Intrinsic reinforcing properties of putatively neutral stimuli in an instrumental two-lever discrimination task     

Phil Reed  Chris Mitchell  Tristan Nokes 《Learning & behavior》1996,24(1):38-45

Four experiments examined the influence of a stimulus presented after one response in a two-lever choice task. In Experiment 1, food-deprived rats trained on a concurrent variable-interval extinction schedule responded more often on the extinction lever when such responding periodically produced a visual stimulus than when it did not. In Experiments 2 and 3, a similar signal-induced enhancement effect was found even when food was delivered randomly with respect to responding on both levers or when no food was presented. In Experiment 4, a response-contingent visual stimulus elevated responding to the lever on which it was presented, but an auditory cue suppressed responding. These findings indicate that visual stimuli may possess intrinsically reinforcing properties for rats.  相似文献   

Microanalysis of variable-interval performance during stimulus compounding     

M. Catherine Bushnell  Stanley J. Weiss 《Learning & behavior》1978,6(1):66-71

Additive summation is observed when more responses are emitted to the simultaneous presentation (tone-plus-light) of independently conditioned stimuli (tone and light) than to either stimulus presented alone. The current experiment sought to determine if this increased rate during tone-plus-light was a function of a new modal interresponse time (IRT) or a differential mixing of pauses with a modal IRT characteristic of the responding in tone and light alone. Three rats were trained on a three-component multiple schedule where tone and light were each associated with a variable-interval 30-sec schedule while a variable-interval 100-sec operated in the simultaneous absence of these stimuli, tone-off and light-out. Baseline response rates were 2–4 times as high in tone or light as in their absence. In testing, more responses were emitted to tone-plus-light than to tone or light by all animals, but the modal IRT was in the 0.2–0.4-sec IRT bin for all test conditions. Tone-plus-light controlled fewer long IRT values and more responses in the short modal category than tone or light alone. These results support the response mixing hypothesis of stimulus control; i.e., no “new” behavior was observed during the novel combination of stimulus elements, only a mixture of previously reinforced behavior patterns in different proportions.  相似文献   

The influence of context-reinforcer associations on instrumental performance     

John M. Pearce  Geoffrey Hall 《Learning & behavior》1979,7(4):504-508

In each of two experiments, rats were trained to press the lever in a Skinner box, food reinforcement being available on a variable-interval 60-sec schedule (VI 60). There followed an “exposure phase” for which the levers were removed from the boxes, and then a final test with the levers replaced to assess the effects of the intervening treatment on instrumental responding. Experiment 1 showed that simple exposure to the box reduced the vigor of instrumental performance in comparison with a condition in which food was made available during the exposure phase. Animals which received no exposure treatment also showed a relatively high rate of response. Experiment 2 demonstrated that an exposure treatment in which the occurrence of food is signaled by a light stimulus also leads to a decline in instrumental responding. These results are held to support the notion that associations between the context and the reinforcer serve to energize appetitive instrumental behavior.  相似文献   

Inhibitory control by one stimulus after an increase in the frequency of reinforcement associated with another stimulus     

Ralph W. Richards 《Learning & behavior》1978,6(3):286-289

Pigeons were trained on a multiple variable-interval 5-min variable-interval 5-min schedule and then shifted to either a multiple variable-interval 1-min variable-interval 5-min or a multiple variable-interval 30-sec variable-interval 5-min schedule. A generalization test was subsequently administered along the dimension containing the stimulus associated with the variable-interval 5-min component. The generalization gradients for subjects that received multiple variable-interval 1-min variable-interval 5-min training were not consistent in shape. However, an incremental gradient was obtained from each subject that received multiple variable-interval 30-sec variable-interval 5-min training. Thus, a sufficiently large reduction in merely the relative frequency of reinforcement during a stimulus resulted in that stimulus’ acquiring inhibitory control over responding.  相似文献   

Response–food delay gradients for lever pressing and schedule-induced licking in rats     

Ricardo Pellón  Ángeles Pérez-Padilla 《Learning & behavior》2013,41(2):218-227

Eight food-deprived Wistar rats developed stable patterns of lever pressing and licking when exposed to a fixed-time 30-s schedule of food pellet presentation. The rats were trained to lever press by presenting the lever 10 s before the programmed food delivery, with the food pellet being delivered immediately upon a lever press. The operant contingency was then removed and the lever was inserted through the entire interfood interval, being withdrawn with food delivery and reinserted 2 s later. On successive phases of the study, a protective contingency postponed food delivery if responses (lever presses or licks) occurred within the last 1, 2, 5, 10, 20, or 25 s of the interfood interval. Lever pressing was reduced at much shorter response–food delays than those that reduced licking. These results demonstrate that reinforcement contributes to the maintenance of different response patterns on periodic schedules, and that different responses are differentially sensitive to delays.  相似文献   

Omission training and positive conditioned suppression in the rat     

C. M. Locurto  John Tierney  Stephen Fitzgerald 《Learning & behavior》1981,9(2):261-268

Suppression of operant responding during a conditioned stimulus (CS) was studied in two procedures. In both procedures, operant leverpressing was maintained by a variable-interval 1-min food-delivery schedule, and insertion of a second lever served as the CS. In the first procedure, autoshaping, food followed each CS presentation irrespective of a subject’s behavior during the CS. In the second procedure, omission training, contact with the CS canceled the delivery of food scheduled for the end of that CS. In the first experiment, subjects were exposed to omission training followed by autoshaping; these procedures were reversed in the second experiment. In each experiment, the omission contingency resulted in fewer CS contacts and less suppression of operant responding during the CS than did autoshaping. These differences were more notable in subjects receiving the sequence autoshaping→omission training (Experiment 2). Direct observations in Experiment 2 revealed that, for subjects that were contacting the CS frequently when the omission contingency was introduced, reductions in signal contacts were accompanied by redistributions of behavior. The form of these redistributions depended upon behavior allocation at the time the omission contingency was imposed.  相似文献   

Blocking in autoshaped lever-pressing procedures with rats     

Peter C. Holland  Judith S. A. Asem  Connor P. Galvin  Caitlin Hepps Keeney  Melanie Hsu  Alexandra Miller  Vivian Zhou 《Learning & behavior》2014,42(1):1-21

Rats will approach and contact a lever whose insertion into the chamber signals response-independent food delivery. This “autoshaping” or “sign-tracking” phenomenon has recently attracted considerable attention as a platform for studying individual differences in impulsivity, drug sensitization, and other traits associated with vulnerability to drug addiction. Here, we examined two basic stimulus selection phenomena—blocking and overshadowing—in the autoshaped lever pressing of rats. Blocking and overshadowing were decidedly asymmetrical. Previously reinforced lever-extension conditioned stimuli (CSs) completely blocked conditioning to auditory cues (Exps. 1 and 2), and previously nonreinforced lever-extension CSs overshadowed conditioning to auditory cues. By contrast, conditioning to lever-extension CSs was not blocked by either auditory (Exp. 3) or lever-insertion (Exp. 4) cues, and was not overshadowed by auditory cues. Conditioning to a lever-insertion cue was somewhat overshadowed by the presence of another lever, especially in terms of food cup behavior displayed after lever withdrawal. We discuss several frameworks in which the apparent immunity of autoshaped lever pressing to blocking might be understood. Given evidence that different brain systems are engaged when different kinds of cues are paired with food delivery, it is worth considering the possibility that interactions among them in learning and performance may follow different rules. In particular, it is intriguing to speculate that the roles of simple cue–reinforcer contiguity, as well as of individual and aggregate reinforcer prediction errors, may differ across stimulus classes.  相似文献   

Effects of food primes on the operant behavior of nondeprived rats     

Leonard A. Eiserer 《Learning & behavior》1978,6(3):308-312

After rats had been trained to press a lever for food reward, experimenter-initiated food “primes” increased the likelihood of subsequent responding during periods in which the subjects were nondeprived. No such priming effects were found after presentation of a stimulus that had previously been paired with food. In other experiments, nonreinforced leverpresses, as well as subthreshold components of the leverpress response (e.g., forepaw raising), were also found to be enhanced by food primes. Taken together with other reports in the literature, the present findings are consistent with a “motivational aftereffects” interpretation of priming, and also with the notion that all stimuli which possess reinforcing properties possess priming properties as well.  相似文献   

In a daily time–place learning task,time is only used as a discriminative stimulus if each daily session is associated with a distinct spatial location     

Scott H. Deibel  Matthew L. Ingram  Andrew B. Lehr  Hiliary C. Martin  Darlene M. Skinner  Gerard M. Martin  Isaac M. W. Hughes  Christina M. Thorpe 《Learning & behavior》2014,42(3):246-255

It is difficult for rats to acquire daily time–place (TP) learning tasks. One theory suggests that rats do not use time of day as a stimulus signaling a specific response. In the present study, we tested rats’ ability to use time of day as a discriminative stimulus. A fixed-interval procedure was used in which one lever provided reinforcement on a FI-5-s schedule in morning sessions, and the same lever provided reinforcement on a FI-30-s schedule in afternoon sessions. Because only one place was used in this paradigm, the rats could only use time of day to acquire the task. Mean responses during the first 5 s of the first trial in each session indicated that the rats did not discriminate between the two sessions. In Phase II, a different lever location was used for each of the two daily sessions, which meant that both spatial and temporal information could be used to acquire the task. The rats readily acquired the task in this phase, and probe trials indicated that the rats were using a combination of spatial and temporal information to discriminate between the two different trial types. When the spatial cue was removed in Phase III, rats no longer discriminated the two sessions, suggesting that time can only be used as a discriminative stimulus when each daily session is associated with a distinct spatial location.  相似文献   

Generalization of fixed-interval response patterning in pigeons     

Thomas D. Nelson  G. William Farthing 《Learning & behavior》1973,1(3):183-188

Three pigeons were trained on a multiple schedule in which keypecking was reinforced on a fixed-interval (FI) schedule in the presence of a vertical line and on a variable-interval (VI) schedule in the presence of a horizontal line. Response rates in the former component were positively accelerated (the “FI scallop”), whereas response rates in the second component were relatively constant. In a subsequent generalization test on the line-tilt continuum, the index of curvature decreased systematically as the line was rotated from vertical to horizontal in 30-deg steps. Frequency distributions of indices of curvature suggested that intermediate average index values for intermediate generalization test stimuli were mainly the result of intermediate response patterns in the individual test stimulus presentation, rather than the averaging of VI-like patterns during some stimulus presentations with FI-like patterns during other stimulus presentations.  相似文献   

Preference between fixed-interval and variable-interval schedules of reinforcement: Separate roles of temporal scaling and predictability     

Paul W. Frankel  Walter Vom Saal 《Learning & behavior》1976,4(1):71-76

Pigeons’ preference between fixed-interval and variable-interval schedules was examined using a concurrent-chains procedure. Responses to two concurrently available keys in the initial links of the concurrent chains occasionally produced terminal links where further responses were reinforced under either a fixed- or variable-interval schedule. In previous studies, preferences for the variable schedule with such a procedure have been interpreted as reflecting atemporal scaling process that heavily weights the shorter intervals in the variable schedule. The present experiment examined whetherpredictability, i.e., the presence of external stimuli correlated with the reinforcement interval, might also influence preference in such situations. When the two intervals in a variable schedule were made predictable by being associated with different key colors, preference for that schedule increased. This increase was reliable but small in magnitude and transient when initial-link responses only occasionally produced terminal links; it was large in magnitude when only one response in the initial link was required to produce the appropriate terminal-link schedule. The results suggest that preference between fixed and variable schedules may be influenced both by temporal scaling and to a lesser extent by predictability of the reinforcement intervals.  相似文献   

Applying Konorski’s model of classical conditioning to signal-centered behavior in the rat: Some functional similarities between hunger CRs and sign-tracking     

Graham C. L. Davey  Gary G. Cleland  David A. Oakley 《Learning & behavior》1982,10(2):257-262

Two experiments were conducted to investigate functional similarities between “hunger CRs” of Konorski’s (1967) model of appetitive classical conditioning and sign-tracking behavior in rats. Konorski’s model predicts that hunger CRs will be facilitated (1) when a nonrein-forced stimulus similar to the reinforced CS is introduced, and (2) when some CS presentations are unexpectedly nonreinforced. In Experiment 1, hungry rats acquired a leverpress response to a retractable lever that was paired with response-independent food. Following this training, a second lever was introduced whose presentation was not followed by food. The effect of the presence of this second lever was to facilitate responding to the original lever. In Experiment 2, single-lever autoshaping training was followed by a shift from 100% pairing of the lever with food to only 50% of the lever presentations being followed by food. The introduction of partial reinforcement produced an immediate and durable increase in leverpressing. The findings of both experiments are consistent with predictions from Konorski’s model of classical conditioning if sign-tracking is considered as a “hunger CR.”  相似文献   

The isolation of stimulus-reinforcer associations established with multiple schedules     

Stanley J. Weiss 《Learning & behavior》1977,5(4):421-429

Multiple schedules established stimulus-reinforcer (S-S^R) associations on baselines in which equal response rates and patterning were maintained in all components. Subsequently, stimuli associated with an increase in reinforcement but no change in ongoing response rate were compounded. For one experimental group, free-operant avoidance (FOA) was programmed in tone and in light while variable-interval (VI) food reinforcement was effective in their simultaneous absence (T + L). The opposite stimulus-schedule combinations were programmed for the other. Both groups remained in their VI components 85% of the session on schedule preference tests, and on a stimulus compounding test emitted approximately 1.5 times as many responses to tone-plus-light (T + L) as to tone or light alone. This is the first report of additive summation to combined discriminative stimuli associated with only an increase in reinforcement. Nondifferentially trained controls who had the same contingency effective in tone, light, and T + L-VI or FOA—showed neither preference among schedule components or summation during stimulus compounding, indicating that nonassociative stimulus factors made no contribution to either resultant in the experimental animals. Evidence supporting an algebraic combination of response and reinforcement associations is presented, and functional similarities between transfer-of-control studies and the stimulus compounding tests of the experimental groups in the present experiment are discussed.  相似文献   

A concurrent assessment of the positive and negative properties of a signaled shock schedule     

John Harsh  Pietro Badia 《Learning & behavior》1974,2(3):168-172

A choice and a conditioned suppression procedure were used to assess concurrently the positive and negative properties of stimuli within a signaled shock schedule, Occasional shocks were presented to Ss responding on a variable-interval food schedule. Ss could choose whether shocks occurred alone or whether they were preceded by a 1-min signal. All Ss chose the signaled shock condition over the unsignaled one, even though food reinforced responding in the presence of the signal was suppressed. Rate of responding for food varied across stimulus conditions, with the lowest rate in the presence of the signal and the highest rate in its absence. An intermediate rate occurred under the unsignaled shock schedule. A safety analysis was applied to the data.  相似文献   

Variations of two temporal parameters in observing response procedures     

Kendall  Stephen B. 《Learning & behavior》1975,3(3):179-185

Temporal parameters were varied in two different observing response procedures. In Experiment I, concurrent variable-interval chain schedules were employed. Responding on one key led to either a stimulus correlated with reinforcement or a stimulus correlated with time-out. Responding on the other key led to a stimulus which ended either in reinforcement or time-out. The duration of the delay to reinforcement or time-out was varied, the delays for all three stimuli always remaining equal in a given phase. It was found that the longer the delay, the greater the preference for the observing response. In Experiment II a procedure was employed in which birds pecked during a “trial” to produce stimuli correlated with reinforcement or time-out at the end of the trial. The duration of the trial ending in time out was varied while the positive trial duration remained constant. It was found that the longer the duration of the negative trial, the greater the strength of observing responses. The results were interpreted as supporting the hypothesis that the value of a positive stimulus is a function of time spent in stimuli correlated with nonreinforcement.

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Second-order schedules: Manipulation of brief-stimulus duration at component completion     

Steven L. Cohen  Joan E. Hughes  D. Alan Stubbs 《Learning & behavior》1973,1(2):121-124

In a second-order schedule, fixed-interval components were reinforced according to a variable-interval schedule. A brief stimulus accompanied the completion of each fixed interval. Brief-stimulus duration was varied across conditions from 0.5 to 8 sec. Patterning was greater the longer the duration of the stimulus. Additionally, exposure to relatively long brief-stimulus durations enhanced patterning upon reexposure to shorter brief-stimulus durations.  相似文献   

Matching when the number of response alternatives is large     

H. L. Miller  Donald H. Loveland 《Learning & behavior》1974,2(2):106-110

Pigeons could choose between five concurrently available response keys, each associated with a different variable-interval schedule of reinforcement. A 2-sec changeover delay was also in effect on each key. In almost all cases, the relative number of responses to a key and the relative time spent at it were nearly equivalent to the relative number of reinforcements it produced. In addition, matching was observed between the relative number of reinforcements at a key and the relative number of changeovers to it.  相似文献   

Transfer of conditioned suppression and conditioned acceleration from instrumental to consummatory baselines     

Hank Davis  Donald Shattuck 《Learning & behavior》1980,8(2):253-257

Following training on a variable-interval food reinforcement schedule, rats were exposed to Pavlovian procedures which produced reliable conditioned suppression and conditioned acceleration of the leverpressing (instrumental) baseline. When free food was simultaneously made available in the test cage, all subjects spent the majority of each session “freeloading,” that is, eating food from a dish rather than leverpressing for it. When superimposed upon the freeloading baseline, the conditioned suppression and conditioned acceleration procedures affected the rate of pellet consumption identically in magnitude and direction to their previous effects on leverpressing. These results suggest a motivational mechanism for conditioned suppression and acceleration, rather than one which depends upon spurious punishment of specific response sequences.  相似文献   

Choice responding following multiple schedule training     

Eugene L. Edmon  Irwin Lucki  Michael G. Grisham 《Learning & behavior》1980,8(2):287-292

Pigeons’ choice responding on 10-sec interpolated probes was studied after baseline training on multiple variable-interval variable-interval schedules of food reinforcement. Unreinforced choice following training with three different relative reinforcement rates (Experiment 1), with a 3-ply multiple schedule (Experiment 2), and with three different relative reinforcement durations (Experiment 3) was examined. Least squares lines were fit to choice relative response rate and schedule relative response rate as functions of training relative reinforcement rate; choice slope was significantly greater than schedule slope in all three experiments. This result is counter to the prediction of Herrnstein’s (1970) theory that these slopes should not differ. Luce’s (1959) theory also failed to account for the data. It was concluded that choice responding was controlled by both approach to the stimulus associated with the smaller mean interreinforcer interval or the longer duration, and avoidance of the other stimulus.  相似文献   

Motivational mechanisms and schedule-induced behavioral stereotypy     

Vassiliki Papadouka  T. James Matthews 《Learning & behavior》1995,23(4):461-469

In two experiments, behavioral stereotypies elicited by scheduled presentations of food and water were compared. In Experiment 1, pigeons were exposed to a fixed-time 30-sec (FT 30-sec) schedule of food or water deliveries with a brightening keylight stimulus signaling time to the unconditioned stimulus (UCS) on each trial. Food and water presentations both produced terminal autoshaped keypecking that was similarly distributed in the trial but differed in response topography and persistence. Locomotor interim behavior was different in the two motivational conditions: With food presentations, it consisted of a “retreat” to the rear of the chamber after UCS termination, followed by “pacing” in the midportion of trials. The water schedule produced very little locomotor activity with no regular distribution in the trial. Experiment 2, using a random-time 30-sec (RT 30-sec) schedule, showed that the differences in interim locomotor behavior persisted in the absence of temporal predictability of the UCS and the keypecking terminal response. The results are taken to support Timberlake’s (1983a) behavior-system theory.  相似文献