Response-independent events in the behavior stream

The metaphor of the behavior stream provides a framework for studying the effects of response-independent food presentations intruded into an environment in which operant responding of pigeons was maintained by variable-interval schedules. In the first two experiments, response rates were reduced when response-independent food was intruded during the variable-interval schedule according to a concomitantly present fixed-time schedule. These reductions were not always an orderly function of the percentage of response-dependent food. Negatively accelerated patterns of key pecking across the fixed-time period occurred in Experiment 1 under the concomitant fixed-time variable-interval schedules. In Experiment 2, positively and negatively accelerated and linear response patterns occurred even though the schedules were similar to those used in Experiment 1. The variable findings in the first two experiments led to three subsequent experiments that were designed to further illuminate the controlling variables of the effects of intruded response-independent events. When the fixed and variable schedules were correlated with distinct operanda by employing a concurrent fixed-interval variable-interval schedule (Experiment 3) or with distinct discriminative stimuli (Experiments 4 and 5), negatively accelerated response patterns were obtained. Even in these latter cases, however, the response patterns were a joint function of the physical separation of the two schedules and the ratio of fixed-time or fixed-interval to variable-interval schedule food presentations. The results of the five experiments are discussed in terms of the contributions of both reinforcement variables and discriminative stimuli in determining the effects of intruding response-independent food into a stream of operant behavior.     

Modeling the effects of combined behavioral and pharmacological treatment on cigarette smoking: behavioral-economic analyses

Effects of different response requirements, response-independent cigarette puffs, and an alternative nondrug reinforcer on cigarette smoking were assessed in 2 experiments. The response requirement to obtain 2 puffs on a cigarette was manipulated while various numbers of response-independent puffs were provided (0, 6, or 12 in Experiment 1; 0 or 12 in Experiment 2). In Experiment 2, effects of response-dependent money ($0.25) on smoking were assessed within subjects. Response-dependent puff consumption decreased as price increased and as the number of response-independent puffs increased. Concurrently available money also decreased response-dependent smoking. The largest decrease in smoking occurred when puffs were at the highest price and when response-independent puffs and response-dependent money were both concurrently available. Findings suggest that combined pharmacological and behavioral interventions produce the greatest reductions in smoking.     

Disinhibition and spontaneous recovery of response decrements produced by free reinforcement in rats.

Conducted 3 experiments with a total of 16 Holtzman albino and 48 hooded male rats. After the Ss had been trained to barpress on a variable interval schedule of reinforcement, response rates were reduced by the introduction either of extinction or of a response-independent (free) reinforcement schedule. Spontaneous recovery was consistently obtained in extinction, especially when session durations were long. Under free reinforcement conditions there was little sign of spontaneous recovery, even when with high reinforcement rates response reduction was almost as rapid as in extinction. In disinhibition tests the introduction of noise produced increased responding under free reinforcement conditions but not in extinction. Results are interpreted as demonstrating a dissociation between spontaneous recovery and disinhibition. (23 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Topographic changes in responding during habituation to water-stream simulation in sea anemones (Anthopleura elegantissima).

Investigated habituation of contraction responses in 2 experiments with a total of 7 sea anemones using response-independent and response-dependent intertrial intervals (ITIs). In Exp I, repeated presentation of water-stream stimulation at 4 stimulus durations produced replicable response decrements in 5 out of 6 Ss in the response-independent ITI conditions. 3 Ss habituated repeatedly in the response-dependent ITI condition. Instances of both dishabituation and retention of habituation were observed, and habituation was often accompanied by changes in the topography of responding. In Exp II, habituation retention intervals were assigned values of 30, 60, or 90 min. 2 out of 3 Ss exhibited less responding at the shorter intervals. The data constitute nonassociative learning in individuals of a species lacking a central nervous system. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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 conditioned 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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ontogeny of persistence: immediate and long-term persistence in rats varying in training age between 17 and 65 days

In Experiment 1, six age groups of rats were trained to run an alley for either partial (PRF) or continuous reinforcement (CRF). Training was during a 2-day period starting at six different ages, and extinction was initiated about 12 hr later. There was a clear partial reinforcement extinction effect (PREE) at all ages and, particularly after PRF training, an inverse relationship between resistance to extinction and age. In Experiment 2, retention and durability of persistence as well as immediate persistence were tested following acquisition at three different ages. The immediate extinction tests confirmed the results of Experiment 1. In the delayed extinction tests, greater resistance to extinction following PRF than following CRF was found in all age groups after both the retention and durability manipulations. In neither test was there an effect of age in original acquisition on the magnitude of adult persistence. These experiments confirm earlier findings of remarkable persistence in rats trained and tested at weanling age, show that the persistence is even greater in pre-weanlings, and show that it is retained into young adulthood.     

Response-dependent versus response-independent presentation of cocaine: differences in the lethal effects of the drug

The drug self-administration paradigm is routinely used to assess the abuse liability of psychoactive compounds. Investigations of the behavioral effects of drug use, however, often involve the response-independent (experiment-delivered) administration of the compound. It is frequently assumed that response-independent presentation of a compound has the same effects as response dependent deliveries. The present study examined directly the effects of response-dependent (self-administered) versus response-independent (experimenter-delivered) administration of cocaine on food intake and lethality. Littermate triads were exposed to either cocaine (0.33 mg/infusion) or saline using a yoked-box procedure. One member of the triad self-administered the drug under a fixed-ratio 2 schedule. The other two rats received response-independent infusions of either cocaine or saline. Groups of triads were exposed to two different cocaine access conditions. Daily sessions were terminated after 6 h for one group and after the delivery of 80 infusions for the other. The mean number of infusions delivered each session was 47 (+/- 12) and 70 (+/- 11), respectively, for the 6-h and 80-infusion condition. Under the 80-infusion condition, response-independent infusions of cocaine resulted in a significantly higher rate of mortality compared to littermates self-administering identical amounts of the drug. A fewer number of deaths occurred under 6-h condition; however, only rats exposed to response-independent infusions died under both access conditions. These data indicate that the presence or absence of response dependency can profoundly alter the lethal effects of cocaine.     

Responses eliminated by noncontingent or negatively contingent reinforcement recover in extinction

Autoshaped key pecking in pigeons was eliminated by presenting reinforcers only during non-CS periods (negatively contingent reinforcement) or in both non-CS and CS periods (noncontingent reinforcement). In either case, when all reinforcers were subsequently removed (simple extinction), responding recovered strongly (Experiment 1). Recovery in extinction occurred only if the CS was in a conditioned state when non-CS reinforcers were introduced (Experiment 2). Recovery from noncontingent reinforcement was virtually complete, since total responding in extinction after response elimination was not less than in control groups extinguished without an intervening response-elimination phase (Experiment 3). Recovery also occurred for nonautoshapable, instrumentally reinforced key pecking (Experiment 4). The hypothesis that recovery is due to reinstatement of the non-CS stimulus conditions of acquisition (absence of food) was not supported (Experiments 5 and 6). Other accounts of recovery are considered.     

Observing response in goldfish (Carassius auratus).

In three experiments we established that goldfish make observing responses. In Experiment 1 fish were rewarded according to a mixed schedule of reinforcement with variable-interval (VI) and extinction (EXT) segments alternating randomly, each in the presence of the same exteroceptive stimulus. By striking a second target the fish in one group could produce a stimulus associated with food (S+). Fish in a second group could produce a stimulus associated with extinction (S–). Although few observing responses were made, fish apparently found aversive the S–. In Experiment 2 fish could respond on a multiple schedule of reinforcement with VI and EXT segments alternating randomly, each in the presence of a different exteroceptive stimulus or on a mixed schedule. Fish preferred the multiple side during VI segments but not during EXT segments until the predictive value of S+ and S– was reduced. In Experiment 3 fish were required to respond to produce S+ and S–. Again, fish preferred the multiple side during VI segments only. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The effects of acquisition training schedule on extinction and reinstatement of cocaine self-administration in male rats.

Partial reinforcement is known to increase resistance to extinction (Rn) relative to training with continuous reinforcement. This phenomenon, referred to as the partial reinforcement extinction effect, is one of the most robust in learning and conditioning studies. Experiment 1 investigated manipulations known to affect the partial reinforcement extinction effect and determined their possible relevance for drug use patterns. Male rats received intravenous cocaine self-administration training under partial reinforcement (FR-10) training or continuous reinforcement (FR-1) conditions with either a low (0.25 mg/kg infusion) or a high cocaine dose (1.00 mg/kg infusion). Animals were placed on an extinction (recurrent nonreward) schedule for 10 days (1-hr sessions) prior to being tested for cue-induced reinstatement (single 2-hr session). Experiment 2 involved acquisition of cocaine self-administration under FR-1 conditions of short training (15 days) or extended training (30 days) with a low dose (0.25 mg/kg infusion) or a medium dose (0.50 mg/kg infusion) of cocaine reward prior to extinction or reinstatement. Experiment 1 showed that rats trained with FR-10-high dose outcomes exhibited greater Rn than the remaining groups. Additionally, FR-10-high dose and FR-10-low dose rats were more likely to return to active drug seeking during the reinstatement test. In Experiment 2, rats trained under FR-1-medium dose conditions were more persistent during extinction following short acquisition training than comparable rats experiencing extended acquisition training. The reinstatement test was conducted following extinction, in which it was observed that overtraining under FR-1-medium dose reward schedules resulted in a decrease in the tendency to return to active drug seeking. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Partial reinforcement reduces the associative change produced by nonreinforcement.

Four autoshaping experiments with pigeons investigated the associative decrement produced by nonreinforcement of stimuli with a history of partial or continuous reinforcement. In each experiment, one keylight was reinforced on a 25% schedule and one on a 100% schedule. Then nonreinforced presentations of each stimulus were accompanied by different diffuse stimuli. In each experiment, the diffuse stimulus nonreinforced in the presence of the 100% excitor developed inhibition more rapidly than the diffuse stimulus nonreinforced in the presence of the 25% excitor. This inhibition was measured by transfer to another excitor reinforced on 100% (Experiment 1) or 25% (Experiment 2) schedule. The same difference was observed when the 25% excitor underwent a period of 100% reinforcement (Experiment 3) or was associatively stronger than the 100% excitor (Experiment 4). These results suggest that partial reinforcement acts in part to reduce the subsequent effectiveness of a nonreinforcement in producing associative change. This may contribute to the partial reinforcement extinction effect. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Facilitative and suppressive effects of punishment on species-typical aggressive display in Betta splendens.

Determined effects of moderate and intense punishment on aggressive behavior. Following either 15 or 45 massed presentations to a mirror, 35 Siamese fighting fish were punished for aggressive display (gill extension). Intense shock punishment led to complete suppression of the display. Recovery of the display depended on the level of habituation, i.e., only the fish given 15 mirror presentations prior to punishment showed recovery. Given "room" for an increase, a moderate level of punishment led to longer displays. A 2nd experiment with 6 Ss confirmed this latter finding with spaced (daily) blocks of trials. (23 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Variable ratio control of the spitting response in the archer fish (Toxotes jaculator).

Archer fish (Toxotes jaculator) hunt for prey by spitting water at airborne insects. In groups a fish engaged in spitting may lose its prey to a competitor and thereby experience nonreinforcement. To account for the maintenance of spitting in a competitive context, we propose that this species-specific response functions as an operant controlled by a socially induced variable ratio (VR) schedule of reinforcement. To determine whether VRs can control spitting, we trained 3 fish independently in a conditioning apparatus to spit at a food dispenser. After continuous reinforcement the fish were placed on extinction and then reconditioned. Then, they were exposed to increasing VR values, extinction, and reconditioning. All 3 fish showed evidence of conditioning, extinction, schedule control, and a partial reinforcement extinction effect. Operant control of spitting in isolated fish suggests that socially induced VRs can maintain spitting in groups. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulus salience and retrospective revaluation.

The effect of conditioning or extinguishing the more salient element of a previously reinforced compound on responding to the less salient element of that compound was assessed in rats. Experiment 1 established that the 2 elements making up an audiovisual compound differed significantly in salience. In Experiment 2A, compound conditioning was followed by either reinforcement or extinction of either the less or more salient element. On test, evidence of retrospective revaluation of the less salient element was found but not of the more salient element. In Experiment 2B, extinction of the more salient element was found to be more effective than its reinforcement in producing retrospective revaluation of the less salient element. The implications of these results are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Systematic nonlinearities in the perception of temporal intervals

Rats judged time intervals in a choice procedure in which accuracy was maintained at approximately 75% correct. Sensitivity to time (d') was approximately constant for short durations 2.0-32.0 s with 1.0- or 2.0-s spacing between intervals (n = 5 in each group, Experiment 1), 2.0-50.0 s with 2.0-s spacing (n = 2, Experiment 1), and 0.1-2.0 s with 0.1- or 0.2-s spacing (n = 6 in each group, Experiment 2). However, systematic departures from average sensitivity were observed, with local maxima in sensitivity at approximately 0.3, 1.2, 10.0, 24.0, and 36.0 s. Such systematic departures from an approximately constant d' are predicted by a connectionist theory of time with multiple oscillators and may require a modification of the linear timing hypothesis of scalar timing theory.     

Enhanced response acceleration or suppression produced by response-independent food presentations in rats with septal lesions

In two separate experiments, the response rates of rats with septal lesions were compared with those of control rats when response-independent food was presented while subjects were responding on a differential-reinforcement-of-low-rate schedule of reinforcement (Experiment 1) or according to a conjunctive differential-reinforcement-of-high-rate, fixed-ratio schedule (Experiment 2). Free-food deliveries resulted in acceleration of responding of subjects working on the low-rate schedule and in suppression of responding of those animals working on the high-rate schedule. Both of these effects were localized to a brief time period immediately following the free-food deliveries, and baseline rates of responding were not altered. The acceleration and suppression of responding that occurred on the respective schedules were greatly enhanced in rats with septal lesions. This finding supports the suggestion that these animals are hyperreactive to the reinforcing and/or eliciting properties of discrete stimulus events.     

Marking effects in Pavlovian trace conditioning.

[Correction Notice: An erratum for this article was reported in Vol 13(3) of Journal of Experimental Psychology: Animal Behavior Processes (see record 2008-10750-001). The last sentence in the second paragraph of the Discussion on page 128 should read as follows: "A second possibility is that in the marked ITI group, the marking of irrelevant events in the middle of the intertrial interval promoted associations between those events and food, which then interfered with the learning of an association between SI and food."] In four experiments we investigated pigeons' acquisition of a successive discrimination with a trace autoshaping procedure. The conditioned stimuli were 5-s presentations of colored key lights, one of which was followed by food after a 5-s delay. In Experiment 1, which used spatially defined cues, we found that acquisition of differential responding to the reinforced cue was facilitated when a brief flash of light immediately followed both reinforced and nonreinforced cues. Experiment 2 found a similar enhancement by the added light flash in a purely visual discrimination. Experiment 3 found that the flash facilitated learning only when presented immediately after the discriminative cues, and not when it occurred immediately before the cues or at the time of reinforcement. A fourth experiment found this facilitation effect only when the flash and reinforcement occurred on the same trial. These results are interpreted in terms of marking: The flash enhanced learning because it triggered a backward scan through recent memory to search for possible predictors. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of predictive accuracy on serial autoshaping: Evidence of orienting responses.

In four experiments we examined the influence of the predictive accuracy of the first element of a serial compound on the rate of autoshaped keypecking. In Experiment 1 a single group of pigeons received trials on two keys. On one key, Stimulus A was followed by either 5-s conditioned stimulus (CS) or a different CS of 20-s duration. On the other key, Stimulus B was also followed by different stimuli, but both were randomly either 5- or 20-s duration. All trials ended with the delivery of food. It was found that responding was faster during A than B. Experiment 2 replicated this finding by using a between-groups design. In Experiments 3 and 4 response rates were faster to A, which was followed on some trials by a 10-s duration CS and on others by a 30-s duration CS, than to B, which was always followed by a 10-s duration CS. These results can be most readily explained by the proposal that autoshaped keypecking consists of two kinds of response—a conditioned response and an orienting response—and the strength of the latter is inversely related to the accuracy with which the immediate consequences of the CS can be predicted. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Timing light and tone signals in pigeons.

Pigeons' ability to time light and tone stimuli was examined in four experiments. In Experiment 1, two groups of pigeons were trained to discriminate between 2- and 8-s durations of lights or tones and then were transferred to reversal or nonreversal discriminations in the alternate modality. Pigeons learned the light discrimination faster than the tone discrimination and showed immediate positive intermodal transfer from tone to light but not from light to tone. In Experiments 2–4, the peak procedure was used to study birds' timing of 15- and 30-s fixed-interval light and tone signals. Peak times on empty trials under baseline conditions closely approximated the length of fixed-interval signals. When pigeons were tested with time-outs and intermodal switches introduced midway through an empty trial, they tended to reset the timing mechanism and begin timing again from 0 s. With both estimation and production procedures, pigeons were less accurate when timing the tone stimuli than when timing the light stimuli. A comparison of these data with data from timing experiments with rats suggests several possible differences in timing processes between pigeons and rats. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The orienting response as an index of stimulus associability in rats.

The strength of the orienting response (OR) to a light and its associability was studied in three experiments. In Experiment 1, three groups of rats received serial conditioning in which the light served as the first element of a serial compound. For Group Diff the light was followed by a conditioned stimulus (CS) of 10-s duration on some trials and by a different CS of 30-s duration on others. For the other groups, the light was also followed by a different stimuli, but these had equivalent durations. This procedure resulted in stronger OR toward the light in Group Diff than in either of the other groups. In Experiments 2 and 3 the OR was stronger to a light that was followed by a 10-s CS on some trials and on a 30-s CS on others than to one that was followed by different CSs that were both randomly either 10 s or 30 s. Following this training, both excitatory and inhibitory conditioning with the light was faster in those groups for which the light elicited a strong rather than a weak OR. These results are most readily explained by the proposal that the strength of the OR toward a CS is determined by the accuracy with which the value of its immediate consequences can be predicted and that this OR can be used as an index of the associability of the CS. (PsycINFO Database Record (c) 2010 APA, all rights reserved)