Pigeons’ short-term memory for temporal and visual stimuli in delayed matching-to-sample

Abstract

In the present experiment, we compared directly pigeons' short-term memory of temporal and visual stimuli in a delayed matching-to-sample task. The sample stimuli consisted of red and green lights presented for 5 and 30 sec, followedby a retention interval and blue and yellow comparisons. For subjects in the visual group, duration was irrelevant and the color of the sample was the conditional cue. For animals in the temporal group, color was irrelevant and duration of the sample was the conditional stimulus. The results showed that acquisition of the matching task was faster and accuracy was higher in the visual than in the temporal group. More importantly, memory of either sample generally declined at a similar rate when the duration of the retention interval was increased and when the intertrial interval was reduced. Taken together, the results indicate that with 1-8·sec retention intervals, short-term memory for temporal stimuli is similar to that found with color-visual samples. The findings are discussed in terms of'retrospective and prospective processing.Over the past decade or so, the research examining pigeons' short-term memory (STM) has been extensive (e.g., Cook, 1980;Honig, 1978; Kendrick & Rilling, 1984; Kendrick, Rilling, & Denny, 1986;Roberts & Grant, 1974, 1976Roitblat, 1980;Roitblat, Bever, & Terrace, 1984). Many of these studies employed the delayed matching-to-sample (DMTS) procedure. In DMTS, the subject is presented with a sample stimulus to which it responds. After the sample is terminated, a retention interval (RI) occurs, followed by a choice between two comparison stimuli, one of which matches or is identical to the previous sample. Responses to the matching comparison are reinforced and responses to the nonmatching comparison are not reinforced.Recently, much experimental attention has focused on the content of STM. The basic question is whether subjects retain attributes of the sample during the RI (retrospective processing), or whether they retain an instructional code regarding the to-be-chosen comparison (prospective processing) (see Honig & Thompson, 1982;Roitblat, 1980;Stonebraker, 1981;Wasserman, 1986, for further discussion). Kraemer and Roberts (1984) indirectly examined retrospective and prospective processing by This paper represents a portion of the first author's dissertation presented to Colorado State University in partial fulfillment of the PhD requirement. Some of this work was presented at the 1986 meeting of the Rocky Mountain Psychological Association, Denver, CO. The authors would like to thank: Marcia Spetch and the anonymous editors for their thoughtful comments, which improved the quality of the paper. Correspondence may be addressed to Robin L. Bowers, Department of Psychology, Augustana College, Rock Island, IL 61201. 23training pigeons on a symbolic DMTS task in which visual or auditory samples were associated with visual comparisons. For some pigeons, the sample stimuli were 3000-and 300-Hz tones, and these were associated with yellow and blue, respectively...

Memory codes for temporal and nontemporal samples in many-to-one matching by pigeons

“…Bowers and Richards (1990) obtained a similar result in an experiment in which pigeons were presented with 5-or 30-sec durations of a red or green sample. For one group of birds, the color of the sample was the relevant cue; for the other group, the duration of the sample was the relevant cue.…”

Analogical and nonanalogical coding of samples differing in duration in a choice-matching task in pigeons.

“…Recently, Bowers and Richards (1990) conducted a delay test using pigeons that had been trained in a procedure similar to that used in the consistent group described earlier.…”

“…However, Spetch and Wilkie (1982) obtained a choose-short effect at longer delays in pigeons trained in an MTO procedure involving consistent mapping, suggesting that their pigeons coded the samples analogically. Spetch and Wilkie (1982) used food access and light as carriers rather than houselight and keylight as in our Experiment 3 or red and green keylights as in Bowers and Richards's (1990) experiment. This fact may be important, because duration discrimination is acquired considerably more quickly on trials in which the carrier for duration is food than on trials in which the carrier is houselight (see Spetch & Wilkie, 1981).…”

“…Recently, Bowers and Richards (1990) conducted a delay test using pigeons that had been trained in a procedure similar to that used in the consistent group described earlier. As in the present study, no evidence of a choose-short effect was obtained, a result Bowers and Richards interpreted as reflecting prospective coding.…”

“…Spetch and Wilkie (1982) used food access and light as carriers rather than houselight and keylight as in our Experiment 3 or red and green keylights as in Bowers and Richards’s (1990) experiment. This fact may be important, because duration discrimination is acquired considerably more quickly on trials in which the carrier for duration is food than on trials in which the carrier is houselight (see Spetch & Wilkie, 1981).…”