Visual curve tracing properties.

Abstract

Subjects decided whether 2 dots were on the same curve or 2 different curves, and the curvature of the curves or the proximity of other (distractor) curves to the target curve was varied. Response time increased as the arc length of the curve connecting the 2 dots increased, suggesting that the curve was traced to perform the task. Tracing rate was faster for low- than high-curvature contours and was increasingly slower as distractor contours were increasingly proximal to the traced curve. Proximity results were predicted by a model in which response time depends on the ratio of the distance between the dots and the distance between adjacent lines. Curve tracing operations used to integrate information along contours are sensitive to several properties of the contours. The implications of the sensitivity of tracing operations to these curve properties are discussed.

A gradual spread of attention

“…Reaction times increased significantly with each additional intersection between the target and the distractor curves, showing that contour grouping can be time consuming (see also Jolicoeur et al, 1986Jolicoeur et al, , 1991Scholte et al, 2001).…”

Fundamental Measurement of Perceived Length and Perceived Area

“…The remaining participants reported concatenating one centimeter along the circumference without mentally straightening the circumference. Participants can compare distances along curves by mentally tracing the curves (Jolicoeur, Ullman, & Mackay, 1991;Pringle & Egeth, 1988). It is undecided whether the participants in the present study tried to verbalize mental tracing or a mental operation specific to the judgment task such as mental straightening.…”

On Distinguishing Epistemic from Pragmatic Action

“…In about 1% of the cases when a player drops a zoid, the act of dropping is preceded by a behavioral routine of transIating the zoid to the wall and then back again (see Figure 14). Because the accuracy of judging spatia1 reiationships between visuahy presented stimuli varies with the distance between the stimuli (Joficoeur, Ullman, & Mackay, 1991), a zoid dropped from a height of 15 squares has a greater chance of landing in a mistaken column than a zoid dropped from a height of 3 squares. Thus, the obvious function of this translate-to-wall routine is to verify the column of the zoid.…”