Partial reinforcement in autoshaping with pigeons

The acquisition, maintenance, and extinction of autoshaped responding in pigeons were studied under partial and continuous reinforcement. Five values of probability of reinforcement, ranging from .1 to 1.0, were combined factorially with five values of intertrial interval ranging from 15 to 250 sec for different groups. The number of trials required before autoshaped responding emerged varied inversely with the duration of the intertriai interval and probability of reinforcment, but partial reinforcement did not increase the number of reinforcers before acquisition. During maintained training, partial reinforcement increased the overall rate of responding. A temporal gradient of accelerated responding over the trial duration emerged during maintenance training for partial reinforcement groups, and was evident for all groups in extinction. Partial reinforcement groups responded more than continuous reinforcement groups over an equivalent number of trials in extinction. However, this partial-reinforcment extinction effect disappeared when examined in terms of the omission of “expected” reinforcers.     

Behavior patterns in pigeons during autoshaping with an incremental conditioned stimulus

Pigeons were trained on a variant of the autoshaping procedure in which a keylight stimulus of increasing brightness was used to signal the passing of a 30-sec interfood interval (IFI). Key-pecking developed in all subjects within the first session (65 trials). Within trials, pecking began midway through the IFI, increased throughout the remainder, and decreased just before food delivery. Other behavioral stereotypies were also recorded: Low light levels were associated with a retreat to the rear of the test chamber, and medium light levels (during the midportion of the IFI) were associated with high rates of pacing toward and away from the food source. Probe trials revealed that pecking, pacing, and retreat were all under strong stimulus control; that is, when the light was held constant at its lowest or highest brightness, or when the brightness ramp was presented in reverse order, the behavior pattern almost invariably remained tied to stimulus brightness. Results are discussed in terms of associative and nonassociative sources of the form and sequential characteristics of the behavior.     

Blocking of first- and second-order autoshaping in pigeons

In Experiment 1, the development of autoshaped pecking to a keylight signaling food was blocked if the keylight was presented only in conjunction with another stimulus already established as a signal for food, even though the blocking stimulus (either an overhead light or a train of clicks) never elicited pecking itself. In Experiment 2, pigeons came to peck a white keylight which signaled the presentation of a red keylight which had earlier been established as a first-order signal for food, but this second-order autoshaping was blocked if the white keylight was presented only in conjunction with the houselight or clicker which had previously signaled the presentation of the first-order stimulus. Second-order autoshaping was thus blocked in the same way as was first-order autoshaping.     

Sensitivity of pigeons to prereinforcer and postreinforcer delay

Delay between choice and receipt of reinforcement (prereinforcer delay) and delay between receipt of reinforcement and the next opportunity to choose (postreinforcer delay) were varied in a discretetrials choice paradigm using four pigeons. The pigeons consistently chose the reinforcer with the smaller prereinforcer delay. Variations in postreinforcer delay did not affect choice unless prereinforcer delays were equal. The results support previous findings that prereinforcer delays contribute disproportionately to the effects of rate of reinforcer access on choice in pigeons.     

The acquisition of trace supraordinate stimulus control in pigeons

Match-to-sample and oddity-from-sample problems with four colors were acquired by two pigeons under the supraordinate control of a line tilt superimposed on samples, Since the supraordinate stimulus terminated before the comparison stimuli were presented, accurate matching and oddity performance indicated trace stimulus control as well, The temporal extent of trace control was assessed in one subject by presenting probes—trials without a line tilt on the sample—in which the basis of correct responding was the supraordinate stimulus presented on the previous trial, Trace supraordinate control did not extend between trials, Subsequently, the delay between the termination of the supraordinate stimulus and the presentation of the comparison stimuli was gradually increased within a trial, Both subjects were able to perform matching and oddity over longer delays, and eventually on probe trials, although accuracy decreased, Results were discussed in terms of instructional stimulus control and memory.     

Attention shifts during matching-to-sample performance in pigeons

Two pigeons performed a matching-to-sample task in which a color, a line orientation, or both, might appear on the sample. Stimulus control by (attention to) the color and line components of a compound sample was measured when (a) either component might be relevant (i.e., appear as a comparison stimulus on that trial), and (b) when only one component was relevant. Degree of stimulus control by a given component of the compound sample was higher when only it was relevant than when either component might be relevant. Because the matching-to-sample task separated sample inspection from response choice, interpretation of the results in terms of response competition was ruled out. Because the training procedure led to shifts in stimulus control by the components of the compound sample, explanation of previous matching-to-sample results in terms of reduced perceptual clarity of compound samples was also ruled out. Thus, variations in stimulus control by components of the compound sample were interpreted as showing shifts in attention to the components of the compound sample.     

Systematic errors in pigeons’ memory for event duration: Interaction between training and test delay

Pigeons trained to choose different stimuli following short- and long-duration signals make disproportionately more “short” choices (i.e., “choose-short errors”) following an increase in the retention interval and more “choose-long errors” following a decrease in this delay. The present experiment provided a systematic investigation of how these selective errors depend on the relationship between the training delay and the test delay. Pigeons were first trained with a 0-sec delay between the signal (2- or 8-sec food presentations) and the choice stimuli (red- and blue-lit keys). On subsequent test trials with 5- and 10-sec delays, choose-short errors predominated. Next, the birds were trained with a constant 10-sec delay and then tested with shorter or longer delays on some trials. The birds now responded accurately and without selective errors at the 10-sec training delay, but made choose-long errors at shorter delays and choose-short errors at longer delays. Finally, the birds were trained with a constant 20-sec delay and then tested with shorter and longer delays. Choose-long errors again appeared at shorter test delays, choose-short errors at longer test delays, and no differential errors at the 20-sec training delay. The selectivity of these errors generally increased with the absolute difference between the training and test delay. Theoretical implications of these results are discussed.     

Serial discrimination reversal learning in pigeons as a function of intertrial interval and delay of reinforcement

Pigeons learned a series of reversals of a simultaneous red-green visual discrimination. Delay of reinforcement (0 vs. 2 sec) and intertrial interval (ITI; 4 vs. 40 sec) were varied across blocks of reversals. Learning was faster with 0-sec than with 2-sec delays for both ITI values and faster with 4-sec ITIs than with 40-sec ITIs for both delays. Improvement in learning across successive reversals was evident throughout the experiment, furthermore, even after more than 120 reversals. The potent effects of small differences in reinforcement delay provide evidence for associative accounts and appear to be incompatible with accounts of choice that attempt to encompass the effects of temporal parameters in terms of animals’ timing of temporal intervals.     

Intertrial interval and unconditioned stimulus durations in autoshaping

Four groups of pigeons were exposed to an autoshaping procedure in which a 20-sec key illumination preceded the presentation of response-independent grain, The groups differed according to the duration of feeder access and the intertriai intervals, If feeder durations are not included in the time between trials, two of the groups had identical intertriai intervals. If feeder durations are included, each of the other two groups was identical to one of the first two in terms of the intertriai interval, The speed of acquisition and maintained measures of responding were directly related to the duration of the interval from food offset to signal onset, Groups exposed to equivalent intertriai intervals and different feeder durations did not differ from one another on these measures, The results were interpreted as evidence that feeder durations were not included in the functional intertrial interval and that feeder duration, per se, did not affect autoshaped responding.     

Consummatory response latency and the stimulus-reinforcer relation in autoshaping

Autoshaping procedures with pigeons were used to assess the susceptibility of unconditioned response (UR) activity to Pavlovian relations between stimulus and reinforcer events. Foodpeck latency (a measure of UR activity) was investigated as a function of the interval between stimulus (keylight) and reinforcer (grain) presentations, and of the stimulus-reinforcer contingency, that is, the conditional probabilities of reinforcer delivery in the presence and absence of the stimulus. Four experiments indicated that food-peck latency was sensitive to both manipulations. Generally, conditions that led to higher keypeck rates were associated with shorter latencies. Thus, UR potentiation was demonstrated. However, when the bird’s location prior to grain delivery was fixed by imposing a keypeck-reinforcer contingency, UR potentiation vanished; it then reappeared when the location constraint was removed. Visual observations supported the conclusion that food-peck latency effects were mediated by approach/withdrawal tendencies generated by the stimulus-reinforcer relation. Implications of these results for expectancy theory are discussed.     

Acquisition with partial and continuous reinforcement in pigeon autoshaping

Contemporary time accumulation models make the unique prediction that acquisition of a conditioned response will be equally rapid with partial and continuous reinforcement, if the time between conditioned stimuli is held constant. To investigate this, acquisition of conditioned responding was examined in pigeon autoshaping under conditions of 100% and 25% reinforcement, holding intertrial interval constant. Contrary to what was predicted, evidence for slowed acquisition in partially reinforced animals was observed with several response measures. However, asymptotic performance was superior with 25% reinforcement. A switching of reinforcement contingencies after initial acquisition did not immediately affect responding. After further sessions, partial reinforcement augmented responding, whereas continuous reinforcement did not, irrespective of an animal's reinforcement history. Subsequent training with a novel stimulus maintained the response patterns. These acquisition results generally support associative, rather than time accumulation, accounts of conditioning.     

Sign tracking in domesticated quail with one trial a day: Generality across CS and US parameters

When the conditioned stimulus (CS) is located some distance from the unconditioned stimulus (US), pairings of the CS and US can yield either conditioned approach to the CS (sign tracking) or conditioned approach to the US (goal tracking). However, goal tracking is the more common outcome, and, because of that, goal tracking has come to serve as a “standard” measure of associative learning in several laboratories. In contrast, in previous studies of sexual conditioning with domesticated quail, only sign tracking was observed. In the present study, quail continued to show sign tracking rather than goal tracking whether or not the US was highly localized (Experiment 1), whether food or a sexual US was used (Experiment 2), whether the CS was mobile or immobile (Experiment 3), and whether the CS was 91 or 233 cm from the US compartment (Experiment 4). The present findings encourage caution in the routine use of goal tracking as a measure of learning. The possible mechanisms of goal tracking are discussed in terms of occasion setting and behavior systems theory.     

Two-choice conditional discrimination performance of pigeons as a function of reward expectancy,prechoice delay,and domesticity

In a discrete-trial two-choice conditional discrimination task, pigeons which received food for a correct choice following the presentation of one cue and water for a correct choice following another cue performed better than pigeons which received food and water equally often in both cases when delays of several seconds intervened between the conditional cue and choice stimuli presentations. These results suggest that feedback properties of reinforcer-specific expectancies can be important in conditional discrimination learning in pigeons. An additional finding was that wild-caught pigeons regularly exhibited a higher percentage of correct choices than domestic subjects.     

The role of primary reinforcement and overt movements in autoshaping in the pigeon

Following sessions of free grain delivery, a transparent shield was placed over the magazine, which made food unavailable. Different groups of pigeons then “observed” positive, zero, or negative correlations between the keylight and inaccessible grain. Keypecks were rare in all groups. Next, the shield was removed, and a transfer-test was given in which all subjects were exposed to keylight presentations followed by available grain. The previously positive group pecked sooner and more frequently than the others. A second experiment, which yielded similar results, excluded the possibility that approaches to the keylight during the observation phase had mediated learning in the first experiment. These findings were discussed in relationship to operant and Pavlovian analyses of autoshaping.     

Form perception and attention in pigeons

This report selectively reviews the authors’ research on stimulus control by visual forms. Most studies employed visual search of computer-generated displays, and the main behavioral measure was search reaction time. Pigeons classify simple line forms much as do humans, and there was some evidence for feature extraction, though a search asymmetry probe failed to identify several putative features. Dimensional analysis revealed a new quantitative relation between similarity and the probability of detecting a target. It also identified candidates for integral and separable stimulus dimensions. Similarity and set-size variables influenced the extent to which attention was engaged. Further studies addressed the manner in which attention is focused, revealing relationships between priming and search images. In these cases, attention to a selected form is probably driven by a top-down assessment of predictability.     

How student and parent goal orientations and classroom goal structures influence the math achievement of African Americans during the high school transition

This study examined the effects of student and parent goal orientations and perceived classroom goal structures on grades and self-efficacy in mathematics during the high school transition. From a sample of 50 African American families living in a low-income school district, student survey data and open-ended parent interviews were examined. There were three significant findings. First, students who espoused more mastery goals in high school mathematics experienced more positive changes in self-efficacy and grades in mathematics during the high school transition than did their peers. Second, students who perceived more mastery and less performance goal structures in their high school math classrooms experienced more positive changes in mathematics self-efficacy during the transition than did their peers. Third, adolescents whose parents espoused mastery goals had higher grades than did their peers whose parents did not espouse mastery goals. Results indicate that mastery goals may be more influential in determining achievement and motivation in mathematics for African American students than are performance goals during the high school transition.     

Choice and percentage reinforcement in pigeons

Pigeons responded on a two-key concurrent chains choice procedure with the same level of percentage reinforcement on each key. During the initial links, a choice response on either key occasionally produced a conditioned reinforcer—which on one key was associated with a 15-sec, and on the other key with a 30-sec, interreinforcement interval—or an extinction stimulus. In Part 1, the initial links were equal. With successive decreases in the probability of a reinforcer, choice shifted from preference for the 15-sec terminal link toward indifference. In Part 2, the initial links were unequal and were arranged so that the shorter initial link preceded the 30-sec terminal link. At a high probability of a reinforcer, the pigeons again preferred the 15-sec terminal link. However, at a low probability, the pigeons reversed and preferred the alternate key. It was concluded that the conditioned reinforcers tended to become functionally equivalent at a low probability of a reinforcer, despite the nominally different interreinforcement intervals, with the result that choice was then modulated by the relative size of the initial links. The data are inconsistent with the view that choice and the strength of conditioned reinforcers are isomorphic with the reduction in delay to reward correlated with terminal link stimuli.     

Students' achievement goal orientations and their behavioral and emotional engagement: Co-examining the role of perceived school goal structures and parent goals during adolescence

The role of perceived school goal structures and parent goals in predicting adolescents' goal orientations and their behavioral and emotional engagement in the classroom was examined in the present study. Surveys were given to a sample of 271 seventh- and ninth-grade students. Path analyses showed that (a) perceived school mastery goal structures and parent mastery goals predicted student mastery goal orientation, perceived school and parent performance goals predicted student performance-avoidance goal orientation, whereas performance-approach orientation was only predicted by perceived parent performance goals; (b) perceived school and parent mastery goals predicted behavioral but not emotional engagement directly as well as indirectly through the mediation of student mastery goal orientation; (c) behavioral and emotional engagement were predicted by student mastery goal orientation. Results are discussed in relation to current theory and their implications for promoting adaptive patterns of learning in the school and the family context.     

Changes in the perceived classroom goal structure and pattern of adaptive learning during early adolescence

Despite a recent increase in research on the associations between classroom goal structures, motivation, affect, and achievement, little is known about the effects of changes in the perceived classroom goal structure as students move from one grade level to another. Comparisons of students who perceived an increase, decrease, or no change in the mastery and performance goal structures of their classrooms during the transition to middle school and across two grades within middle school revealed that changes in the mastery goal structure were more strongly related to changes in cognition, affect, and performance than were changes in the performance goal structure. The most negative pattern of change was associated with a perceived decrease in the mastery goal structure.