Biomedical subjects

R Rettenbach

Publications and source records attributed to R Rettenbach.

3 recordsLinked to original sources

PubMed1998

Parallel visual search is not always effortless.

Serial visual search can become parallel with practice. We tested whether this parallelisation is accompanied by a transition from an attentive to a pre-attentive and thus effortless mode of visual perception. While psychophysiological indicators of attentional effort (galvanic skin conductance, muscle tonus) reflected the distinction between serial and parallel search modes, they did not follow the perceptual changes during learning. Despite the perceptual parallelisation with practice, the attentional load remained high for initially serial tasks.

Attention↗

PubMed1996

[Texture discrimination and visual search: development, learning and plasticity].

BACKGROUND: The abilities to segment coherent surfaces out of a discrepant background (texture segmentation) and to localize single objects out of a complex scene (visual search) are believed to occur at a peripheral level in the cortical visual pathway. AIM OF THE STUDY: Are texture segmentation and visual search innate or acquired? Can these abilities be improved in adulthood by learning? Does a disturbed early visual experience (strabismus, amblyopia) lead to a reduction of these abilities? RESULTS: Texture segmentation and visual search undergo a protracted development which continues well into adulthood. Even in adult observers, these abilities can be improved with practice. Learning is enduring, but not specific: It can be transferred from one task to another and between the two eyes of a given subject (including the two eyes of stereoblind subjects). DISCUSSION: We conclude that learning of texture segmentation and visual search does not involve the specific features of a visual scene, but rather reflects an improved strategy of localizing visual objects in a cluttered environment. This type of learning probably occurs at a very high level of cortical processing.

Adolescent↗

PubMed1995

Perceptual learning in visual search: fast, enduring, but non-specific.

Visual search has been suggested as a tool for isolating visual primitives. Elementary "features" were proposed to involve parallel search, while serial search is necessary for items without a "feature" status, or, in some cases, for conjunctions of "features". In this study, we investigated the role of practice in visual search tasks. We found that, under some circumstances, initially serial tasks can become parallel after a few hundred trials. Learning in visual search is far less specific than learning of visual discriminations and hyperacuity, suggesting that it takes place at another level in the central visual pathway, involving different neural circuits.

Discrimination, Psychological↗