CONTRAST-BASED DIGITAL TRACKING VERSUS HUMAN OBSERVERS IN STUDIES OF ANIMAL LOCOMOTION

The availability of relatively inexpensive digital contrast detection creates the possibility of automated, general-purpose motion tracking, equally applicable to concurrent remote video observation and analysis of videotape recordings. In this study, a digital method of scoring locomotor activity in a laboratory arena was compared with scoring by human observers. The digital tracking device (HVS VP-112) utilized foreground/background contrast to determine subject location from a video image; human observers scored from videotape. In addition, relative floor brightness (red lighting was held constant) was manipulated to compare the efficiency of the digital tracking system’s ability to detect a moving subject under different contrast conditions. The arena had a reversible floor, with opposite sides dark gray and white. Six subjects (male Long-Evans Rattus norvegiens, 4 months old) were given opportunity to enter the arena for the first 2 days on the white floor; the floor was reversed for the 3rd day. Six matched subjects followed an opposite schedule. Recorded measures of zone changes, made by digital tracking and by humans, were highly correlated (r =.951, p <.001) and not significantly different. Activity level, as measured by number of entries, latency to enter, and total time in the arena, was significantly higher in subjects for which the dark floor was showing on Day 1. Although these scoring methods produced comparable results, requisite constraints on experimental procedures may limit the usefulness of this type of tracking device. © 1990, The Psychonomic Society, Inc.. All rights reserved.