Biomedical subjects

J Avrahami

Publications and source records attributed to J Avrahami.

3 recordsLinked to original sources

PubMed1999

Objects of attention, objects of perception.

Four experiments were conducted, to explore the notion of objects in perception. Taking as a starting point the effects of display content on rapid attention transfer and manipulating curvature, closure, and processing time, a link between objects of attention and objects of perception is proposed. In Experiment 1, a number of parallel, equally spaced, straight lines facilitated attention transfer along the lines, relative to transfer across the lines. In Experiment 2, with curved, closed-contour shapes, no "same-object" facilitation was observed. However, when a longer time interval was provided, in Experiment 3, a same-object advantage started to emerge. In Experiment 4, using the same curved shapes but in a non-speeded distance estimation task, a strong effect of objects was observed. It is argued that attention transfer is facilitated by line tracing but that line tracing is encouraged by objects.

Adult↗

PubMed1998

Presence and absence of top and right advantage as an indication of the attentional strategies underlying object selection.

To explore the conditions in which an object is selected in its entirety and better understand the process underlying such selection, a target, lying on the contour of an outline figure, was judged. Target position on the figure was either known or not known throughout a block of trials, and various properties of the figure itself--continuity, familiarity, and contrast--were manipulated. The pattern of results can best be accounted for by assuming that object selection involves a scan, beginning at the top-right end and terminating only when the bottom-left end is reached. Partial selection could have occurred only for the top and the right positions when the target was known always to be there. As to the manipulated properties, none interacted with knowledge of target position, indicating that they did not affect the process of selection. Most importantly, partial selection was not facilitated even in the discontinuous condition, in which the figure consisted of two separate elements.

Computer Graphics↗

PubMed1994

The emergence of events.

Although the concept of an event is widely used as the basic unit in the organization of experience, memory and meaning, little attention has been paid to how events emerge or what determines the boundaries of an event. It is usually taken for granted that one knows what an event is or how events are demarcated. In this paper an explanation is offered for the emergence of events, the cut hypothesis, which states: "A sub-sequence of stimuli is cut out of a sequence to become a cognitive entity if it has been experienced many times in different contexts", and three experiments to demonstrate the predictive power of the hypothesis are described. The stimuli in all three experiments were video films, constructed by randomly assembling short excerpts from movies. In the first experiment the cut hypothesis was juxtaposed with the thesis of demarcation at major changes, and it was shown that, after experiencing a certain repeating sequence, subjects hardly considered dividing at an internal point, even if it was a point of maximal change; points of maximal change were determined on the basis of performance by control subjects who did not experience the repeating sequence. In the second experiment the cut hypothesis was juxtaposed with an associationistic explanation; it was shown that subjects who viewed a certain sequence repeating in variable contexts recognized it better than subjects who had viewed the same sequence repeating always in the same context. In the third experiment a prediction of the hypothesis on recall behaviour was tested and it was shown that experience with sequences of stimuli repeating in various contexts results in cohesion of their elements.

Cognition↗