Intratrial proactive interference in rats’ serial alternation performance in the radial maze

Abstract

Rats acquired a serial alternation task in an eight-arm radial maze that was partitioned into four pairs of arms. Each pair was associated with a different distal stimulus. Rats were initially forced to the left or right arm in each pair (the study segment) before being exposed to both arms in each pair (the freechoice or test segment). Only the previously blocked arm of each pair remained baited. Following initial training, proactive interference (PI) was induced by presenting rats with a forced-choice (prestudy) segment containing arm positions opposite those in the subsequent study segment. Such trials generated poorer free-choice accuracy than did trials without a prestudy segment. Forcing rats to both arms in the pair in a prestudy segment produced only transient PI. A slight improvement in rats' free-choice performance was obtained by forcing them to the same arm position, but only when the test segment was delayed by 30 min. Increasing the interval between the prestudy and study segments from 2 to 30 min eliminated PI, but only when free-choice testing was delayed by 2 min rather than by 30 min. These results suggest that intratrial PI in this preparation was primarily due to confusion about which arm position in each pair had been visited during the last forced-choice segment.

Changing room cues reduces the effects of proactive interference in Clark's Nutcrackers, Nucifraga columbiana.

“…This agrees with past research on proactive and retroactive interference with rats in a radial arm maze. Rats’ performance on a radial maze declines when they are exposed to extra visits to arms within the same maze (Hoffman & Maki, 1986; Cohen et al, 1996). However, this interference can be reduced if rats are tested in a separate maze than the test maze (Beatty & Shavalia, 1980; Cook, & Brown, 1985; Maki, Brokofsky & Burg, 1979).…”

“…Nutcrackers made more errors when recalling a list of spatial locations if they had previously been tested with a spatial list the same day (Lewis & Kamil, 2006). Despite the nutcracker’s impressive memory abilities (e.g., Bednekoff, Kamil, & Balda, 1997; Balda & Kamil, 1992; Tomback, 1980; Vander Wall & Hutchins, 1983), they are still susceptible to interference in the laboratory like many other nonhuman species such as rats and pigeons (e.g., Cohen, Sturdy, & Hicks, 1996; Grant, 1981; Hoffman & Maki, 1986; Roberts & Dale, 1981). …”

The Effects of Reward Omission and Change on Proactive Interference in Spatial Alternation

“…The alternation task differs from delayed matching in that both arms are entered on each trial, thus ensuring equivalent recent experience with both stimuli on the next trial. Other sources of potential interference may be within-trial interference and nonspecific sources of Pi (Cohen, Sturdy, & Hicks, 1996;Hoffman & Maki, 1986). …”

“…On the free-choice run, both goal arms are open and the reward is present in the arm opposite that on the forced choice. Alternation is a simpler version of the widely used radial maze task (Cohen, Sturdy, & Hicks, 1996). Béracochéa and Jafford (1987) showed a decline in alternation across a series of four massed trials and a rebound in accuracy on a fifth trial when the maze was altered with a cardboard insert.…”

“…Release from Pi occurs when the target stimulus, or the subject's processing of the target, is altered and recall accuracy is reinstated. Pi in animals is usually attributed to stimulus confusion in memory (e.g., Cohen, Sturdy & Hicks, 1996;D'Amato, 1973;Hoffman & Maki, 1986). Given a limited set of stimuli that vary as correct and incorrect alternatives from trial to trial, the memory of the current trial's stimulus overlaps with traces from previous trials.…”