Doolan, K. E., & Bizo, L. A. (2013). Reinforced behavioral variability in humans. Psychological Record, 63, 725-734 (original) (raw)
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ReinfoRced BehavioRal vaRiaBility in humans
This study aimed to assess the role of reinforced behavioral variability in the learning of a 6-digit target sequence (211212) with 3 groups of human participants (n = 39). For the first group (Control), only the target sequence was reinforced. For the second group (Any), the target sequence was reinforced, and any sequence other than the target sequence could be reinforced on a variable interval 60-s schedule. For the third group (Variable), the target sequence was reinforced, and any sequence other than the target sequence could be reinforced on a variable interval 60-s schedule, if it met a variability criterion. The Control group produced the target sequence significantly more often than the Variable group by the end of the experimental sessions. These findings contradict previous studies with rats that have shown that reinforcement of behavioral variability facilitates the learning of difficult response sequences but are consistent with results from previous studies with humans. Potential reasons for this disparity are discussed.
Reinforced variability decreases with approach to reinforcers
Journal of Experimental Psychology: Animal Behavior Processes, 1996
Anticipation of rewards had different effects on operant variability than on operant repetition. We reinforced variable (VAR) response sequences in groups of rats and pigeons and repetitive (REP) response sequences in separate groups. A fixed number of variations or repetitions was required per food reinforcer (e.g., fixed-ratio 4). Although VAR contingencies resulted in high levels of variability and REP contingencies in high repetition, opposite patterns of performance accuracy were observed as rewards were approached. Likelihood of satisfying REP contingencies increased within the fixed ratio, whereas likelihood of satisfying VAR contingencies decreased. These opposite patterns of accuracy were also generated by conditioned reinforcing stimuli correlated with food. Constraints on variability by proximity to reinforcers may explain some detrimental effects of reward.
Behavioral variability is controlled by discriminative stimuli
Animal Learning & Behavior, 1998
Previous research has demonstrated that behavioral variability can be modified by reinforcers contingent on it, but there has been no convincing evidence of discriminative stimulus control over such variability. We therefore rewarded 20 rats for variable response sequences in the presence of one stimulus and provided equal rewards independently of sequence variability in the presence of a second stimulus. We found that sequence variability was significantly higher during the first stimulus than during the second, with the greatest difference occurring immediately following onset of the stimuli. Removing the discriminative stimuli caused levels of variability to converge. These experiments provide strong evidence that behavioral variability can be controlled by discriminative stimuli, which may be important for general theories of operant behavior and their applications.
Learning & Behavior, 2012
The goal of the present study was to evaluate the role of verbal stimuli in the production of response variability in humans. College students were distributed into three groups and asked to type three-digit sequences. Participants in the systematic group were instructed to produce sequences according to a rule of their choice; those in the random group were instructed to produce sequences according to chance; and those in the control group were not instructed about how to produce sequences. The experiment employed an ABA design. During the A phases, low-frequent sequences were reinforced (variability contingency), whereas during the B phase, reinforcement was withdrawn (extinction). The results indicated the following: (1) The instructions were efficient at producing systematic and random-like patterns for the systematic and random groups, respectively; in the absence of instructions, a mix of both patterns was observed. (2) Behavior was sensitive to extinction independently of the instructions provided. (3) Systematic patterns favored a more equiprobable distribution of sequences across trials. (4) Reaction times were longer for responding in a systematic than in a random-like fashion. The present findings suggest that individual differences in meeting variability contingencies may be due, at least partially, to instructional control.
The Effects of Delayed Reinforcement on Variability and Repetition of Response Sequences
Journal of the Experimental Analysis of Behavior, 2006
Four experiments examined the effects of delays to reinforcement on key peck sequences of pigeons maintained under multiple schedules of contingencies that produced variable or repetitive behavior. In Experiments 1, 2, and 4, in the repeat component only the sequence right-right-left-left earned food, and in the vary component four-response sequences different from the previous 10 earned food. Experiments 1 and 2 examined the effects of nonresetting and resetting delays to reinforcement, respectively. In Experiment 3, in the repeat component sequences had to be the same as one of the previous three, whereas in the vary component sequences had to be different from each of the previous three for food. Experiment 4 compared postreinforcer delays to prereinforcement delays. With immediate reinforcement sequences occurred at a similar rate in the two components, but were less variable in the repeat component. Delays to reinforcement decreased the rate of sequences similarly in both components, but affected variability differently. Variability increased in the repeat component, but was unaffected in the vary component. These effects occurred regardless of the manner in which the delay to reinforcement was programmed or the contingency used to generate repetitive behavior. Furthermore, the effects were unique to prereinforcement delays.
Behavioral Variability as Avoidance Behavior
Journal of the Experimental Analysis of Behavior, 2017
Link para download: http://onlinelibrary.wiley.com/doi/10.1002/jeab.293/full This study aimed to investigate whether variable patterns of responses can be acquired and maintained by negative reinforcement under an avoidance contingency. Six male Wistar rats were exposed to sessions in which behavioral variability was reinforced according to a Lag contingency: Sequences of three responses on two levers had to differ from one, two or three previous sequences for shocks to be avoided (Lag 1, Lag 2 and Lag 3, respectively). Performance under the Lag conditions was compared with performance on a Yoke condition in which the animals received the same reinforcement frequency and distribution as in the Lag condition but behavioral variability was not required. The results showed that most of the subjects varied their sequences under the Lag contingencies, avoiding shocks with relatively high probability (≥ 0.7). Under the Yoke procedure, responding continued to occur with high probability, but the behavioral variability decreased. These results suggest that behavioral variability can be negatively reinforced.
Reinforced Variability in Animals and People Implications for Adaptive Action
Although reinforcement often leads to repetitive, even stereotyped responding, that is not a necessary outcome. When it depends on variations, reinforcement results in responding that is diverse, novel, indeed unpredictable, with distributions sometimes approaching those of a random process. This article reviews evidence for the powerful and precise control by reinforcement over behavioral variability, evidence obtained from human and animal-model studies, and implications of such control. For example, reinforcement of variability facilitates learning of complex new responses, aids problem solving, and may contribute to creativity. Depression and autism are characterized by abnormally repetitive behaviors, but individuals afflicted with such psychopathologies can learn to vary their behaviors when reinforced for so doing. And reinforced variability may help to solve a basic puzzle concerning the nature of voluntary action.
Resistance to change and preference for variable versus fixed response sequences
2012
In Experiment 1, 4 pigeons were trained on a multiple chain schedule in which the initial link was a variable-interval (VI) 20-s schedule signalled by a red or green center key, and terminal links required four responses made to the left (L) and/or right (R) keys. In the REPEAT component, signalled by red keylights, only LRLR terminal-link response sequences were reinforced, while in the VARY component, signalled by green keylights, terminal-link response sequences were reinforced if they satisfied a variability criterion. The reinforcer rate for both components was equated by adjusting the reinforcer probability for correct REPEAT sequences across sessions. Results showed that initial-and terminal-link responding in the VARY component was generally more resistant to prefeeding, extinction, and response-independent food than responding in the REPEAT component. In Experiment 2, the REPEAT and VARY contingencies were arranged as terminal links of a concurrent chain and the relative reinforcer rate was manipulated across conditions. For all pigeons, initial-link response allocation was biased toward the alternative associated with the VARY terminal link. These results replicate previous reports that operant variation is more resistant to change than operant repetition (Doughty & Lattal, 2001), and show that variation is preferred to repetition with reinforcer-related variables controlled. Behavioral momentum theory (Nevin & Grace, 2000) predicts the covariation of preference and resistance to change in Experiments 1 and 2, but does not explain why these aspects of behavior should depend on contingencies that require repetition or variation.