The Influence of Background Stimuli on Summation in Autoshaping

Five experiments examined the factors that determine whether or nor summation will occur when experimental stimuli are presented on a television screen for autoshaping with pigeons. In Experiment 1 there were periods when the television screen was illuminated white and periods when it was dark. When conditioning was conducted during the white periods, then summation was observed if the test trials were conducted with a white screen during the intertrial interval. Summation was not found when conditioning was conducted during the dark periods, no matter how testing was conducted. The remaining experiments demonstrated that summation will occur if at least some of the conditioning trials are conducted with the experimental stimuli being accompanied by white illumination in the remainder of the television screen. It was not necessary for this illumination to persist into the interval between trials. These findings indicate that summation is influenced by the similarity of the patterns of stimulation that are used for training and testing.     

The Function of Intensity in the Spatial Summation of Subliminal Stimuli in the Retina

Each of 12 rats was subjected to a conventional three-phase behavioral contrast paradigm. No positive behavioral contrast was observed in any S, although 11 rats showed very strong extinction effects. Three rats showed negative induction, eight showed no increase in response rate in the constant component, while one rat showed first a positive then a negative induction effect. The results were discussed in terms of both Reynolds' and Terrace's hypothesis and related to the recent research on autoshaping.     

Apparent Incentive Contrast Effects in Autoshaping with Rats

The effects of shifts in reward quality and quantity on Pavlovian acquisition were studied in rats. In Experiment 1, animals preexposed to unsignaled food pellets, 10% sucrose solution, or home cage controls subsequently received autoshaping training (response-independent lever-pellet or lever-solution pairings, in three groups each). Unsignaled preexposure to sucrose solution facilitated autoshaping for pellets (relative to unshifted controls), whereas unsignaled preexposure to pellets retarded autoshaping for sucrose solution. In Experiment 2, unsignaled preexposure to 30% sucrose solution impaired acquisition reinforced by food pellets, relative to 2% solution. Using a choice procedure, Experiment 3 demonstrated that rats prefer pellets to either 2 or 10% sucrose solutions, but they prefer the 30% solution to the pellets. Experiment 4 demonstrated the facilitatory effect after an upward shift in reward magnitude rather than quality (from 1 to 12 pellets), but provided weaker evidence for retardation following a downward magnitude shift. Experiment 5 was similar to Experiment 4, except that animals received autoshaping training from the outset. No evidence of successive positive contrast was obtained, but there was a significant successive negative contrast effect. Moreover, extinction was faster after acquisition with 12 pellets rather than 1. These results suggest the presence of incentive contrast effects under Pavlovian training conditions.     

Autoshaping in the goldfish

The target-striking response of the goldfish was classically conditioned to target-light color, the effectiveness of the pairing (of color and reinforcement) being demonstrated by appropriate controls.     

Autoshaping of key pecking in pigeons with negative reinforcement

Pigeons exposed to gradually increasing intensities of pulsing electric shock pecked a key and thereby reduced the intensity of shock to zero for 2 min. Acquisition of key pecking was brought about through an autoshaping process in which periodic brief keylight presentations immediately preceded automatic reduction of the shock. On the occasions of such automatic reduction of shock preceding the first measured key peck, little or no orientation to the key was observed. Observations of pigeons with autoshaping of positive reinforcement also revealed little evidence of orientation toward the key.     

Within-subject Partial Reinforcement Extinction Effect in Autoshaping

Three autoshaping experiments explored the extinction of various keylight stimuli conditioned with partial and continuous reinforcement within the same pigeon subjects. Extinction of autoshaped keypecking proceeded more slowly in a stimulus trained with 50% (Experiment 1) and 25% (Experiment 2) reinforcement compared with a stimulus given 100% reinforcement. Experiment 3 found conditioning with 75% reinforcement to generate more rapid extinction than that with 25% reinforcement. These results have both theoretical and methodological implications for the study of extinction.     

Autoshaping with common and distinctive stimulus elements, compact and dispersed arrays

Four groups of pigeons were trained with a standard autoshaping procedure in which a brief fixed-duration interval always followed by a grain delivery alternated with a longer variable-duration interval never associated with grain delivery. One of two stimuli was always presented during each interval. One of them contained three black dots and a black star on a green background; the other contained four black dots on a green background. The four elements of each stimulus were arranged in a more compact array for two groups and in a more dispersed array for the other two groups. Which of the two stimuli preceded grain delivery was counterbalanced within each pair of groups. The speed of occurrence of the first autoshaped peck was not affected by whether the stimulus containing the distinctive star element preceded grain delivery, but autoshaping was faster when the stimulus arrays were compact than when they were dispersed. During 560 response-independent training trials that followed the first autoshaped peck, this pattern reversed; both discriminative control over responding and the relative frequency of pecking the stimulus that preceded grain delivery were greater for the two groups where this stimulus contained the discriminative element than for the two groups where it contained only common elements. During subsequent testing with stimuli containing only a single element each, the distinctive feature was responded to proportionately more often by the two groups for which it had been an element of the stimulus preceding grain delivery than by the two groups for which it had been an element of the stimulus complex that never was associated with grain delivery. These data add further support to the hypothesis that the initial occurrence of autoshaped responding and its subsequent maintenance are not affected by the same variables. They also suggest that automaintenance is as sensitive as response-dependent training to the presence or absence of a distinctive stimulus element among several common elements and that this sensitivity appears to be independent of the specific method used for presenting the stimuli during automaintenance.     

Autoshaping and automaintenance: a neural-network approach

This article presents an interpretation of autoshaping, and positive and negative automaintenance, based on a neural-network model. The model makes no distinction between operant and respondent learning mechanisms, and takes into account knowledge of hippocampal and dopaminergic systems. Four simulations were run, each one using an A-B-A design and four instances of feedfoward architectures. In A, networks received a positive contingency between inputs that simulated a conditioned stimulus (CS) and an input that simulated an unconditioned stimulus (US). Responding was simulated as an output activation that was neither elicited by nor required for the US. B was an omission-training procedure. Response directedness was defined as sensory feedback from responding, simulated as a dependence of other inputs on responding. In Simulation 1, the phenomena were simulated with a fully connected architecture and maximally intense response feedback. The other simulations used a partially connected architecture without competition between CS and response feedback. In Simulation 2, a maximally intense feedback resulted in substantial autoshaping and automaintenance. In Simulation 3, eliminating response feedback interfered substantially with autoshaping and automaintenance. In Simulation 4, intermediate autoshaping and automaintenance resulted from an intermediate response feedback. Implications for the operant-respondent distinction and the behavior-neuroscience relation are discussed.     

Autoshaping and automaintenance of a key-press response in squirrel monkeys

Following exposure for a minimum of 500 to 600 trials, three of four naive squirrel monkeys eventually pressed a response key, illumination of which always preceded delivery of a food pellet. Three other naive monkeys did not press the key when the pellets were delivered randomly with respect to key illumination. Despite some similarities to autoshaping using pigeons, the data indicate many points of difference when squirrel monkeys are used as subjects. Although key-food pairings were shown to be important in the acquisition of the key-press response, they were ineffective in maintaining the response when either a negative response-reinforcer dependency was introduced, or when there was no scheduled response-reinforcer dependency (fixed trial). Not all demonstrations of autoshaping can be considered to be under the control of those processes that are primarily responsible for the phenomena obtained in pigeons.     

Autoshaping, random control, and omission training in the rat

The role of the stimulus-reinforcer contingency in the development and maintenance of lever contact responding was studied in hooded rats. In Experiment I, three groups of experimentally naive rats were trained either on autoshaping, omission training, or a random-control procedure. Subjects trained by the autoshaping procedure responded more consistently than did either random-control or omission-trained subjects. The probability of at least one lever contact per trial was slightly higher in subjects trained by the omission procedure than by the random-control procedure. However, these differences were not maintained during extended training, nor were they evident in total lever-contact frequencies. When omission and random-control subjects were switched to the autoshaping condition, lever contacts increased in all animals, but a pronounced retardation was observed in omission subjects relative to the random-control subjects. In addition, subjects originally exposed to the random-control procedure, and later switched to autoshaping, acquired more rapidly than naive subjects that were exposed only on the autoshaping procedure. In Experiment II, subjects originally trained by an autoshaping procedure were exposed either to an omission, a random-control, or an extinction procedure. No differences were observed among the groups either in the rate at which lever contacts decreased or in the frequency of lever contacts at the end of training. These data implicate prior experience in the interpretation of omission-training effects and suggest limitations in the influence of stimulus-reinforcer relations in autoshaping.     

Autoshaping a leverpress in rats with lateral, medial, or complete septal lesions

Rats with either control operations or lateral, medial, or complete septal lesions received 600 trials of leverpress training using an autoshaping procedure, i.e., food delivery followed a 10 s illuminated lever presentation, or occurred immediately after a leverpress. Rats with complete septal lesions acquired the leverpress faster than controls and had more food-tray entries per minute during the first 100 trials than the other groups. Rats with lateral or medial septal lesions had leverpress and food-tray entries equivalent to controls. The facilitation of autoshaping a leverpress may partially be explained by the general increase in motor reactivity to stimuli found following septal lesions.     

Timing of the CS-US Interval by Pigeons in Trace and Delay Autoshaping

Evidence for timing during Pavlovian trace and delay conditioning trials was sought by exposing pigeons to differentially cued trial durations of 18, 24, and 60 sec. For a delay group, one of three visual patterns (CSs) was presented on a key for the entire trial; for a trace group, each CS was 12 sec in duration, creating trace gaps of 6, 12, or 48 sec. Intertrial interval duration was 48 sec. The most informative data were provided by measures of time spent proximal to the CS (proximity). Stimulus control was evident in that proximity was inversely related to trial duration for both groups. Evidence for timing was obtained from the relation of relative proximity during each CS to relative elapsed trial time for individual birds. The obtained superposition of the three functions for each bird is consistent with a scalar timing process and implies that subjects learned the temporal relation between each CS and the unconditioned stimulus. Associative status of the CSs differed between groups and among CS-US intervals, as reflected in proximity data during a higher-order test in which the CSs served as reinforcers. The results are consistent with a two-dimensional model of Pavlovian conditioning according to which the associative strength accruing to a CS is orthogonal to the temporal information encoded for that stimulus.     

Verbal Establishing Stimuli: Testing the Motivative Effect of Stimuli in a Derived Relation with Consequences

The Psychological Record - The present study examined whether the presentation of stimuli in equivalence relations with consequences increases the operant behavior that produces these consequences....     

材料类型和任务可预测性在任务转换中的作用

以阿拉伯数字和汉字数字为材料,采用奇偶判断和大小判断任务交替呈现范式,考察材料类型和任务可预测性在任务转换中的作用。结果发现:(1)对阿拉伯数字和汉字数字的反应时无显著差异,转换代价差异不显著;(2)不可预测任务反应时显著长于可预测任务,转换任务和重复任务都显示了基于可预测性的准备效应。表明材料类型对任务转换无影响,重复和转换任务都存在一般的任务控制更新过程。     

Stimulus Generalization and the Peak Shift with Movement Stimuli

Stimulus generalization is suggested as an alternative method for examination of the “novelty? problem in motor learning. These experiments demonstrated that stimulus generalization occurs using simple movements as stimuli. The phenomenon of the “peak shift? in post-discrimination generalization gradients was also examined. The first experiment demonstrated that a peak shift occurred using linear movements as stimuli and that the magnitude of the peak shift increased as the difference between the training stimuli decreased. The second experiment showed similar results when the stimuli consisted of a range of movements rather than a single movement length. The final experiment provided evidence that perception of movement length is influenced by the magnitude of an immediately preceding movement. The relevance of these studies to current motor-learning theory is discussed.     

Stimuli previously associated with reinforcement mitigate resurgence

Resurgence refers to the recurrence of an extinguished target behavior following subsequent suspension of alternative reinforcement. Delivery of reinforcers during extinction of alternative behavior has been shown to mitigate resurgence. The present experiment aimed to determine whether delivering stimuli associated with reinforcers during resurgence testing similarly mitigates resurgence. Three groups of rats pressed target levers for food according to variable‐interval 15‐s schedules during Phase 1. In Phase 2, lever pressing was extinguished, and an alternative nose‐poke response produced alternative reinforcement according to a variable‐interval 15‐s schedule. Food reinforcement was always associated with illumination of the food aperture and an audible click from the pellet dispenser during Phases 1 and 2. Phase 3 treatments differed between groups. For one group, nose poking continued to produce food and food‐correlated stimuli. Both of these consequences were suspended for a second group. Finally, nose poking produced food‐correlated stimuli but not food for a third group. Target‐lever pressing resurged in the group that received no consequences and in the group that received only food‐correlated stimuli for nose poking. Resurgence, however, was smaller for the group that received food‐correlated stimuli than for the group that received no consequences for nose poking. Target‐lever pressing did not increase between phases in the group that continued to receive food and associated stimuli. Thus, delivery of stimuli associated with food reinforcement after suspension of food reduced but did not eliminate resurgence of extinguished lever pressing. These findings contribute to potential methodologies for preventing relapse of extinguished problem behavior in clinical settings.     

Changes in Immobility Responses in Rat Pups with Maternal Stimuli

Presentation of maternal stimuli to an isolated rat pup results in what has been called “comfort” responses, as indicated by both behavioral and physiological quieting. This experiment investigated the role of passive maternal stimuli on tonic immobility and dorsal immobility in 9- and 15-day-old rat pups. Although these stimuli appeared ineffective in inducing tonic immobility, presentation of the mother did produce an increase in duration of dorsal immobility in 15-day-old pups. This increase in the dorsal immobility response may reduce struggling in the presence of the mother and thereby aid the mother in transporting the infant back to the nest.     

Summation relations and portions of stuff

According to the prevalent ‘sum view’ of stuffs, each portion of stuff is a mereological sum of its subportions. The purpose of this paper is to re-examine the sum view in the light of a modal temporal mereology which distinguishes between different varieties of summation relations. While admitting David Barnett’s recent counter-example to the sum view (Barnett, Philos Rev 113:89–100, 2004), we show that there is nonetheless an important sense in which all portions of stuff are sums of their subportions. We use our summation relations to develop, as an alternative to the sum view, an analysis of stuffs that distinguishes between the ways in which different sorts of stuffs are sums of their subportions.

Autoshaping as a psychophysical paradigm: Absolute visual sensitivity in the pigeon

A classical conditioning procedure (autoshaping) was used to determine absolute visual threshold in the pigeon. This method provides the basis for a standardized visual psychophysical paradigm.