Effect of frequency of target intermittence upon tracking.

Abstract

Measures of proficiency of tracking on the Pedestal Sight Manipulation Test were obtained at frequencies of intermittent target presentation of 2,4,6,8,10,12, and 14 cps and a steady state condition above fusion (16 cps). The brightness of the target was held constant for all conditions at .548 ml. and the light-dark ratio for each of the frequencies was 50/50. Two experiments were performed. In one, 10 Ss each received 8 trials of practice for one of the 8 conditions of target presentation. In the other, 2 Ss were selected at random from each of the 8 groups of the first experiment and these 16 Ss received two practice trials on each of the 8 target conditions as determined by an 8 x 8 latin square. Although measures of tracking proficiency were obtained for azimuth (A), elevation (E), range (R), azimuth and elevation (AE), and azimuth, elevation, and range (AER), because of the similarity of results over these separate measures, only the AE and AER data were analyzed completely and presented. Analysis of variance demonstrated a significant effect of frequency of intermittent presentation of the target on tracking. Further statistical analysis revealed the relations to be linear, tracking proficiency increasing with increase in frequency of intermittent presentation of the target. Least-square regression equations were fitted separately to the AE and AER data for the 2 experiments. Although slope is essentially the same for the several conditions, the y intercept differs as a function of the measure of tracking (AE vs. AER) and of amount of practice (EXP 1 vs Exp. 2). The results are discussed especially in relation to those of a prior experiment by Battig, Gregg, Nagel, Small, and Brogden.