The shift effect can be elicited with both foveal and peripheral masks

Mattingley, Jason B.; Badcock, David R.

doi:10.1016/0042-6989(91)90049-b

Cited by 5 publications

(1 citation statement)

References 31 publications

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“…Since other characteristics of the periphery effect observed in cat and monkey have been verified psychophysically in humans (Derrington, 1984;Bowling, 1985;Mattingly & Badcock, 1991;Fuhr & Kuyk, 1998), we expect to find the periphery effect in humans to cross over the vertical meridian. We also predict that when the remote stimulus (the mask) and test are separated by the same amount the periphery effect will be of the same magnitude regardless of whether or not the masking grating and test spot are on the same or opposite sides of the vertical meridian.…”

Section: Introductionmentioning

confidence: 57%

The psychophysical periphery effect crosses the vertical meridian

Kuyk

Niculescu

2001

Vis Neurosci

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This study measured the periphery effect and compared its magnitude when the peripheral stimulation was on the same or opposite side of the vertical meridian as the test spot. Test thresholds for a 1.5-deg diameter, 8-ms spot located 1.75 deg to one side of the vertical meridian were elevated by approximately 0.125 log units when a 0.25 cycles/deg (cpd) counterphased grating was presented at a similar eccentric offset on the other side of the vertical meridian. The periphery effect disappeared when the test spot was moved outward to 8-deg eccentricity. When the grating and test were presented on the same side of the vertical meridian, test thresholds at both retinal locations were elevated by the same amount, 0.2 log units. Consistent with the physiology in cat retina, the periphery effect in humans also crosses over the vertical meridian. However, the effect is small and the test spot must be in close proximity to the vertical meridian for it to be observed. Also, the crossover periphery effect is reduced in magnitude by 37.5% compared to when the grating and test are presented on the same side of the vertical meridian. This suggests there may be a difference in how the underlying neural mechanism that transmits the periphery effect signal laterally is organized for sending the periphery effect signal across the vertical meridian as compared to within a retinal hemifield.

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Section: Introductionmentioning

confidence: 57%

The psychophysical periphery effect crosses the vertical meridian

Kuyk

Niculescu

2001

Vis Neurosci

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Specific effects of the benzodiazepine midazolam on visual receptive fields in light and dark adapted human subjects

et al. 1992

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Psychophysical experiments in humans have revealed similar characteristics of visual receptive fields as were found in cats and monkeys from retinal ganglion cell recordings. In addition, in some retinal ganglion cells of cats the GABA antagonist bicuculline decreases the activity of the inhibitory surround. These findings led to two predicitions: 1) benzodiazepines will selectively increase the inhibitory surround of human visual receptive fields, 2) after dark adaptation, no free GABA will be available in the synapses and benzodiazepines will have no effect on the visual system. Characteristics of human receptive fields were determined by subthreshold summation: the contrast threshold of a vertical line was measured dependent on the distance of two parallel flanking lines whose contrast was below threshold. Both hypotheses were confirmed: the threshold in the inhibitory region of receptive fields was specifically increased in a dose-dependent manner by midazolam PO (7.5 mg: P < 0.05; 15 mg: P < 0.01). In dark-adapted subjects no effect of midazolam was found. Control experiments with atropine (1 mg IV), sulpiride (100 mg IM), and levodopa (100 mg PO) showed no specific effect. The visual system may be a model to bridge the gap between animal and human psychopharmacology.

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Sudden and gradual presentation of distractor objects: differential interference effects

Castiello

Badcock²,

Bennett

1999

Experimental Brain Research

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In solving the selection-for-action problem, it is believed that attentional mechanisms enable dominance of target over non-target objects. However, under some conditions, information from non-target objects "interferes" with the action to a relevant target. We investigated the possibility that this interference may result when the irrelevant object activates a specific subset of visuomotor pathways. Participants reached to grasp three-dimensional stimuli while actively attending to a nearby flanker object. The means by which the flanker was presented was manipulated. This relevant object was illuminated either abruptly or gradually. The parvocellular pathway in early visual processing is equally activated in both conditions. The magnocellular pathway is strongly activated by abrupt presentation and weakly activated with gradual presentation of the flanker object. Kinematics of the reach-to-grasp action to the target showed signs of interference only in the sudden illumination condition. This suggests a dissociation between dorsal and ventral cortical streams in terms of relevance for action. Our data suggests that this effect is not due to early visual-pathway differences, but instead reveals a property of a transient object-based visual attention mechanism.

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The shift effect can be elicited with both foveal and peripheral masks

Cited by 5 publications

References 31 publications

The psychophysical periphery effect crosses the vertical meridian

The psychophysical periphery effect crosses the vertical meridian

Specific effects of the benzodiazepine midazolam on visual receptive fields in light and dark adapted human subjects

Sudden and gradual presentation of distractor objects: differential interference effects

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