Time delay in estimation of angles.

Summary.-The hypotheses were that a 2-min. delay as opposed to a 2-sec. delay between observation and mechanical estimation of an acute angle will increase the likelihood of overestimation of that angle and that minimal-surround cue-conditions would produce greater overestimation than maximal cue-conditions. 40 subjects esrimated a 54" acute angle presented behind a 2-way mirror in one of the four treatment combinations in a 2 x 2 factorial design. A 2-min. time delay caused significantly larger estimates of the angle. Overestimation in the maximal cue-condition was significant but the underestimate in the minimal cue-conditions was not. Cue-conditions were not significantly different from one another. Fisher (1969) and Maclean and Stacey (1971) have shown that larger acute angles typically are underestimated using construction or reproduction techniques. Ross (1972) has confirmed the findings in a series of studies on angle estimation. The effect seems to hold for lengthened and shortened angle arms, with the angle viewed with broad vistas, or through an artificial pupil, in lighted or darkened surrounds, and with the plane of the angle either perpendicular to the line of sight or tilted away in depth. Ross (1972), however, found overestimates of ecological acute angles in a diagonalspace parking lot when drivers were forced to estimate the angle while parking in the snow. The finding was consistent for children between 3 and 11 yr. of age, using a simulated parking lot and "matchbox" cars. The method best matches a sequential reproduction technique like the original technique used by Jastrow (Fisher, 1969) to show underestimation of acute angles. Ross (1973) also showed that greater degrees of overestimation are related to the likelihood that a perceived angle represents a three-dimensional corner seen suspended in space. He argued that the use of such a variable is necessary to explain fully the relative overestimation of horizontally oriented angles described by Fisher (1969) and Maclean and Stacey ( 197 1). The major untested variable in angle estimation studies is the time delay of the response. If the reliance upon long-term memory systems causes the driver to overestimate the parking angle then the implication is that cognitive events influence his perceptual judgment. In Ross' parking !ot studies the perception of the correct parking angle relied upon the driver's memory of that angle as seen on the previous days. Gregory (1971) and Segall, Campbell, and Herskovits (1966) both suggest that culturally based rectilinear ecologies influence perceptual responses. It follows that ang!e estimates should be overestimated in delayed-response conditions which require the subject to rely on his memory of the angle to be estimated. Maximum- and minimum-cue conditions were also explored (Maclean & Stacey, 1971) with the expectation that minimum-cue conditioas would lead to larger estimates. Forty men and women enrolled in general psychology were assigned to the treatment conditions randomly as they arrived for the study. The stimulus was produced by masking a light source so that a dim red 54" angle glowed on the far side of a two-way mirror. Angle arms were 11 mm in length; the subject sat in a darkened cubicle about 1 m from the window, with an angle another 20 mm beyond the window. For maximal-cue conditions the room containing the angle was illuminated allowing the subject to see Eoth the