Biomedical subjects

A von Mühlenen

Publications and source records attributed to A von Mühlenen.

11 recordsLinked to original sources

PubMed2001

Visual search for motion-form conjunctions: is form discriminated within the motion system?

Motion-form conjunction search can be more efficient when the target is moving (a moving 45 degrees tilted line among moving vertical and stationary 45 degrees tilted lines) rather than stationary. This asymmetry may be due to aspects of form being discriminated within a motion system representing only moving items, whereas discrimination of stationary items relies on a static form system (J. Driver & P. McLeod, 1992). Alternatively, it may be due to search exploiting differential motion velocity and direction signals generated by the moving-target and distractor lines. To decide between these alternatives, 4 experiments systematically varied the motion-signal information conveyed by the moving target and distractors while keeping their form difference salient. Moving-target search was found to be facilitated only when differential motion-signal information was available. Thus, there is no need to assume that form is discriminated within the motion system.

Adolescent↗

PubMed2000

Probing distractor inhibition in visual search: inhibition of return.

The role of inhibition of return (IOR) in serial visual search was reinvestigated using R. Klein's (1988) paradigm of a search task followed by a probe-detection task. Probes were presented at either the location of a potentially inhibited search distractor or an empty location. No evidence of IOR was obtained when the search objects were removed after the search-task response. But when the search objects remained on, a pattern of effects similar to Klein's results emerged. However, when just the search-critical object parts were removed or when participants received immediate error feedback to prevent rechecking of the search objects, IOR effects were observed only when probes appeared equally likely at search array and empty locations. These results support the operation of object-based IOR in serial visual search, with IOR demonstrable only when rechecking is prevented (facilitating task switching) and monitoring for probes is not biased toward search objects.

Adolescent↗

PubMed2000

Perceptual integration of motion and form information: evidence of parallel-continuous processing.

In three visual search experiments, the processes involved in the efficient detection of motion-form conjunction targets were investigated. Experiment 1 was designed to estimate the relative contributions of stationary and moving nontargets to the search rate. Search rates were primarily determined by the number of moving nontargets; stationary nontargets sharing the target form also exerted a significant effect, but this was only about half as strong as that of moving nontargets; stationary nontargets not sharing the target form had little influence. In Experiments 2 and 3, the effects of display factors influencing the visual (form) quality of moving items (movement speed and item size) were examined. Increasing the speed of the moving items (> 1.5 degrees/sec) facilitated target detection when the task required segregation of the moving from the stationary items. When no segregation was necessary, increasing the movement speed impaired performance: With large display items, motion speed had little effect on target detection, but with small items, search efficiency declined when items moved faster than 1.5 degrees/sec. This pattern indicates that moving nontargets exert a strong effect on the search rate (Experiment 1) because of the loss of visual quality for moving items above a certain movement speed. A parallel-continuous processing account of motion-form conjunction search is proposed, which combines aspects of Guided Search (Wolfe, 1994) and attentional engagement theory (Duncan & Humphreys, 1989).

Adolescent↗

PubMed1996

Attentional tracking and inhibition of return in dynamic displays.

Seven experiments were conducted to replicate, and extend, a finding by Tipper, Driver, and Weaver (1991). They reported evidence for dynamic, object-centered inhibition of return (IOR)--that is, coding of inhibition following a peripheral cue in coordinates that move with the previously cued object, providing a dynamic bias against reattending to that object. The present experiments used a variation of Posner and Cohen's (1984) spatial cuing paradigm. Subjects responded manually (simple reaction time) to a luminance increment in one of two peripheral boxes, one of which had previously been cued (brightened). Experiments 1, 2, and 5 replicated the standard (environmental) IOR effect when the display was stationary. IOR was more marked for right-side targets than for left-side targets and tended to be affected by the compatibility between response hand and (cued) target position. However, when the boxes moved around the display center (Experiments 1, 2, 3, 4, 6, and 7), contrary to Tipper et al., there was no evidence of dynamic, object-centered IOR. Rather, there was strong evidence of attentive tracking of whatever box happened to move from left to right, irrespective of the direction of its motion (clockwise or counterclockwise) and whether it was more likely to contain the target than the other (right-to-left moving) box. There was a tendency for left-to-right tracking to be more marked with right-hand responses, pointing to the existence of a dynamic stimulus-response compatibility effect. The implications of the present findings for the role of attentive tracking and IOR in dynamic scenes are discussed.

Adolescent↗

PubMed1973