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N Weisstein

Publications and source records attributed to N Weisstein.

12 recordsLinked to original sources
PubMed1992

Visual search for simple volumetric shapes.

Five experiments measured reaction time (RT) to detect the presence or absence of a simple volumetric shape (target) dependent on the number of display items (distractors) and their depicted three-dimensional (3-D) orientation. Experiments 1-4 examined every pairwise combination of two different simple volumetric shapes in two 3-D orientations. Conditions exhibiting "pop-out" could be predicted by differences in their two-dimensional (2-D) features. Conditions in which search was slower support previously found search asymmetries for particular 2-D features. When the distractors were a mixture of the other shapes in the same 3-D orientation, search was serial, except when the target had a curved principal axis (Experiment 5). The results suggest that these simple volumetric shapes are not processed preattentively.

Adult↗
PubMed1991

Conflicting figure--ground and depth information reduces moving phantom visibility.

Moving phantom visibility was measured in two experiments where the global figure-ground and depth relations within phantom-inducing patterns were manipulated. The local inducing environment where the illusion occurred was identical for all patterns. Phantom visibility was significantly reduced when occlusion cues specified the phantom-inducing parts of a pattern as ground. These results suggest conflicting figure-ground and depth information interferes with the representation and perception of phantoms as figure regions.

Adult↗
PubMed1989

Figure and ground in space and time: 1. Temporal response surfaces of perceptual organization.

The figure-ground organization of an ambiguous bipartite pattern can be manipulated by altering the temporal-frequency content of the two regions of the pattern. Ambiguous patterns in which the two regions of each pattern contained sine-wave gratings of either 8, 4, 1, or 0.5 cycles deg-1 undergoing contrast reversal at rates of 0, 3.75, 7.5, or 15 Hz were tested for figure-ground organization under conditions of equated space-averaged and time-averaged luminance and perceived contrast. All combinations of temporal-frequency differences between the two regions were tested at each spatial frequency. The data are reported for two levels of temporal resolution (15 and 30 s). The pattern region with the relatively higher temporal frequency tended to be seen as the background a higher percentage of the viewing time. There were significant linear trends for the appearance as background of the region of higher temporal frequency with respect to the magnitude of the temporal-frequency difference between the two regions of each pattern for all spatial frequencies and data intervals except the final 15 s interval of the lowest (0.5 cycle deg-1) spatial-frequency condition.

Form Perception↗
PubMed1989

Figure and ground in space and time: 2. Frequency, velocity, and perceptual organization.

The figure-ground organization of an ambiguous bipartite pattern in which the two regions of the pattern contained sine-wave gratings which differed in spatial frequency was examined for two pairs of spatial frequencies: 1 and 4 cycles deg-1, and 1 and 8 cycles deg-1. The region of higher spatial frequency underwent contrast reversal at one of four rates: 0, 3.75, 7.5, or 15 Hz. The region of lower spatial frequency was equated with either the temporal frequency or the velocity of the grating of higher spatial frequency in three sets of conditions: one stationary condition, three in which temporal frequency was equated, and three in which velocity was equated. For the 1 and 4 cycles deg-1 pair, the region of lower spatial frequency tended to be seen as the background a higher percentage of the time. There were significant linear trends for the appearance as background of the region of lower spatial frequency with respect to the magnitude of the velocity difference between the two regions of the pattern. The faster the 1 cycle deg-1 grating moved with respect to the 4 cycles deg-1 grating, the higher the percentage of the time it was seen as the ground. The results for the 1 and 8 cycles deg-1 pair were in some cases unexpected in that the 8 cycles deg-1 grating was seen as the ground behind the 1 cycle deg-1 grating even though it was of a higher spatial frequency and moved at a slower velocity. The spatiotemporal tuning of the visual system is discussed.

Form Perception↗
PubMed1989

Spatial and temporal frequency in figure-ground organization.

Figure-ground organization of an ambiguous pattern can be manipulated by the spatial and temporal frequency content of the two regions of the pattern. Controlling for space-averaged luminance and perceived contrast, we tested patterns in which the two regions of the ambiguous pattern contained sine-wave gratings of 8, 4, 1, or 0.5 cycles per degree (cpd) undergoing on:off flicker at the rates of 0, 3.75, 7.5, or 15 Hz. For a full set of combinations of temporal frequency differences, with each spatial frequency the higher temporal frequency was seen as background for more of the viewing time. For two spatial frequency combinations, 1 and 4 cpd, and 1 and 8 cpd, tested under each of the four temporal frequencies, the lower spatial frequency region was seen as the background for more of the viewing time. When the effects of spatial and temporal frequency were set in opposition, neither was predominant in determining perceptual organization. It is suggested that figure-ground organization may parallel the sustained-transient response characteristics of the visual system.

Attention↗
PubMed1977

A phantom-motion aftereffect.

Motion aftereffects, typically found to result only from localized retinal stimulation, were obtained within regions of the visual field that had not been stimulated by moving contours. "Phantom" stripes are seen moving through a physically homogeneous (empty) region of the visual field when vertical stripes move above and below that region. Immediately afterward, stationary stripes in the previously empty region appear to move in the opposite direction. This phantom-motion aftereffect provides a novel instance of the way global structure affects processes that have been assumed to be influenced only by simpler local spatial and temporal variables.

Afterimage↗
PubMed1976

Adventures of a woman in science.

This paper is divided into two parts. The first part describes the difficulties encountered in entering the scientific profession and staying there if one is a woman; the difficulties in combating the degrading sterotypes about women that are commonly held (women are believed to be submissive, unintelligent, uncreative, etc.); and the discrimination that accompanies beliefs in these sterotypes. The second part of the paper examines the evidence for the truth or falsity of the proposition that these stereotypes reflect woman's "innate" nature, and shows that there is no evidence to suggest that the proposition is true. On the other hand, there is evidence from social psychology that, for the most part, people act the way people around them expect them to act, and they believe that they are what others expect them to be. So if the scientific profession holds the outragious and erroneous belief that women can't be scientists, it is likely that few women will become scientists. This must change: the integrity of the progession is at stake.

Female↗