Bias in self-evaluation: Signal probability effects

Two experiments examined apparent signal probability effects in simple verbal self-reports. After each trial of a delayed matching-to-sample task, young adults pressed either a “yes” or a “no” button to answer a computer-presented query about whether the most recent choice met a point contingency requiring both speed and accuracy. A successful matching-to-sample choice served as the “signal” in a signal-detection analysis of self-reports. Difficulty of matching to sample, and thus signal probability, was manipulated via the number of nonmatching sample and comparison stimuli. In Experiment 1, subjects exhibited a bias (log b) for reporting matching-to-sample success when success was frequent, and no bias or a bias for reporting failure when success was infrequent. Contingencies involving equal conditional probabilities of point consequences for “I succeeded” and “I failed” reports had no systematic effect on this pattern. Experiment 2 found signal probability effects to be evident regardless of whether referent-response difficulty was manipulated in different conditions or within sessions. These findings indicate that apparent signal probability effects in self-report bias that were observed in previous studies probably were not an artifact of contingencies intended to improve self-report accuracy or of the means of manipulating signal probability. The findings support an analogy between simple self-reports and psychophysical judgments and bolster the conclusion of Critchfield (1993) that signal probability effects can influence simple self-reports much as they do reports about external stimuli in psychophysical experiments.     

The Organization of Extrinsic Neurons and Their Implications in the Functional Roles of the Mushroom Bodies in Drosophila melanogaster Meigen

Although the importance of the Drosophila mushroom body in olfactory learning and memory has been stressed, virtually nothing is known about the brain regions to which it is connected. Using Golgi and GAL4–UAS techniques, we performed the first systematic attempt to reveal the anatomy of its extrinsic neurons. A novel presynaptic reporter construct, UAS-neuronal synaptobrevin–green fluorescent protein (n-syb–GFP), was used to reveal the direction of information in the GAL4-labeled neurons. Our results showed that the main target of the output neurons from the mushroom body lobes is the anterior part of the inferior medial, superior medial, and superior lateral protocerebrum. The lobes also receive afferents from these neuropils. The lack of major output projections directly to the deutocerebrum’s premotor pathways discourages the view that the role of the mushroom body may be that of an immediate modifier of behavior. Our data, as well as a critical evaluation of the literature, suggest that the mushroom body may not by itself be a “center” for learning and memory, but that it can equally be considered as a preprocessor of olfactory signals en route to “higher” protocerebral regions.     

Invisible Stimuli,Implicit Thresholds: Why Invisibility Judgments Cannot be Interpreted in Isolation

Some studies of unconscious cognition rely on judgments of participants stating that they have “not seen” the critical stimulus (e.g., in a masked-priming experiment). Trials in which participants gave invisibility judgments are then treated as those where the critical stimulus was “subliminal” or “unconscious,” as opposed to trials with higher visibility ratings. Sometimes, only these trials are further analyzed, for instance, for unconscious priming effects. Here I argue that this practice requires implicit assumptions about subjective measures of awareness incompatible with basic models of categorization under uncertainty (e.g., modern signal-detection and threshold theories). Most importantly, it ignores the potential effects of response bias. Instead of taking invisibility judgments literally, they would better be employed in parametric experiments where stimulus visibility is manipulated systematically, not accidentally. This would allow studying qualitative and double dissociations between measures of awareness and of stimulus processing per se.     

GAP-43 gene expression regulates information storage

Previous reports have shown that overexpression of the growth- and plasticity-associated protein GAP-43 improves memory. However, the relation between the levels of this protein to memory enhancement remains unknown. Here, we studied this issue in transgenic mice (G-Phos) overexpressing native, chick GAP-43. These G-Phos mice could be divided at the behavioral level into “spatial bright” and “spatial dull” groups based on their performance on two hidden platform water maze tasks. G-Phos dull mice showed both acquisition and retention deficits on the fixed hidden platform task, but were able to learn a visible platform task. G-Phos bright mice showed memory enhancement relative to wild type on the more difficult movable hidden platform spatial memory task. In the hippocampus, the G-Phos dull group showed a 50% greater transgenic GAP-43 protein level and a twofold elevated transgenic GAP-43 mRNA level than that measured in the G-Phos bright group. Unexpectedly, the dull group also showed an 80% reduction in hippocampal Tau1 staining. The high levels of GAP-43 seen here leading to memory impairment find its histochemical and behavioral parallel in the observation of Rekart et al. (Neuroscience 126: 579–584) who described elevated levels of GAP-43 protein in the hippocampus of Alzheimer’s patients. The present data suggest that moderate overexpression of a phosphorylatable plasticity-related protein can enhance memory, while excessive overexpression may produce a “neuroplasticity burden” leading to degenerative and hypertrophic events culminating in memory dysfunction.     

Recognition by the pigeon of stimuli varying in two dimensions

Pigeons served in four experiments, each of which involved about 44,000 discrete 1.2-sec trials under steady-state conditions. The first experiment scaled a short segment of the visual wavelength continuum; this dimension was then combined in a conditional discrimination with each of three others; time after reinforcement, tone frequency, and line tilt. In the two-stimulus experiments, the birds' responses were reinforced in the presence of only one stimulus combination: “582 nm” together with “2 min after reinforcement”, “3990 Hz”, or “vertical line”. Many other stimulus combinations also appeared equally often and went without reinforcement. The wavelength stimuli conformed to an equal-interval scale, and per cent response was generally linear with wavelength, when scaled on cumulative normal coordinates. The components of the compound stimulus were found to interact in a multiplicative fashion; when one component differed greatly from its reinforcement value, changes in the other component had relatively little effect. For the “time”-“wavelength” compound, this interaction appeared to be modified by the effects of set or attention. Certain response latency data are reported, and other combination rules are discussed.     

Contingency Horizon: on Private Events and the Analysis of Behavior

Skinner’s radical behaviorism incorporates private events as biologically based phenomena that may play a functional role with respect to other (overt) behavioral phenomena. Skinner proposed four types of contingencies, here collectively termed the contingency horizon, which enable certain functional relations between private events and verbal behavior. The adequacy and necessity of this position has met renewed challenges from Rachlin’s teleological behaviorism and Baum’s molar behaviorism, both of which argue that all “mental” phenomena and terminology may be explained by overt behavior and environment–behavior contingencies extended in time. A number of lines of evidence are presented in making a case for the functional characteristics of private events, including published research from behavior analysis and general experimental psychology, as well as verbal behavior from a participant in the debate. An integrated perspective is offered that involves a multiscaled analysis of interacting public behaviors and private events.     

Prepositional phrases spoken and heard

The relation between verbal and nonverbal behavior with common syntactic properties was investigated, using retarded and nonretarded children. Reinforcement was contingent on either verbal or nonverbal responses whereas responses of the other repertoire had no experimental consequences. Changes sometimes occurred in the unreinforced (collateral) repertoire, but they were always changes in the stimulus control of pre-existing topographies. A contingency involving responses of one repertoire never instated new topographies in the collateral repertoire. This suggested that the problem of “cross-modality generalization” should be reformulated to distinguish explicitly between instating new topographies and changing the stimulus control of pre-existing topographies. The result confirmed Skinner's hypothesis about “the same response spoken and heard” and clarified some anomalies in previous studies.     

Commentary on Malone: Who Founded Behaviorism?

Malone (The Behavior Analyst, 37, 1–12 2014) argued that the emergence of behaviorism was inevitable with or without Watson’s participation, mainly because protobehavioral ideas and dissatisfaction with classical structuralism were already widespread. However, the first premise is questionable because many of the ideas Malone cited were consistent with structuralism rather than behaviorism, and even if both premises were true they would not make the emergence of behaviorism—or anything else—inevitable. Historical evidence for inevitability is always retrospective and therefore always allows the logical fallacy of “after this, therefore because of this.” In the relevant real world Watson existed, he was a psychologist, he was the first to publish an article that described a “behaviorism,” and he promoted his behaviorism in later works. Stories about what would have happened without Watson’s participation are therefore counterfactual and this lack of historicity makes the stories fictional rather than scientific. In the real world, Watson founded behaviorism.     

Programming stimuli in matching to sample

In these investigations, a “teaching machine” was used to train pre-school and first-grade children in a series of progressively difficult discrimination tasks, leading up to matching to sample. Such training was much more efficient than training in the final discrimination alone. The errors the subjects made were found to be a functon both of the differences between consecutive discriminations (the “size of the steps” in the program) and the length of training on each discrimination. Theoretical and practical implications of these findings are discussed.     

Repeated acquisition in the analysis of rule-governed behavior

Five children, ranging in age from 3½ years to 5½ years, were taught various four-response chains using conditioned reinforcement. Experiment 1 investigated the effects of presenting “instruction” stimuli—a sequence of lights over the correct response buttons—to assess their role in facilitating the acquisition of a chain of responses. Without the “instruction” stimuli, children made many errors before responses were brought under the control of the programmed contingencies. When confronted with the same contingencies later in the day, these subjects made fewer errors. In contrast, in the presence of the “instruction” stimuli, subjects made virtually no errors. However, when the “instruction” stimuli were discontinued in the subsequent session, all 5 subjects made errors. In Experiment 2, the subjects were taught to verbalize the contingencies during the phase without the “instruction” stimuli. This resulted in errorless performance during the subsequent exposure to the same procedure, but errors nevertheless occurred again during reexposure to the procedure with the “instruction” stimuli discontinued.     

Teaching serial position sequences to monkeys with a delayed matching-to-sample procedure

Comparison was made of two methods for training monkeys to “observe” a two-member serial position sequence by pressing two consecutively lighted keys and then to “report” the sequence by pressing the same two keys in the same order but without the lights. A fading technique involving gradual elimination of brightness cues from “reporting” keys was found more effective than a no-fading procedure in which the cues remained bright during training and then were suddenly removed. Animals that failed to learn to report a new sequence with the no-fading procedure sometimes developed behavior incompatible with that desired. They made repeated and specific errors that prematurely terminated trials of the sequence to-be-learned, even though the correct key was cued by a bright light. They behaved appropriately, however, on succeeding trials of other sequences. Thus, the errors were followed by trials on which reinforcement occurred. Manipulation of this contingency indicated its importance in maintaining the stereotyped error patterns.     

The associative relation underlying autoshaping in the pigeon

Fifteen pigeons were exposed to either response-independent or response-dependent schedules of water reinforcement, whereby water was injected directly into the unrestrained pigeons' mandibles. Key-contact responses were released by a lighted key correlated with water, but not by a lighted key uncorrelated with water. A negative response-reinforcer contingency suppressed autoshaped key-contact responses, resulting in responding directed away from the lighted key. In all pigeons, water injected directly into the mandibles elicited a consummatory fixed-action pattern of “mumbling” and swallowing. The lighted key correlated with water released a broader set of both appetitive and consummatory responses: approach to the lighted key, “bowing”, “rooting”, “mumbling”, and swallowing. Key-contact responses were “rooting” and “mumbling” motions of the beak on the surface of the key. Views of autoshaping based on stimulus substitution or stimulus surrogation do not fully explain the origin of autoshaped responses not previously elicited by the reinforcer. The present findings are consonant with views of conditioning that emphasize the large degree of biological pre-organization in conditioned response patterns, and the importance of associative factors in the control of such patterns.     

Unbiased and unnoticed verbal conditioning: the double agent robot procedure

Subjects who were told they were “experimenters” attempted to reinforce fluent speech in a supposed subject with whom they spoke via intercom. The supposed subject was to say nouns, one at a time, on request by the “experimenter”, who reinforced fluent pronunciation with points. Actually, the “experimenter” was talking to a multi-track tape recording, one track of which contained fluently spoken nouns, the other track containing disfluently spoken nouns. If the “experimenter's” request for the next noun was in a specified form a word from the fluent track was played to him as reinforcement; requests in any other form produced the word from the disfluent track. Repeated conditioning of specific forms of requests was accomplished with two subject-“experimenters,” who were unable to describe changes in their own behavior, or the contingencies applied. This technique improved upon an earlier method that had yielded similar results, but was less thoroughly controlled against possible human bias.     

RESPONDING MAINTAINED UNDER INTERMITTENT SCHEDULES OF ELECTRIC-SHOCK PRESENTATION: “SAFETY” OR SCHEDULE EFFCTS?

Four experiments were conducted in which lever pressing by squirrel monkeys was maintained under multiple, mixed, or chained schedules of electric-shock presentation. In the first two experiments, a multiple schedule was employed in which a fixed-interval schedule of shock presentation alternated with a signaled two-minute component. Initially, no events were scheduled during the two-minute component (a safety period). In the first experiment, the safety period was “degraded” by introducing and systematically increasing the frequency of periodic shocks presented during that component. In the second experiment, the proportion of overall safe time to unsafe time was decreased by decreasing the value of the fixed-interval schedule while holding constant shock frequency during the two-minute component. In the third experiment, the overall arrangement was changed from a multiple to a mixed schedule in an attempt to determine whether fixed-interval responding would be maintained when a single exteroceptive stimulus was associated with both components. In the fourth experiment, the overall arrangement was changed from a multiple to a chained schedule in an effort to determine whether fixed-interval responding would be maintained when its consequence was presentation of a signaled “unsafe” period. Fixed-interval responding was well maintained under all experimental conditions; the varied relationships obtained lend more support to conceptualizations of shock-maintained behavior as exemplifying schedule-controlled behavior than to suggestions that such behavior may be readily accounted for by “safety theory.”     

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.     

Conditional discrimination learning: A critique and amplification

Carter and Werner recently reviewed the literature on conditional discrimination learning by pigeons, which consists of studies of matching-to-sample and oddity-from-sample. They also discussed three models of such learning: the “multiple-rule” model (learning of stimulus-specific relations), the “configuration” model, and the “single-rule” model (concept learning). Although their treatment of the multiple-rule model, which seems most applicable to the pigeon data, is generally excellent, their discussion of the other two models is incomplete and sometimes inaccurate. Potential problems of terminology are discussed in the present paper, as are additional lines of research that deserve consideration by those interested in further work in this area. The issue of response versus stimulus selection (configuration versus compound-cue learning) is discussed in connection with the configuration model. Particular attention is given to Carter and Werner's criticism of the application, in studies with other species, of the learning set procedure in testing for single-rule learning. Some of the important related issues are: the bias for improvement on new problems in a series, the adequacy of a multiple-rule model to explain learning set formation, and evidence in favor of the single-rule model, at least in primates. Consideration of these additional contributions to the study of conditional discrimination learning emphasizes the usefulness of this task in the comparative study of cognitive processes.     

Pigeons'' spatial memory: II. Acquisition of delayed matching of key location and transfer to new locations

Five hungry pigeons first received delayed matching of key location training. Trials began with a “ready” stimulus (brief operation of the grain feeder). Then one (randomly chosen) of a set of four keys from a three-by-three matrix was lit briefly as the sample. After a short delay (retention interval), the sample key was lit again along with one of the other eight keys. A peck at the key that had served as the sample produced grain reinforcement, whereas a peck to the other key produced only the intertrial interval. After delayed matching of key location was learned, the remaining five key locations were introduced as samples. Four of the five birds performed at considerably above-chance levels on the novel sample trials during the first as well as subsequent sessions. These results suggest that pigeons sometimes learn the single rule—“choose the location that matches the sample.” The relevance of these results to the issue of whether pigeons learn a generalized matching rule (i.e., a concept of “sameness”) is discussed.     

The role of autoshaping in cooperative two-player games between starlings

We report a study of the behavior of starlings in laboratory situations inspired by the “prisoner's dilemma.” Our purpose is to investigate some possible mechanisms for the maintenance of cooperation by reciprocity and to investigate the process of autoshaping at a trial-by-trial level. In Experiment 1, pairs of starlings housed in adjacent cages played a discrete-trial “game” in which food could be obtained only by “cooperation.” In this game, pecking at a response key eliminated the opportunity to obtain food but produced food for the partner. If neither bird pecked, neither had the opportunity to obtain food in that trial. Some level of cooperation persisted for several sessions whether the birds had been pretrained for a high or low probability of pecking at the key. The probability of a cooperative response was higher after trials in which the partner responded (and a reward was obtained) than after trials in which neither bird responded (and no reward was obtained), but the probability of a response was even higher after trials in which the same bird had responded, even though no reward was obtained by the actor in these trials. This behavior did not require visual presence of another player, because similar results were obtained in Experiment 2 (a replicate of Experiment 1 in which the members of the pair could not see each other) and in Experiment 3, a game in which each starling played with a computer responding with “tit for tat.” Using an omission schedule, in which food was given in all trials in which the bird did not peck, Experiment 4 showed that pecking could be maintained by autoshaping. In this experiment, overall probability of pecking decreased with experience, due to a drop in the tendency to peck in consecutive trials. The probability of pecking in trials following a reinforced trial did not decrease with experience. An implementation of the Rescorla–Wagner model for this situation was capable of reproducing molar, but not molecular, aspects of our results. The results violate the predictions of several game-theoretical models for the evolution of cooperation, including tit for tat, generous tit for tat, and the superior win-stay-lose-shift.