Interference of delayed matching to sample in pigeons: Effects of interpolation at different periods within a trial and stimulus similarity

Abstract

Delayed matching-to-sample performance by pigeons was interfered with by displaying a monochromatic annulus around the center (sample) pecking key. The wavelength of the annulus and its point of interpolation within a trial were varied to determine possible differential effects on matching accuracy. Experiment 1 showed that delayed matching was most disrupted when the interference stimulus (570 nm, 630 DID, or achromatic white) appeared during the delay interval of a trial. Little if any disruption occurred when the interference stimulus was present during the sample and choice periods. The spectral relationship between the chromatic interference stimuli (570 and 630 nm) and the sample stimuli (570 and 630 nm) did not consistently influence the degree to which matching accuracy was affected in any interpolation condition. Experiment 2 found a similar pattern of within-trial effects when the interference stimulus was simply a change from a white achromatic annulus to a chromatic one. This finding indicates that illumination changes, such as the popular houselight variation, are not necessary to produce interference in delayed matching to sample. Even with illumination held constant, however, performance was not differentially sensitive to the similarity between interference and sample stimulus wavelengths. It is suggested that other experiments showing similarity effects in interference of delayed matching to sample were conducted in such a way that subjects confused the interfering stimuli with the samples. 595

Pigeons' Spatial Memory: Iii. Effect of Distractors on Delayed Matching of Key Location

“…The general ineffectiveness of presenting a houselight distractor during sample and comparison phases of the trial replicated results reported previously by Wright et al (1981) and was not unexpected. However, the finding that the delay-interval houselight presentation did not generally affect delayed-matching accuracy was apparently unique in the literature and accordingly was subjected to a more detailed analysis.…”

“…Further, it is often assumed that such effects mirror what happens during regular, uninterrupted trials (cf. Wright et al, 1981). Accordingly, when an animal makes an error on a baseline trial, it is assumed that some uncontrolled stimulus appeared during the delay interval and disrupted remembering.…”

“…Such a manipulation has been found previously to affect adversely DMTS accuracy in a wide variety of situations and in several species (e.g., Cook, 1980;D'Amato & O'Neill, 1971;Maki, Moe, & Bierley, 1977;Wilkie et al, 1981). In addition to interpolating houselight illumination during the delay interval, we, like Wright, Urcuioli, Sands, and Santiago (1981), also assessed the effects of illuminating the houselight during sample presentation and choice phases of the matching trials.…”

The role of interpolated stimuli in the retroactive interference of pigeon short-term memory

“…Similarity of the interpolated stimuli to the sample and test stimuli, and saliency, familiarity, and complexity of the interpolated stimuli are not significant sources of retroactive interference (Grant & Roberts, 1976;Medin et al, 1980;Wright et al, 1981). Both ambient illumination and localized keylight illumination interpolated into the delay interval of delayed matching interfere with matching accuracy (Grant & Roberts, 1976).…”

“…Retroactive interference is observed when matching accuracy on the interpolated test trials declines relative to matching accuracy on the baseline trials (Grant & Roberts, 1976;Medin, Reynolds, & Parkinson, 1980;Moise, 1970;Wright, Urcuioli, Sands, & Santiago, 1981).…”