Biomedical subjects

Galit Yovel

Publications and source records attributed to Galit Yovel.

4 recordsLinked to original sources

PubMed2004

Face perception: domain specific, not process specific.

Evidence that face perception is mediated by special cognitive and neural mechanisms comes from fMRI studies of the fusiform face area (FFA) and behavioral studies of the face inversion effect. Here, we used these two methods to ask whether face perception mechanisms are stimulus specific, process specific, or both. Subjects discriminated pairs of upright or inverted faces or house stimuli that differed in either the spatial distance among parts (configuration) or the shape of the parts. The FFA showed a much higher response to faces than to houses, but no preference for the configuration task over the part task. Similarly, the behavioral inversion effect was as large in the part task as the configuration task for faces, but absent in both part and configuration tasks for houses. These findings indicate that face perception mechanisms are not process specific for parts or configuration but are domain specific for face stimuli per se.

Brain↗

PubMed2004

The neural basis of the butcher-on-the-bus phenomenon: when a face seems familiar but is not remembered.

A common distinction in contemporary research on episodic memory is between familiarity, an unsubstantiated impression that an event was experienced previously, and recollection, remembering some information plus the spatiotemporal context of the episode in which it was acquired. The epitome of pure familiarity--the butcher-on-the-bus phenomenon--occurs when one believes that a person is familiar (often upon seeing their face in an atypical context) while failing to recall any information about that person whatsoever. Prior research on familiarity and recollection has relied on verbal material. Whereas word meanings and pronunciations are well learned in advance, here we produced pure familiarity and recollection using photographs of faces never seen before the experiment. When participants recognized a face, recollection was inferred if they also remembered either the occupation associated with that face earlier in the experiment or any other episodic detail. Pure familiarity was inferred when recognition occurred in the absence of any such contextual retrieval. Analyses of brain potentials recorded during initial encoding showed that right-sided neural activity predicted subsequent face familiarity, whereas bilateral potentials predicted subsequent face recollection. Results during memory testing were inconsistent with the popular idea that familiarity is generically indexed by reduced frontal N400-like potentials. Instead, both memory experiences were associated with bilateral, parietal-maximum brain potentials, although with smaller amplitudes and for a shorter duration for familiarity. These similarities between electrophysiological correlates of pure familiarity and recollection suggest that familiarity with faces may arise by virtue of a subset of the neural processing responsible for recollection.

Adolescent↗

PubMed2003

Neural correlates of the left-visual-field superiority in face perception appear at multiple stages of face processing.

Studies in healthy individuals and split-brain patients have shown that the representation of facial information from the left visual field (LVF) is better than the representation of facial information from the right visual field (RVF). To investigate the neurophysiological basis of this LVF superiority in face perception, we recorded event-related potentials (ERPs) to centrally presented face stimuli in which relevant facial information is present bilaterally (B faces) or only in the left (L faces) or the right (R faces) visual field. Behavioral findings showed best performance for B faces and, in line with the LVF superiority, better performance for L than R faces. Evoked potentials to B, L, and R faces at 100- to 150-msec poststimulus showed no evidence of asymmetric transfer of information between the hemispheres at early stages of visual processing, suggesting that this factor is not responsible for the LVF superiority. Neural correlates of the LVF superiority, however, were manifested in a shorter latency of the face-specific N170 component to L than R faces and in a larger amplitude to L than R faces at 220-280 and 400-600 msec over both hemispheres. These ERP amplitude differences between L and R faces covaried across subjects with the extent to which the face-specific N170 component was larger over the right than the left hemisphere. We conclude that the two hemispheres exchange information symmetrically at early stages of face processing and together generate a shared facial representation, which is better when facial information is directly presented to the right hemisphere (RH; L faces) than to the left hemisphere (LH; R faces) and best when both hemispheres receive facial information (B faces).

Adult↗

PubMed2003

Facilitation and disruption of lateralized syllable processing by unattended stimuli in the opposite visual field.

The influence of lateralized unattended stimuli on the processing of attended stimuli in the opposite visual field can shed light on the nature of information that is transferred between hemispheres. On a cued bilateral task, participants tried to identify a syllable in the attended visual field, which elicits a left hemisphere (LH) advantage and different processing strategies by the two hemispheres. The same or a different syllable or a neutral stimulus appeared in the unattended field. Transmission of unattended syllable codes between hemispheres is symmetric, as revealed by equal interference for the two visual fields. The LH is more accurate than the RH in encoding unattended syllables, as indicated by facilitation in the left but not right visual field and a greater frequency of identifiable intrusions into the left than right field. However, asymmetric encoding strategies are different for attended and unattended syllables.

Attention↗