Social facilitation in a coaction setting: An examination of the effects over learning trials

Zajonc's proposal that the presence of others facilitates emission of dominant responses was examined in a coaction setting with human maze learning. On a maze where dominant responses were likely to be correct, coacting subjects made fewer errors than those working alone. On a maze where dominant responses were likely to be incorrect, subjects performing alone made fewer errors than those coacting. Investigation of task performance at different stages in learning showed that a change in the rate of learning corresponded to a change in the dominant response from incorrect to correct. It was concluded that the presence of others has a facilitative effect on the dominant response, hindering learning when the dominant response is incorrect and helping learning when the dominant response is correct. Coaction effects were extremely pronounced in females but almost nonexistent in males.     

Food priming and short-term retention in the delayed alternation task

The delayed alternation task, with rats as subjects, was used to assess the effects of a priming food reward on subsequent retention of a reinforced target location in a T maze. Subjects received a pretrial feeding, followed by a forced-choice rewarded entry into one goal box of the maze (the “cuing” run). Following a delay interval (5–60 s), the subjects were allowed to choose either goal, with reward available only in the one not entered on the cuing run. Priming significantly reduced such alternation after 30- and 60-s delays (Experiment 1), whereas administering the reward following the cuing run had no effect on choice behavior (Experiment 2). In the third study, prefeeding had a decremental effect when the following cuing run was reinforced, but no decrement occurred when reinforcement was omitted on the cuing run. The results suggest that food reward enhances retention of spatial information, but priming reduces this effect.     

Immediate reinforcement in delayed reward learning in pigeons

Pigeons were trained on simultaneous red-green discrimination procedures with delayed reward and sequences of stimuli during the delay. In Experiment 1, three stimuli appeared during the 60-second intervals between the correct responses and reward, and the incorrect responses and nonreward. The stimulus that immediately followed a correct response also preceded nonreward, and the stimulus that followed an incorrect response preceded reward. These stimuli were 10 or .33 second in duration for different groups. Stimuli during the remainder of the delay interval differed following correct and incorrect responses. Group 10 initially persisted in the nonrewarded choice, but shifted to a preponderance of rewarded responses after further training. Group .33 rapidly acquired the correct response. Similar results were obtained in Experiment 2 where delay intervals consisted of opposite sequences of two stimuli of equal duration and total delays were 6, 20, or 60 seconds. Early in training, generalization of differential conditioned-reinforcing properties from the conditions preceding reward and nonreward to postchoice conditions had a greater effect relative to backchaining than it did later. It was concluded that delayed-reward learning is best analyzed in terms of the conditioned-reinforcing value of the patterns of cues that follow immediately after rewarded and nonrewarded responses.     

Choice As A Function Of Reinforcement Ratios In Delayed Matching-to-sample

Pigeons were studied in two experiments using a delayed matching-to-sample task. In Experiment 1, 4 subjects were exposed to a task in which the proportion of reinforcement associated with matching and nonmatching, and the overall proportion of reinforcement associated with selecting each choice, regardless of the sample stimulus, were varied. Choice was sensitive to both proportions. A least squares regression analysis showed that Wixted's (1989) proportions of reinforcement model closely fit the data from Experiment 1; however, the model failed to make accurate qualitative predictions for some test conditions. In Experiment 2, 4 subjects were exposed to a delayed matching-to-sample task in which the retention intervals and the reduction in delay to reinforcement signaled by the onset of the sample stimulus were independently varied. When the retention interval was short and when the delay-reduction value of the sample stimulus was high, the sample exerted greater control over choice; the control by the overall proportion of reinforcements for selecting each choice stimulus was correspondingly low. Conversely, when the retention interval was long and the delay-reduction value of the sample stimulus was low, the sample exerted relatively less control over choice; control by the overall proportion of reinforcements obtained for selecting each choice stimulus was correspondingly high. A signal detection analysis found that sensitivity to reinforcement varied directly with retention interval. Data were also consistent with misallocation models. No evidence was found to suggest that pigeons ignore the rate at which selecting individual choice stimuli is reinforced, as has been reported in studies with human subjects.     

Long delay learning in the T-maze

Rats were trained to go to one side of a T-maze with delays of reward lasting 1, 20, or 60 min in Expt 1 and 1 or 60 min in Expt 2. Mediation by secondary reward was prevented by administering the same delay treatment regardless of whether the response was correct or incorrect: after a response, the rat was removed from the choice alley and placed in its home cage to spend the delay. Feedback for the response was given in the startbox after the delay interval ended. The rats learned and there were no significant differences in performance among groups trained with different delays. These results had been expected on the basis of Revusky's (1971) hypothesis that removal of the rat from the learning situation to spend the delay elsewhere facilitates long delay learning by reducing associative interference. In Expt 3, this notion was tested explicitly by varying the amount of a 2-min delay to be spent in the experimental situation. Different groups of rats were left in the choice alley after the response for 0, 15, or 60 sec; then the rats were removed to spend the remainder of the 2-min delay in the home cage As predicted, the level of performance decreased as the length of time in the choice alley was increased.     

Context extinction following conditioning with delayed reward enhances subsequent instrumental responding

In Experiment 1, delayed reward generated low response rates relative to immediate reward delivered with the same frequency. Lister rats exposed to delayed reward subsequently responded at a higher rate in extinction if they received nonreinforced exposure to the conditioning context after instrumental training and prior to test, compared with animals that received home cage exposure. In Experiment 2, a signaled delay of reinforcement resulted in higher rates than an unsignaled delay. Nonreinforced exposure to the conditioning context elevated response rate for subjects in the unsignaled condition relative to a home cage group, but had no effect on response rates for subjects that had received the signaled delay. In Experiment 3, following an unsignaled reinforcement delay, groups receiving either no event or signaled food in the context responded faster in extinction than groups receiving no context exposure or unsignaled food.     

The instrumental overshadowing effect in pigeons: The role of response bursts

Experiment 1 showed that, when reinforcement is delayed by 0.5 sec for pigeons responding on a variable interval schedule, bursts of responses tend to occur during the delay interval. Such bursts are not seen when a signal (illumination of the houselight) fills the delay interval. The higher overall response rate seen with the unsignalled procedure may, therefore, be a consequence of the differential reinforcement of response bursts. Experiment 2 found, however, that the difference between the signalled and unsignalled conditions remained when the signal used was one that was relatively ineffective in suppressing bursts. Experiment 3 found that in some conditions the unsignalled procedure will generate a higher response rate than the signalled procedure even when there is no delay of reinforcement and thus little opportunity for differential reinforcement of response bursts. It is argued that, in addition to any contribution from the differential reinforcement of bursts, these effects also reflect the overshadowing of a response—reinforcer association by the signal that is a more valid predictor of the reinforcer.     

Effect of delay-interval illumination on matching behavior in the capuchin monkey

Experiment 1 demonstrated that delayed matching-to-sample in the capuchin monkey was superior when the delay interval was spent in darkness rather than in moderate illumination. In contrast with previous studies in which the delayed-matching ability of primates appeared limited to 60 sec or less, in the dark condition all subjects showed above-chance matching at a 120-sec delay interval. Experiment 2 verified that darkness during the delay interval can facilitate delayed matching and provided evidence that the effective variable was the illumination level of the delay interval rather than change in illumination, which in Exp. 1 was confounded with illumination level.     

Token reinforcement, choice, and self-control in pigeons.

Pigeons were exposed to self-control procedures that involved illumination of light-emitting diodes (LEDs) as a form of token reinforcement. In a discrete-trials arrangement, subjects chose between one and three LEDs; each LED was exchangeable for 2-s access to food during distinct posttrial exchange periods. In Experiment 1, subjects generally preferred the immediate presentation of a single LED over the delayed presentation of three LEDs, but differences in the delay to the exchange period between the two options prevented a clear assessment of the relative influence of LED delay and exchange-period delay as determinants of choice. In Experiment 2, in which delays to the exchange period from either alternative were equal in most conditions, all subjects preferred the delayed three LEDs more often than in Experiment-1. In Experiment 3, subjects preferred the option that resulted in a greater amount of food more often if the choices also produced LEDs than if they did not. In Experiment 4, preference for the delayed three LEDs was obtained when delays to the exchange period were equal, but reversed in favor of an immediate single LED when the latter choice also resulted in quicker access to exchange periods. The overall pattern of results suggests that (a) delay to the exchange period is a more critical determinant of choice than is delay to token presentation; (b) tokens may function as conditioned reinforcers, although their discriminative properties may be responsible for the self-control that occurs under token reinforcer arrangements; and (c) previously reported differences in the self-control choices of humans and pigeons may have resulted at least in part from the procedural conventions of using token reinforcers with human subjects and food reinforcers with pigeon subjects.     

Music during learning of a tactual-spatial task affects later response generalization

Equal numbers of men and women learned a finger maze, with half of the subjects initially using their right hands and the other half using their left hands. To reach criterion, subjects receiving music in the ear ipsilateral to the hand used required more trials than did those receiving no music. Furthermore, when the right hand ran the maze, music played to the ipsilateral ear also delayed learning, compared with music played contralaterally. Binaural music delayed learning when the left hand was used but not when the right hand was used. Possible causes of these effects are suggested. When subjects switched hands and relearned the maze, the number of trials to criterion depended on the group subjects were in during initial learning and not on the group they were in during the hand reversal (response generalization) trials. Although the music condition used determined the effect of music on initial learning and on response generalization, some evidence is presented that indicates that the two effects are not entirely interdependent and that they may even involve different mechanisms.     

Self-control in male and female rats

Eight male and 8 female Wistar rats were exposed to a discrete-trial procedure in which they chose between the presentation of a small (one pellet) or a large (three pellets) reinforcer. The delay to the small and large reinforcer was 6.0 s in the first condition of Experiment 1. Subjects consistently chose the large reinforcer. When the delay to the small reinforcer was decreased to 0.1 s in the next experimental condition, all subjects continued to choose the large 6.0-s delayed reinforcer. When the contingencies correlated with the two levers were reversed in the next experimental condition, the majority of subjects (5 males and 6 females) still chose the large delayed reinforcer over the small immediately presented reinforcer. The delay to the small reinforcer was maintained at 6.0 s, but the delay to the large reinforcer was varied among 9.0, 15.0, 24.0, and 36.0 s in Experiment 2, in which 4 males and 4 females participated. Most subjects consistently chose the large increasingly delayed reinforcer, although choice for the small 6.0-s delayed reinforcer developed in some females when the large reinforcer was delayed for 24.0 or 36.0 s. These choice patterns were not predicted from a literal application of a model that says choice should favor the alternative correlated with the higher (amount/delay) ratio.     

Self-control and choice in humans: Effects of video game playing as a positive reinforcer

Participants chose between reinforcement schedules differing in delay of reinforcement (interval between a choice response and onset of a video game) and/or amount of reinforcement (duration of access to the game). Experiment 1 showed that immediate reinforcement was preferred to delayed reinforcement with amount of reinforcement held constant, and a large reinforcer was preferred to a small reinforcer when both were obtainable immediately. Imposing a delay before the large reinforcer produced a preference for the immediate, small reinforcer in 40% of participants. This suggested a limited degree of “impulsivity.” In Experiment 2, unequal delays were extended by equal intervals, the amounts being kept equal. Preference for the shorter delay decreased, an effect that presumably makes possible the “preference reversal” phenomenon in studies of self-control. Overall, the results demonstrate that video game playing can produce useful, systematic data when used as a positive reinforcer for choice behavior in humans.     

Asymmetrical retention functions for sequences of light flashes or tone bursts in the rat

In Experiment 1, rats were trained in a symbolic delayed matching-to-sample task to discriminate sample stimuli that consisted of sequences of magazine light flashes. The intertrial interval was illuminated by the houselight for Group Light, and it was dark for Group Dark. Retention functions exhibited a choose-many response bias when the delay interval was illuminated by the houselight in both groups, and no consistent response bias when the delay interval was dark. In Experiment 2, rats were trained to discriminate sample stimuli that consisted of sequences of tone bursts. During delay testing, a different tone (i.e., different frequency and location than the sample tone) was present or absent during the delay interval. The retention functions exhibited a significant choose-many bias when tone was present during the delay and a choose-few bias when tone was absent. Asymmetrical retention functions for tone burst and light flash sequences are due to the similarity between the stimulus conditions of the delay interval and the modality of the sequential event being discriminated. These results are consistent with an instructional ambiguity explanation of response biases in memory for number.     

Three kinds of error-signalling responses in a serial choice task

During serial self-paced choice response tasks mean reaction times (RTs) for responses which are made in order to correct errors are faster than mean RTs for other correct responses. Experiment I showed that subjects can accurately correct errors in a four-choice task by making the response which they should have made, even though they are given no indication that an error has occurred. Experiment 2 showed that subjects correct their errors faster and more accurately when they use correction procedure than when they make a common response to all errors. The implication that subjects can correct errors because they know what response they should have made allows some comments on the constraints which must be met by various models which have been proposed to explain error-correction.     

An investigation of the differential-outcomes effect within sessions

The differential-outcomes effect is manifest as more accurate performance of a delayed conditional discrimination when alternative choice responses are followed by different reinforcers than when they are followed by the same reinforcer. In Experiment 1, a differential-outcomes effect was demonstrated within sessions by signaling the duration of food access for correct responses with stimuli appearing in conjunction with the sample stimuli. The delayed matching-to-sample performance of 5 pigeons was more accurate when green choice responses (matching a green sample) were followed by 3.5-s food access and red choice responses (matching a red sample) were followed by 0.5-s food access (different-outcome trials) than when the correct choice responses were both followed by 1.5-s reinforcers (same-outcome trials). In Experiment 2, the acquisition of this differential-outcomes effect was characterized by a progressive decrease in rate of forgetting on different-outcome trials and no change in rate of forgetting on same-outcome trials. In addition, accuracy at the shortest delay intervals for both different-outcome and same-outcome trials increased over acquisition, but to a greater extent for different-outcome trials. These data suggest that both memorial and attentional (time-dependent and time-independent) factors contribute to the differential-outcomes effect.     

Choice, foraging, and reinforcer duration.

Pigeons were exposed to a foraging schedule characterized by three different states, beginning with a search state in which completion of a variable interval on a white key led to a choice state. In the choice state the subject could, by appropriate responding on a fixed ratio of three, either accept or reject the schedule offered. If the subject accepted the schedule, it entered a handling state in which the appropriate reinforcer amount was presented according to a variable-interval schedule. In Experiment 1 the shorter duration reinforcer was more likely to be accepted the longer the duration of the search state and the shorter the equal durations of the handling states. In Experiment 2 the shorter duration reinforcer was more likely to be accepted the longer the handling time preceding the longer duration reinforcer. All of the results were in qualitative--and some were in quantitative--agreement with those predicted by the delay-reduction hypothesis and the optimal-diet model.     

Implicit motor sequence learning is not purely perceptual

Many reports have indicated that implicit learning of sequences in a choice response time task is primarily perceptual; subjects learn the sequence of stimuli rather than the sequence of motor responses. Three experiments tested whether implicit motor sequence learning could be purely perceptual: no support was found for that hypothesis. Subjects who merely watched stimuli did not learn the sequence implicitly (Experiment 1), and sequence learning transferred robustly to a different set of stimulus cues (Experiment 2). In the final experiment, the stimulus-response mapping was changed at transfer so that one group of subjects pushed the same sequence of keys but saw new stimuli, whereas another group pushed a different sequence of keys but saw the same stimuli. Transfer to the new mapping was shown only if the motor sequence was kept constant, not the perceptual sequence. It is proposed that subjects learn a sequence of response locations in this and similar tasks.     

Context specificity of conditioned-reinforcement effects on discrimination acquisition

Pigeons were trained on a series of reversals of a simultaneous form discrimination in which the trial outcomes were separated from the choice responses by an 8-s delay interval. Different conditions were defined by the stimuli occurring during the two halves of the delay interval. Discrimination learning was greatly facilitated by having differential stimuli during the delay following correct versus incorrect choices. When the differential stimuli appeared only at the midpoint of the delay, some facilitation occurred relative to when no different stimuli occurred, but there was substantially less facilitation than when the differential stimuli occurred immediately contingent on choice. A reversed-stimulus condition, in which the stimulus at the onset of the delay following a correct choice was the same as that during the last segment of the delay following an incorrect choice, and the stimulus at the onset of the delay following an incorrect choice was the same as that preceding food during the last segment of the delay following a correct choice, also facilitated discrimination learning relative to the nondifferential stimulus conditions.     

The role of marking when reward is delayed

Two-choice spatial discrimination by rats is enhanced if a salient stimulus marker occurs immediately after every choice response and again after a delay interval (Lieberman, McIntosh & Thomas, 1979). Three experiments further explore this effect. Experiment 1 found that the second marker is unnecessary. Experiment 2 found that a marker presented before a response is as effective as one presented after. Both effects could be explained in terms of markers focusing attention on subsequent cues. Experiment 3, however, found that markers after choice enhance learning even when no discriminative cues are present following the marker. Markers thus appear to initiate both a backward search through memory and attention to subsequent events; both processes help to identify events that might be related to the unexpected marking stimulus.     

When people’s judgments of learning (JOLs) are extremely accurate at predicting subsequent recall: the “Displaced-JOL effect”

Judgments of learning (JOL) made after a delay more accurately predict subsequent recall than JOLs made immediately after learning. One explanation is that delayed JOLs involve retrieving information about the target item from secondary memory, whereas immediate JOLs involve retrieval from primary memory. One view of working memory claims that information in primary memory is displaced to secondary memory when attention is shifted to a secondary task. Thus, immediate JOLs might be as accurate as delayed JOLs if an intervening task displaces the target item from primary memory, requiring retrieval from secondary memory, prior to making the JOL. In four experiments, participants saw related word-pairs and made JOLs predicting later recall of the item. In Experiment 1, delayed JOLs were more accurate than JOLs made shortly after learning, regardless of whether a secondary task intervened between learning and JOL. In Experiments 2–4, the secondary task demands increased and JOLs made shortly after learning with an intervening task were just as accurate as delayed JOLs, and both were more accurate than immediate JOLs with no intervening task (Experiment 4). These results are consistent with a retrieval-based account of JOLs, and demonstrate that the “delayed-JOL effect” can be obtained without a long delay.