or whether these different types of facial perception were dissociated in SDDs.

Methods: They studied 26 adults with a variety of SDD diagnoses, assessing their ability to discriminate famous from anonymous faces, their perception of emotional expression from facial and nonfacial cues, and the relationship between these abilities.

Switching, plasticity, and prediction in a saccadic task-switch paradigm.

Several cognitive processes are involved in task-switching. Using a prosaccade/antisaccade paradigm, we manipulated both the interval available for preparation between the cue and the target and the predictability of trial sequences, to isolate the contributions of foreknowledge, an active switching (reconfiguration) process, and passive inhibitory effects persisting from the prior trial. We tested 15 subjects with both a random and a regularly alternating trial sequence.

The field defects of anterior temporal lobectomy: a quantitative reassessment of Meyer's loop.

Temporal lobectomy is often complicated by superior quadrantanopia. The relation of field loss to sagittal resection length can inform us about the functional anatomy of Meyer's loop, with ramifications for surgical planning. However, the literature has produced highly variable results.

The covert priming effect of faces in prosopagnosia.

Background: There are many methods of testing covert face recognition in prosopagnosia, but it is not clear whether different types of covert recognition share a common mechanism.

Objective: To determine whether direct forced-choice techniques and indirect face-priming methods yielded similar behavioral estimates of covert ability in a series of prosopagnosic patients.

Methods: The authors tested seven control subjects and seven prosopagnosic patients.

Are patients with social developmental disorders prosopagnosic? Perceptual heterogeneity in the Asperger and socio-emotional processing disorders.

It has been hypothesized that social developmental disorders (SDD) like autism, Asperger's disorder and the social-emotional processing disorder may be associated with prosopagnosic-like deficits in face recognition. We studied the ability to recognize famous faces in 24 adults with a variety of SDD diagnoses. We also measured their ability to discriminate changes in internal facial configuration, a perceptual function that is important in face recognition, and their imagery for famous faces, an index of their facial memory stores.