Effects of fixed-ratio sample and choice response requirements upon oddity matching

Three pigeons were trained on oddity matching in which either 1, 4, 8, 16, or 32 sample-key observing responses were required to turn off the sample stimuli and turn on the comparison stimuli. Oddity accuracy increased when the observing-response requirement was raised and decreased when the requirement was lowered. Next, while the observing requirement was maintained at one response, the number of responses required to the comparison stimuli was either 1, 4, 8, 16, or 32. Under these conditions, choice was defined as the comparison that first accumulated the required number of responses. In general, increasing the comparison-response requirement decreased accuracy and lowering the comparison requirement increased accuracy. The fixed-ratio observing requirements appeared to facilitate control by stimuli serving an instructional function.     

Human Sensitivity To Concurrent Schedules Of Reinforcement: Effects Of Observing Schedule-correlated Stimuli

The determinants of human sensitivity to concurrent variable-interval variable-interval schedules of reinforcement have been difficult to identify, in part because of procedural differences separating published experiments. This experiment investigated vigilance to stimuli correlated with concurrent schedules. Across phases, 3 college students were provided with either no schedule-correlated stimuli, an observing response that provided brief access to the stimuli, or a contingency that required the subject to identify the stimulus correlated with the source of each obtained reinforcer. Sensitivity, as quantified by the generalized matching equation, was low when no stimuli were available. When the stimuli were response contingent, 1 subject observed them, and her behavior became more sensitive to the distribution of reinforcers across the concurrent schedules. When the procedure required discrimination of the stimulus correlated with each reinforcer, the other 2 subjects also observed the stimuli, and their schedule sensitivity was increased as well. These results implicate procedural differences, rather than inherent behavioral differences, as the source of differences in sensitivity to schedules of reinforcement between humans and nonhumans.     

Control of pigeons' matching-to-sample performance by differential sample response requirements

Pigeons were trained on a matching-to-sample task in which sample hue and required sample-specific observing behavior provided redundant, relevant cues for correct choices. On trials that involved red and yellow hues as comparison stimuli, a fixed-ratio 16 schedule (FR 16) was required to illuminate the comparisons when the sample was red, and a differential-reinforcement-of-low-rates 3-sec schedule (DRL 3-sec) was required when the sample was yellow. On trials involving blue and green hues as comparison stimuli, an FR 16 schedule was required when the sample was blue and a DRL 3-sec schedule was required when the sample was green. For some pigeons, a 0-sec delay intervened between sample offset and comparison onset, whereas other pigeons experienced a random mixture of 0-sec and 2-sec delay trials. Test trial performance at 0-sec delay indicated that sample-specific behavior controlled choice performance considerably more than sample hue did. Test performance was independent of whether original training involved all 0-sec delay trials or a mixture of 0-sec and 2-sec delays. Sample-specific observing response requirements appear to facilitate pigeons' matching-to-sample performance by strengthening associations between the observing response and correct choice.     

The contributions of static visual cues, nonvisual cues, and optic flow in distance estimation

By systematically varying cue availability in the stimulus and response phases of a series of same-modality and cross-modality distance matching tasks, we examined the contributions of static visual information, idiothetic information, and optic flow information. The experiment was conducted in a large-scale, open, outdoor environment. Subjects were presented with information about a distance and were then required to turn 180 before producing a distance estimate. Distance encoding and responding occurred via: (i) visually perceived target distance, or (ii) traversed distance through either blindfolded locomotion or during sighted locomotion. The results demonstrated that subjects performed with similar accuracy across all conditions. In conditions in which the stimulus and the response were delivered in the same mode, when visual information was absent, constant error was minimal; whereas, when visual information was present, overestimation was observed. In conditions in which the stimulus and response modes differed, a consistent error pattern was observed. By systematically comparing complementary conditions, we found that the availability of visual information during locomotion (particularly optic flow) led to an 'under-perception' of movement relative to conditions in which visual information was absent during locomotion.     

The effects of different component response requirements in multiple and concurrent schedules

Six pigeons were trained on multiple and concurrent schedules. The reinforcement rates were varied systematically (a) when lever pressing was required in one component and key pecking in the successive component; (b) when lever pressing was required in both multiple components; (c) when key pecking was required in both multiple components; and (d) when key pecking was required on one schedule and lever pressing was required on the concurrently-available schedule. Only the absolute level of responding was changed by different response requirements. Analyzed by the generalized matching law, performance under different response requirements resulted in a bias toward key pecking, and the measured response bias was the same in multiple and concurrent schedule arrangements. The bias in time measures obtained from concurrent schedule performance was reliably smaller than the obtained response biases. The sensitivity to reinforcement-rate changes was ordered: concurrent key-lever; multiple key-key; multiple lever-key; and, the least sensitive, multiple lever-lever. The results confirm that requirements of different topographical responses can be handled by the generalized matching law mainly in the bias parameter, but problems for this type of analysis may be caused by the changing sensitivity to reinforcement in multiple schedule performance as response requirements are changed.     

Response stereotypy without automaticity in pigeons

Previous research has shown that when pigeons are required to peck each of two keys four times in any order for reinforcement, stereotyped response sequences develop though they are not demanded by the task. The present experiment explored whether the functional value of sequence stereotypy was that sequences became automatized, freeing cognitive resources for other activities. Pigeons were exposed to variants of the task requiring four pecks on each key that differed in the degree of task stringency. Concurrent with the sequence task, pigeons were required to process the color of the keys in order to complete successfully either a matching or a conditional discrimination task. The delay between sequence execution and matching or discrimination choice was varied between 0 and 10 sec. Matching and discrimination accuracy were decreasing functions of delay, but the stringency of the concurrent sequence task had no effect on choice accuracy, suggesting that stereotyped sequences were automatized. However, the matching and discrimination tasks produced substantial disruptions of sequence performance, suggesting that stereotyped sequences were not automatized. The data were taken to suggest that response stereotypy need not imply automaticity.     

Local response-rate constancy on concurrent variable-interval schedules of reinforcement

Concurrent variable-interval schedules were arranged with a main key that alternated in color and schedule assignment, along with a changeover key on which a small fixed ratio was required to changeover. Acceptable matching was observed with pigeons in two replications, but there was a tendency toward overmatching. Local response rates were found to differ for unequal schedules of a concurrent pair: local response rate was greater for the variable-interval schedule with the smaller average interreinforcement interval, but qualifications based on an interresponse-time analysis were discussed. In a second experiment, two 3-minute variable-interval schedules were arranged concurrently, and the experimental variable was the changeover procedure: either a changeover delay was incurred by each changeover or a small fixed ratio on a changeover key was required to complete a changeover. Changeover delays of 2 and 5 seconds were compared with a fixed-ratio changeover of five responses. The response output on the main key (associated with the variable-interval schedules) was greater when a changeover delay was arranged than when a fixed ratio was required to changeover. A detailed analysis of stripchart records showed that a 2-second delay generated an increased response rate for 3 seconds after a changeover, while the fixed-ratio requirement generated an increased rate during the first second only, followed by a depressed response rate for 2 seconds.     

Feature saliency affects delayed matching of an attended feature

We examined how top-down attentional modulation and bottom-up stimulus saliency interact with feature memory. Experiment 1 used a delayed-matching-to-sample (DMS) task to examine the relative saliency between features by observing the relative accuracy of recognition at different stimulus durations. Feature salience decreased according to the following order: colour, form, and texture. In a modified DMS task (Experiments 2 and 3), participants were required to attend to one of three features and ignore the others. After a delay, they were required to choose which of the two test stimuli matched the reference stimulus on the attended feature, disregarding other task-irrelevant features. The target was either identical to the reference stimulus or mismatched the reference stimulus on one of the irrelevant features. The results showed that colour matching was affected neither by a form change nor by a texture change. Form matching was affected by a colour change, and texture matching was affected by a colour or form change. These results are consistent with the relative saliency hypothesis. Even when all features of an attended object are maintained, a relatively more salient task-irrelevant feature can interfere with the delayed recognition of a less salient feature.     

Reducing overselective stimulus control with differential observing responses

Overselective stimulus control refers to discriminative control in which the number of controlling stimuli is too limited for effective behavior. Experiment 1 included 22 special‐education students who exhibited overselective stimulus control on a two‐sample delayed matching task. An intervention added a compound identity matching opportunity within the sample observation period of the matching trials. The compound matching functioned as a differential observing response (DOR) in that high accuracy verified observation and discrimination of both sample stimuli. Nineteen participants learned to perform the DOR and two‐sample delayed matching accuracy increased substantially for 16 of them. When the DOR was completely withdrawn after 10 sessions, accuracy declined. In Experiment 2, a more gradual withdrawal of DOR requirements showed that highly accurate performance could be maintained with the DOR on only a proportion of trials for most participants. The results show that DOR training may lead to a general improvement in observing behavior.     

Observing responses and informative stimuli

Pigeons were trained on a trial procedure. A trial began with the illumination of a pecking key by a white light. After a fixed interval, a key peck could turn the key to one of two equi-probable colors and produce a delayed trial outcome—an equi-probable occurrence of either reinforcement or nonreinforcement. After a trial, the key turned dark and the trial ended. The response could be made into an observing response by correlating the key colors with the outcomes. Response rates in the fixed interval then increased to a level greater than when the colors and outcomes were uncorrelated. In another phase, the response produced only the colors. The trial outcomes occurred some seconds after the fixed interval without a response being required. Correlating the colors with the outcomes again increased response rates. In a second experiment, a further condition was added in which reinforcement was the outcome on every trial. Response rates were lower than when there were equi-probable reinforcement and nonreinforcement outcomes with correlated colors, and about the same as when there were equi-probable outcomes with uncorrelated colors. The results suggest that stimuli providing information about the probability of reinforcement are themselves reinforcing.     

Role of response imagery on stimulus recognition*

This experiment investigated the role of response imagery on recognition of stimulus terms following associative training. Ss learned to associate 12 high-imagery or low-imagery responses with trigram stimuli by the study-associative matching procedure. Half the pairs were consistently paired and half were re-paired anew on each trial. Following associative training, Ss were given a stimulus recognition and an associative matching task The results indicated that the probability of stimulus recognition, given correct associative matching, was greater when the responses were high-imagery rather than low-imagery. In contrast, no rehable response imagery effects were found for the probability of stimulus recognition, given incorrect associative matching. It was argued that the locus of the response imagery effect was primarily during retrieval rather than during encoding.     

Delayed matching to two-picture samples by individuals with and without disabilities: an analysis of the role of naming

Delayed matching to complex, two-picture samples (e.g., cat-dog) may be improved when the samples occasion differential verbal behavior. In Experiment 1, individuals with mental retardation matched picture comparisons to identical single-picture samples or to two-picture samples, one of which was identical to a comparison. Accuracy scores were typically high on single-picture trials under both simultaneous and delayed matching conditions. Scores on two-picture trials were also high during the simultaneous condition but were lower during the delay condition. However, scores improved on delayed two-picture trials when each of the sample pictures was named aloud before comparison responding. Experiment 2 replicated these results with preschoolers with typical development and a youth with mental retardation. Sample naming also improved the preschoolers' matching when the samples were pairs of spoken names and the correct comparison picture matched one of the names. Collectively, the participants could produce the verbal behavior that might have improved performance, but typically did not do so unless the procedure required it. The success of the naming intervention recommends it for improving the observing and remembering of multiple elements of complex instructional stimuli.     

Reduction of stimulus overselectivity with nonverbal differential observing responses

Three individuals with mental retardation exhibited stimulus overselectivity in a delayed matching-to-sample task in which two sample stimuli were displayed on each trial. Intermediate accuracy scores indicated that participants could match one of the samples but not both of them. Accuracy in a baseline condition was compared to accuracy with a differential observing response procedure. This procedure prompted participants to make simultaneous identity-matching responses that required observation and discrimination of both sample stimuli. These observing responses were never followed by differential consequences. When observing responses were prompted, participants' accuracy scores improved. In a return to the baseline condition, when differential observing responses were no longer prompted, accuracy returned to intermediate levels. The results show that stimulus overselectivity can be greatly reduced by a behavioral intervention that controls observing behavior and verifies discrimination, but that exposure to such procedures alone may be insufficient for lasting benefits.     

Depth matching with visible diplopic images: Stereopsis or vernier alignment

In order to prevent subjects from actually performing a judgment of vernier alignment between the double images rather than matching stereoscopic depth of the test objects, various precautions have previously been taken, e.g., using inexperienced subjects who were ignorant of the experimental situation and possible matching criteria. In the experiment reported here, a subject was given training in observing double images and the matching problems were also discussed. The subject was then instructed to perform stereoscopic depth judgments. The comparison between these data and data based on vernier alignment judgments under similar conditions showed that knowledge about the experimental situation and the vernier alignment criterion did not interfere with the subject’s task of matching the stereoscopic depth between visible double images.     

EEG mu rhythm and imitation impairments in individuals with autism spectrum disorder

Imitation ability has consistently been shown to be impaired in individuals with autism. A dysfunctional execution/observation matching system has been proposed to account for this impairment. The EEG mu rhythm is believed to reflect an underlying execution/observation matching system. This study investigated evidence of differential mu rhythm attenuation during the observation, execution, and imitation of movements and examined its relation to behaviorally assessed imitation abilities. Fourteen high-functioning adults with autism spectrum disorder (ASD) and 15 IQ- and age-matched typical adults participated. On the behavioral imitation task, adults with ASD demonstrated significantly poorer performance compared to typical adults in all domains of imitation ability. On the EEG task, both groups demonstrated significant attenuation of the mu rhythm when executing an action. However, when observing movement, the individuals with ASD showed significantly reduced attenuation of the mu wave. Behaviorally assessed imitation skills were correlated with degree of mu wave attenuation during observation of movement. These findings suggest that there is execution/observation matching system dysfunction in individuals with autism and that this matching system is related to degree of impairment in imitation abilities.     

A matching advantage for dynamic human faces

In a series of three experiments, we used a sequential matching task to explore the impact of non-rigid facial motion on the perception of human faces. Dynamic prime images, in the form of short video sequences, facilitated matching responses relative to a single static prime image. This advantage was observed whenever the prime and target showed the same face but an identity match was required across expression (experiment 1) or view (experiment 2). No facilitation was observed for identical dynamic prime sequences when the matching dimension was shifted from identity to expression (experiment 3). We suggest that the observed dynamic advantage, the first reported for non-degraded facial images, arises because the matching task places more emphasis on visual working memory than typical face recognition tasks. More specifically, we believe that representational mechanisms optimised for the processing of motion and/or change-over-time are established and maintained in working memory and that such 'dynamic representations' (Freyd, 1987 Psychological Review 94 427-438) capitalise on the increased information content of the dynamic primes to enhance performance.     

Transfer of hue matching in pigeons.

Pigeons were trained on a modified three-key matching-to-sample procedure, in which only one comparison key (rather than two) was lighted after an observing response to the center-key standard. Pecks on keys of matching comparison hues were reinforced. When non-matching hues appeared as the initially lighted comparisons, the nonmatching hue terminated and the matching hue appeared on the other side key only if the pigeon did not peck the nonmatching comparison for 4.8 sec. Pecks to the nonmatching hue reset the 4.8-sec delay interval. Three hues were used during acquisition. During transfer tests, two novel hues were substituted individually or together for one or two of the training hues. Latencies to the novel side-key hue were shortest when a novel matching hue appeared as the standard on the center key, and were essentially identical to baseline matching latencies. In contrast, when a novel hue appeared as either a standard or comparison in a nonmatching combination, latencies increased with increasing separation between the noevel hue and the nonmatching hue. These transfer data demonstrate the concept of hue matching.     

Response Mode Bias in the Formation of Preference: Boundary Conditions of the Prominence Effect

Prior research has discovered that the most prominent attribute has greater influence on the formation of preference in choice versus matching tasks. We extend the research on this phenomenon, which is known as the prominence effect (Tversky, Sattath, & Slovic, 1988), by examining its generalizability and by providing insight into the psychological processes involved. The effects of task characteristics (i.e., the number of attributes and alternatives) and the effects of subject characteristics (i.e., processing goal) on the prominence effect were examined. In the first experiment we found that the prominence effect reverses when the number of attributes increases from two to four. That is, the prominent attribute is given greater weight in matching tasks rather than in choice tasks. A second experiment demonstrated that processing goal does influence the robustness of the prominence effect. We found that the influence of the prominent attribute on the formation of preference did not differ in choice and matching tasks when subjects′ processing goal was to form an overall impression of each of the alternatives. A third experiment, which explored the interaction between the response mode and processing goal in the four attribute case replicated this finding. Findings from Experiment 1 were also extended so that the reverse prominence effect was found when subjects processing goal was to memorize the information. Implications of these results are discussed.     

Revisiting the role of bad news in maintaining human observing behavior

Results from studies of observing responses have suggested that stimuli maintain observing owing to their special relationship to primary reinforcement (the conditioned-reinforcement hypothesis), and not because they predict the availability and nonavailability of reinforcement (the information hypothesis). The present article first reviews a study that challenges that conclusion and then reports a series of five brief experiments that provide further support for the conditioned-reinforcement view. In Experiments 1 through 3, participants preferred occasional good news (a stimulus correlated with reinforcement) or no news (a stimulus uncorrelated with reinforcement) to occasional bad news (a stimulus negatively correlated with reinforcement). In Experiment 4 bad news was preferred to no news when the absence of stimulus change following a response to the bad-news option was reliably associated with good news. When this association was weakened in Experiment 5 the results were intermediate. The results support the conclusion that information is reinforcing only when it is positive or useful. As required by the conditioned-reinforcement hypothesis, useless information does not maintain observing.     

Response stereotypy without automaticity: Not quite involuntary attention in the pigeon

Previous research has shown that when pigeons are required to peck each of two keys four times in any order for reinforcement, stereotyped response sequences develop, though they are not required by the task. However, despite this stereotypy, sequences are not automatized. They require sufficient attention that sequence performance is disrupted by a concurrent, delayed matching-to-sample task. In the present experiments, pigeons were required to execute response sequences and delayed matching-to-sample concurrently. Experiment 1 showed that the matching task disrupts sequence performance even when the matching sample stimuli do not have to be processed concurrently with sequence execution. The presence of sample stimuli during sequence execution seems to command attention even if the sample stimuli are also available for processing when sequences are not being executed. Experiment 2 used the directed forgetting technique to show that pigeons do seem able to ignore sample stimuli if they are given information that tells them they will not be required to remember those stimuli later. Together, the experiments suggest attentional mechanisms in the pigeon that are not quite involuntary.