Biomedical subjects

Daphne Maurer

Publications and source records attributed to Daphne Maurer.

5 recordsLinked to original sources

PubMed2003

Developmental changes in the processing of hierarchical shapes continue into adolescence.

The present study was designed to trace the normal development of local and global processing of hierarchical visual forms. We presented pairs of hierarchical shapes to children and adults and asked them to indicate whether the two shapes were the same or different at either the global or the local level. In Experiments 1 (6-year-olds, 10-year-olds, adults) and 2 (10-year-olds, 14-year-olds, adults), we presented stimuli centrally. All age groups responded faster on global trials than local trials (global precedence effect), but the bias was stronger in children and diminished to the adult level between 10 and 14 years of age. In Experiment 3 (10-year-olds, 14-year-olds, adults), we presented stimuli in the left or right visual field so that they were transmitted first to the contralateral hemisphere. All age groups responded faster on local trials when stimuli were presented in the right visual field (left hemisphere); reaction times on global trials were independent of visual field. The results of Experiment 3 suggest that by 10 years of age the hemispheres have adult-like specialization for the processing of hierarchical shapes, at least when attention is directed to the global versus local level. Nevertheless, their greater bias in Experiments 1 and 2 suggests that 10-year-olds are less able than adults to modulate attention to the output from local versus global channels-perhaps because they are less able to ignore distractors and perhaps because the cerebral hemispheres are less able to engage in parallel processing.

Adolescent↗

PubMed2002

The many faces of configural processing.

Adults' expertise in recognizing faces has been attributed to configural processing. We distinguish three types of configural processing: detecting the first-order relations that define faces (i.e. two eyes above a nose and mouth), holistic processing (glueing the features together into a gestalt), and processing second-order relations (i.e. the spacing among features). We provide evidence for their separability based on behavioral marker tasks, their sensitivity to experimental manipulations, and their patterns of development. We note that inversion affects each type of configural processing, not just sensitivity to second-order relations, and we review evidence on whether configural processing is unique to faces.

Journal Article↗

PubMed2002

Better perception of global motion after monocular than after binocular deprivation.

We used random-dot kinematograms to compare the effects of early monocular versus early binocular deprivation on the development of the perception of the direction of global motion. Patients had been visually deprived by a cataract in one or both eyes from birth or later after a history of normal visual experience. The discrimination of direction of global motion was significantly impaired after early visual deprivation. Surprisingly, impairments were significantly worse after early binocular deprivation than after early monocular deprivation, and the sensitive period was very short. The unexpectedly good results after monocular deprivation suggest that the higher centers involved in the integration of global motion profit from input to the nondeprived eye. These findings suggest that beyond the primary visual cortex, competitive interactions between the eyes can give way to collaborative interactions that enable a relative sparing of some visual functions after monocular deprivation.

Adolescent↗

PubMed2002

Sensitivity to global form in glass patterns after early visual deprivation in humans.

To compare the effects of early monocular versus early binocular deprivation on the perception of global form, we assessed sensitivity to global concentric structure in Glass patterns with varying ratios of paired signal dots to noise dots. Children who had been deprived by dense congenital cataracts in one (n=10) or both (n=8) eyes performed significantly worse than comparably aged children without eye problems. Consistent with previous results on sensitivity to global motion [Vision Research 42 (2002) 169], thresholds in the deprived eyes were significantly better after monocular deprivation than after binocular deprivation of comparable duration, even when there had been little patching of the nondeprived eye after monocular deprivation. Together, the results indicate that the competitive interactions between a deprived and nondeprived eye evident in the primary visual cortex can co-occur with complementary interactions in extrastriate cortex that enable a relative sparing of some visual functions after early monocular deprivation.

Adolescent↗

PubMed2002

Configural face processing develops more slowly than featural face processing.

Expertise in face processing takes many years to develop. To determine the contribution of different face-processing skills to this slow development, we altered a single face so as to create sets of faces designed to measure featural, configural, and contour processing. Within each set, faces differed only in the shape of the eyes and mouth (featural set), only in the spacing of the eyes and mouth (spacing set), or only in the shape of the external contour (contour set). We presented adults, and children aged 6, 8, and 10 years, with pairs of upright and inverted faces and instructed them to indicate whether the two faces were the same or different. Adults showed a larger inversion effect for the spacing set than for the featural and external contour sets, confirming that the spacing set taps configural processing. On the spacing set, all groups of children made more errors than adults. In contrast, on the external contour and featural sets, children at all ages were almost as accurate as adults, with no significant difference beginning at age 6 on the external contour set and beginning at age 10 on the featural set. Overall, the results indicate that adult expertise in configural processing is especially slow to develop.

Adolescent↗