On two effects of signaling the consequences for remembering

Abstract

Five pigeons were trained to perform a delayed matching-to-sample task in which red-and greencolored keys were presented as sample and choice stimuli, and the duration of a delay interval varied across trials. Experiment 1 investigated the effects on delayed-matching accuracy of signaling different durations offood access for the two correct responses (the differential-outcomes effect), and of signaling nondifferential but larger durations for both responses (the signaled-magnitudes effect). In Condition 1, a vertical bar on either sample signaled different rewards (or different outcomes, DOs) for correct red and correct green responses (0.5 and 3.5 sec, respectively), and a horizontal bar signaled equal durations of food access (or same outcomes, SOs) for these responses (1.5 sec). In Condition 2, the horizontal bar signaled equally large rewards for the two correct responses (3.5 sec), and the vertical bar signaled equally small rewards (0.5 sec). Delayed-matching accuracies were higher on DO trials than on SO trials, and they were higher on large-reward trials than on smallreward trials. However, analyses of discriminability estimates as a function of delay-interval duration revealed differences between the forgetting functions reflecting these two effects. Signaling DOs increased the initial level of the function and reduced its slope relative to signaling SOs, whereas signaling larger rewards increased the initial level of the function but did not affect its slope relative to signaling smaller rewards. Experiment 2 investigated whether the difference between the initial levels of DO and SO functions in Condition 1 resulted from overall longer food access on the former trials. However, varying the food-access times on SO trials across three conditions (0.5, 3.5, and 1.5 sec) failed to produce systematic effects consistent with this hypothesis. The results are discussed with respect to the mechanisms that could be responsible for the two effects.

Remembering: The role of extraneous reinforcement

“…A similar effect on the forgetting function is generated by the differential outcomes effect. When different qualities or durations of food are provided for correct B 1 and B 2 responses, initial discriminability is higher, and forgetting is less rapid (Brodigan & Peterson, 1976;Jones & White, 1994;Jones, White, & Alsop, 1995). This result is consistent with a general improvement in performance (time independent), coupled with a modification of disruptive behaviors that occur during the retention interval (time dependent; Jones & White, 1994;Trapold, 1970).…”

“…Their overall short versus long duration, however, is signaled by external stimuli. The result is that initial discriminability is higher when longer reinforcers are signaled, with no change in the rate of forgetting (Brown & White, 2005;Jones et al, 1995;McCarthy & Voss, 1995;Nevin & Grosch, 1990). A similar signaled probability effect was reported by Brown and White.…”

Psychophysics of Remembering

“…The two types of trials are differentially signaled. The result was confirmed by McCarthy and Voss (1995) and Jones, White, and Alsop (1995). Our generalization of the result is that accuracy may be overall higher when higher absolute rates of reinforcement are arranged in delayed matching to sample.…”

Behavioral and associative effects of differential outcomes in discrimination learning

“…These effects are representative of a literature in which nearly 25 variations of differential outcomes have been used in tasks ranging from simple two-choice and go/no-go successive discriminations (e.g., Blundell et al, 2001;Carlson & Wielkiewicz, 1972;Fedorchak & Bolles, 1986;Friedman & Carlson, 1973;Morgan & Baker, 1997;Papini & Silingardi, 1989;Urcuioli & Zentall, 1992) to more complex feature-ambiguous discriminations (Nakajima & Kobayashi, 2000) and identity and symbolic matching-to-sample (e.g., Alling, Nickel, & Poling, 1991a, 1991bJones, White, & Alsop, 1995;Saunders & Sailor, 1979;Urcuioli & DeMarse, 1996;Zentall & Sherburne, 1994). Although not always evident in the acquisition of discriminative performance (e.g., Brodigan & Peterson, 1976;Edwards et al, 1982;Goodwin & Baker, 2002;Savage, Pitkin, & Careri 1999), the effect almost always materializes when a retention interval intervenes between S and R (i.e., in working memory).…”

“…This acquired distinctiveness explanation makes no appeal to an additional cue but, instead, postulates the potentiation of stimulus control by the nominal stimuli when they signal different outcomes. Jones et al (1995) evaluated this alternative in pigeons' delayed matching-to-sample by arranging that two hue sample stimuli signaled different reward magnitudes for correct choice on some matching trials but the same (constant) reward magnitude on other trials. Two derived measures were used to compare performances under these two conditions: log d 0 , sample discriminability with no retention interval, and b, the rate of forgetting with increasing retention intervals.…”