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Biomedical subjects

E A Wasserman

Publications and source records attributed to E A Wasserman.

At least 37 records · Page 2Linked to original sources
PubMed1996

The what and the where of the pigeon's processing of complex visual stimuli.

Eight pigeons were trained on a go-no go visual discrimination involving 1 S+ and 15 S- s. The 16 discriminative stimuli were black-and-white line drawings created by the factorial combination of 4 different geometric shapes (wedge, cylinder, cone, handle) in 4 different spatial locations (right, left, above, below) in relation to a common shape (cube). All of the pigeons readily learned this complex visual discrimination. Each bird's pecking behavior was controlled by both attributes of the line drawings, but somewhat stronger stimulus control was exerted by the location of the added component than by its shape. Across all 8 pigeons, there was an inverse relation between stimulus control by component shape and component location. These results document pigeons' joint processing of "what" and "where" information in visual discrimination learning.

Animals↗
PubMed1996

The pigeon's recognition of drawings of depth-rotated stimuli.

Four experiments used a four-choice discrimination learning paradigm to explore the pigeon's recognition of line drawings of four objects (an airplane, a chair, a desk lamp, and a flashlight) that were rotated in depth. The pigeons reliably generalized discriminative responding to pictorial stimuli over all untrained depth rotations, despite the bird's having been trained at only a single depth orientation. These generalization gradients closely resembled those found in prior research that used other stimulus dimensions. Increasing the number of different vantage points in the training set from one to three broadened the range of generalized testing performance, with wider spacing of the training orientations more effectively broadening generalized responding. Template and geon theories of visual recognition are applied to these empirical results.

Animals↗
PubMed1996

Cyclic responding by pigeons on the peak timing procedure.

The present experiment examined whether discrimination learning shapes the single-peaked response distributions usually obtained with the peak procedure. Two sources of learning in pigeons were disclosed: learning to respond near the time of reinforcement on fixed interval (FI) trials and learning to withhold responding once the FI duration had elapsed on peak interval (PI) trials. Pigeons also produced a highly unexpected second peak in responding on nonreinforced PI trials at 3 times the FI duration. Follow-up experiments showed that a 1:4 FI:PI duration ratio supported double peaks, but only 1 peak was obtained with a 1:8 FI:PI duration ratio. Finally, 4 peaks could be observed on extra-long PI trials under a 1:4:8 FI:PI:PI ratio procedure. The multiple-peaked response distributions are an unprecedented finding that present a major challenge to any theory of time perception.

Animals↗
PubMed1996

Effects of spatial rearrangement of object components on picture recognition in pigeons.

Five pigeons were first trained to discriminate among line drawings of four objects: a watering can, an iron, a desk lamp, and a sailboat. The birds were then tested with eight versions of each object, in which the object's components were vertically and horizontally rearranged. The pigeons displayed different degrees of generalization decrement to the different scrambled versions of the objects. Two analyses helped to clarify the nature of the varied accuracy scores. First, cluster analyses disclosed subsets of components that were related to test performance. Second, although the clusters varied somewhat across birds for a given object, there was reliable concordance among the subjects in their rankings of the individual scramblings, suggesting that the pigeons may have attended to common aspects of the drawings.

Animals↗
PubMed1995

Animal mind and the argument from design.

The argument from design has played an important role in the history of philosophy and biology. Paley, the 19th-century theologian, was struck by the bodily complexity and adaptive fit of animals to their environments; he used the argument from design to prove the existence of God. Darwin, however, provided the natural evolutionary mechanisms that eliminated the need for positing a divine creator to explain the structure of animals; he was thus able to treat the historical problem of organic evolution by providing a historical solution. Today, some students of behavior are similarly struck by the complexity of animals' actions and their adaptive fit to the environment. Like Paley, they use the argument from design, but to prove the existence of a conscious designer inside the head of the animal--the mind. This mentalistic approach suffers from many of the philosophical and empirical problems that plagued similar efforts in the past.

Animals↗
PubMed1995

Pigeons show same-different conceptualization after training with complex visual stimuli.

Eight pigeons were first trained to peck 1 button in the presence of 16 distinct 4 x 4 arrays of identical pictures and to peck a 2nd button in the presence of 16 distinct 4 x 4 arrays of nonidentical pictures. Later, they were tested with 16 other same and 16 other different stimulus arrays involving untrained pictures. Performance to the testing arrays greatly exceeded chance levels, thus suggesting same-different conceptualization by pigeons.

Animals↗
PubMed1993

Judging interevent relations: from cause to effect and from effect to cause.

Stimulus competition was studied in college students' correlational judgments in a medical decision-making setting. In accord with prior findings, subjects making cause-to-effect (predictive) judgments discounted a stimulus event that was moderately correlated with a target event when rival stimuli were more highly correlated with the effect. However, subjects making effect-to-cause (diagnostic) judgments were not at all disposed to discount a stimulus event which was moderately correlated with a target event when rival stimuli were more highly correlated with the cause. The theoretical implications of these results are considered in connection with associative and mentalistic models of causal attribution.

Adolescent↗
PubMed1992

Discrimination of contour-deleted images by pigeons.

Three experiments attempted to determine which properties of pictorial representations of objects control their discrimination by pigeons. A particular focus was whether the representation mediating such discriminations could be described by the simple viewpoint-invariant primitive volumes of Biederman's (1987) recognition-by-components theory of object recognition or by Cerella's (1990) particulate features. In all 3 experiments, pigeons were first trained to discriminate drawings of 4 stimulus objects with half of the contour deleted but with the component geons postulated by Biederman's theory recoverable. Discrimination accuracy was then compared for test items containing the original particulate features, affording the retrieval of the original component geons, or having neither of these properties of the training stimuli. Although response accuracy was significantly greater when the component geons of the original objects were retrievable, measurable control over recognition by the particulate features of the objects and by their specific locations was also found. The results are consistent with the idea of component geon recognition as one of the important factors in object discrimination.

Animals↗
PubMed1991

Forebrain ischemia induces selective behavioral impairments associated with hippocampal injury in rats.

Two groups of rats were tested on a variety of motor and cognitive tasks after either 10 minutes of two-vessel occlusion forebrain ischemia (n = 8) or sham operative procedures (n = 6). Histological injury was absent in the sham-operated group. In the ischemic group, hippocampal injury was restricted to field CA1, while damage in the neocortex and caudoputamen was sparse. Motor tests performed on postoperative days 18 and 28 revealed no significant differences between the ischemic and sham-operated groups. Retention performance of a radial maze discrimination task was impaired, with a significant but transient increase in both working and reference memory errors. Passive avoidance acquisition and retention were not significantly affected, although conclusions concerning the utility of this task must be reserved because of variability in the behavior of the sham-operated rats. Morris maze spatial navigation (place learning) and open-field activity were insensitive to treatment group. These functional results are consistent with the observed histological injury and what is known about hippocampal injury and behavior, and they provide further guidance for the development of neurological assays appropriate for discriminating outcome from forebrain ischemia in rats.

Animals↗
PubMed1990

Contributions of specific cell information to judgments of interevent contingency.

College students considered the possible effect of an experimental drug on a skin rash. The information came from a 2 x 2 contingency table involving receipt or nonreceipt of the drug and improvement or nonimprovement of the rash: Cell A = receipt-improvement; Cell B = receipt-nonimprovement; Cell C = nonreceipt-improvement; Cell D = nonreceipt-nonimprovement. Without numerical information. Ss judged cells to be ordered A greater than B greater than C greater than D. The same order held when the contribution of each cell was derived from the contingency judgments of other subjects given numerical information. No such consistency was seen when one group of Ss made both judgments: whether individual Ss equally or unequally assessed the importance of the four cells, their contingency estimates showed cell use to be ordered A greater than B greater than C greater than D. These findings may result from strong biases that Ss harbor in processing contingency information.

Adult↗
PubMed1989

Secondary generalization and categorization in pigeons.

In Experiment 1, one group of pigeons learned to classify a set of stimuli into the human language classes cat, flower, car, and chair (categorization); another group learned to classify the same set into arbitrary classes (pseudocategorization). Then, both groups were trained on a new categorization task and their performance compared to that of a control group that had no initial classification training. Hull's (1943) notion of secondary generalization (generalization that is not based on physical similarity but on mediating associations) predicts that categorization experience will facilitate the learning of a new categorization task, whereas pseudocategorization experience will impair it. However, in Experiment 1, performance on the new categorization task was not differently affected by prior experience. In Experiment 2, pigeons initially trained to classify a set of 48 stimuli (original training) were later trained to classify a subset of four of these stimuli using new responses (reassignment training). Then, they were tested on the 44 remaining stimuli. Performance better accorded with original than with reassignment training, indicating that categorization training did not lead to the formation of equivalence classes of stimuli, in which the equivalence relationship is mediated by secondary generalization. The lack of evidence of secondary generalization implies that our pigeons failed to meet Lea's (1984) criterion for conceptual behavior.

Journal Article↗
PubMed1987

Tolerance to antinociceptive effects of morphine without tolerance to its effects on schedule-controlled behavior.

The development of tolerance to behavioral effects of morphine was investigated in rats that responded on a two-lever, multiple-trial, multiple differential-reinforcement-of-low-rate fixed-ratio (mult DRL FR) schedule of food presentation. Stable performances were maintained when sessions were conducted just twice per week. The effects of cumulative doses of morphine (1.0-8.0 mg/kg) or chlordiazepoxide (CDP; 4.0-32.0 mg/kg) were evaluated once per week; saline injections were given in the intervening sessions. The effects of saline and morphine on nociception were also evaluated in hot-plate tests conducted on the same subjects 15 min after selected operant sessions. Initially, morphine produced dose-related decreases in response rates and reinforcement rates in the DRL and FR components as well as significant increases in hot-plate response latencies. Following weekly administration of morphine (1.0-8.0 mg/kg) for 10 weeks, there was little or no tolerance to its effects on operant behavior. In contrast, complete tolerance developed to the antinociceptive effects of morphine. These results suggest that tolerance to various behavioral effects of morphine may be dissociated, and that the loss of reinforcement may be insufficient by itself to produce tolerance to effects of morphine on operant behavior. Additionally, whereas CDP initially produced only dose-related decreases in DRL and FR response rates, following weekly morphine the smaller doses of CDP (4.0-16.0 mg/kg) produced increases in response rates.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1987

Delayed temporal discrimination in pigeons: A comparison of two procedures.

A within-subjects comparison was made of pigeons' performance on two temporal discrimination procedures that were signaled by differently colored keylight samples. During stimulus trials, a peck on the key displaying a slanted line was reinforced following short keylight samples, and a peck on the key displaying a horizontal line was reinforced following long keylight samples, regardless of the location of the stimuli on those two choice keys. During position trials, a peck on the left key was reinforced following short keylight samples and a peck on the right key was reinforced following long keylight samples, regardless of which line stimulus appeared on the correct key. Thus, on stimulus trials, the correct choice key could not be discriminated prior to the presentation of the test stimuli, whereas on position trials, the correct choice key could be discriminated during the presentation of the sample stimulus. During Phase 1, with a 0-s delay between sample and choice stimuli, discrimination learning was faster on position trials than on stimulus trials for all 4 birds. During Phase 2, 0-, 0.5-, and 1.0-s delays produced differential loss of stimulus control under the two tasks for 2 birds. Response patterns during the delay intervals provided some evidence for differential mediation of the two delayed discriminations. These between-task differences suggest that the same processes may not mediate performance in each.

Journal Article↗
PubMed1986

College students' responding to and rating of contingency relations: The role of temporal contiguity.

Two experiments investigated the role of temporal contiguity in college students' responding to and rating of contingency relations during operant conditioning. Schedules were devised that determined when but not whether appetitive or aversive events would occur. Subjects' reports concerning the schedules were obtained by means of a 200-point rating scale, anchored by the phrases "prevents the light from occurring" (-100) and "causes the light to occur" (+100). When tapping a telegraph key advanced the time of point gain, responding was maintained or increased and subjects gave positive ratings. When tapping a telegraph key advanced the time of point loss, subjects also gave positive ratings, but responding now decreased. When key tapping delayed the time of point gain, responding decreased and subjects gave negative ratings. When key tapping delayed the time of point loss, subjects also gave negative ratings, but responding now increased. These findings implicate response-outcome contiguity as an important contributor to causal perception and to reinforcement and punishment effects. Other accounts-such as those stressing the local probabilistic relation between response and outcome or the molar correlation between response rate and outcome rate-were seen to be less preferred interpretations of these and other results.

Journal Article↗
PubMed1984

Chronic diazepam administration and appetitive discrimination learning: acquisition versus steady-state performance in pigeons.

Chronic injections of 2 mg/kg diazepam disrupted both steady-state performance and new discrimination learning in pigeons. However, the time course of disruption differed for each of the two tasks, i.e., steady-state performance was briefly disrupted early, whereas acquisition showed a more persistent delayed disruption. The difference was interpreted as resulting from a dual effect of diazepam on behavior. The early performance disruption was thought to reflect a general nonspecific sedative action of the drug, while the delayed disruption of learning was interpreted as the result of diazepam's selective interference with acquisition processes. Some support for rapid adjustment to the sedative effects of diazepam was found, but there was no evidence for the development of physiological tolerance to diazepam-induced acquisition deficits.

Animals↗
PubMed1982

Further remarks on the role of cognition in the comparative analysis of behavior.

Recent interest in comparative psychology has stimulated much research and debate concerning cognitive processes in animal behavior. The present paper relates to this general area by treating particular issues in the analysis of comparative cognition: specifically, how cognition is inferred from animal behavior; whether the postulation of intervening cognitive processes furthers our understanding of behavior; and how rival approaches help advance the science of behavior.

Journal Article↗