Limulus psychophysics: Increment threshold

Prior temporal summation work had indicated that the sensory code for certain behaviors (in bothLimulus and humans) can be understood if one suggests that the central nervous system analyzes the integral of the photoreceptor potential. An independent test of this suggestion is available because (inLimulus) the physiological increment threshold function obtained from the receptor potential integral is inflected, whereas that obtained from the initial transient peak of the receptor potential is not. The behavioral increment threshold function was measured inLimulus and found to be inflected. Fechner’s scaling assumption (that equally detectable stimulus increments are mediated by sensory signals of equal size) was supported by the fact that a theoretical function, which was calculated from the receptor integral intensity-response function by using Fechner’s scaling assumption, was able to fit the behavioral increment threshold function quite well. Furthermore, the variability of the behavioral data was proportional to the receptor integral variability. A seasonal effect was observed: Fall animals were more sensitive and had a higher criterion than winter animals. These findings permit the specification of the rerceptor potential that mediates this particular behavior at threshold: It has a steady-state amplitude of 7 mV in winter and 16 mV in fall. Taken in conjunction with the results of earlier temporal summation work indicating that the threshold receptor potential is 4.5 sec long, this specification implies that at least some behaviors are mediated by large, long sensory signals, which have properties very different from those of small, short signals, particularly with regard to both linearity and their relative dependence on time vs. energy.     

Stimulus selection in passive avoidance learning and retention: weanling, periadolescent, and young adult rats

Periadolescent rats exhibit a number of behavioral differences in comparison with younger or older animals. For instance, periadolescents tend to show enhanced acquisition of simple active avoidance tasks, but impaired acquisition of more complex appetitive and aversive discriminations. In this experiment, rats were trained on a simple passive avoidance task at one of three ages, as weanlings (25 days), periadolescents (35 days), or young adults (45 days). Training occurred in the presence of both a redundant discriminative stimulus and a specified, redundant contextual stimulus. The periadolescents did not differ from either younger or older rats in rate of learning the passive avoidance task. The retention performance of these animals was then tested following a change in either, neither, or both of the redundant cues. When a measure of performance that controls for baseline activity was used, it was observed that periadolescents were not disrupted by a change in the redundant discriminative stimulus, a cue change that clearly disrupted performance in 25- and 45-day-old animals, and tended to be more disrupted by the contextual change than younger or older rats. It is hypothesized that the alterations in performance exhibited by periadolescents may be related to an ontogenetic alteration in stimulus selection modulated by the catecholaminergic systems.     

Visual processing for action resists similarity of relevant and irrelevant object features

It has been suggested that the human brain processes visual information in different manners, depending on whether the information is used for perception or for action control. This distinction has been criticized for the lack of behavioral dissociations that unambiguously support the proposed two-visual-pathways model. Here we present a new and simple dissociation between vision for perception and vision for action: Perceptual judgments are affected by the similarity of relevant and irrelevant stimulus features, while object-oriented actions are not. This dissociation overcomes the methodological problems of previously proposed differences in terms of vulnerability to visual illusions or to variability in irrelevant object features, and it can also serve as an easily applicable behavioral indicator of underlying processing modes.     

Human latent inhibition: Problems with the stimulus exposure effect

Latent inhibition (LI) is a startlingly simple effect in which preexposure of a stimulus without consequence retards subsequent responding to a stimulus–consequence relation. The effect was first demonstrated with Pavlovian conditioning in animals and was later suggested to be a marker of human psychopathology such as schizophrenia. Individual differences in LI has supported the continued use of animal models to understand human mental health. In this review, we ask whether there is sufficient evidence to support the continued application of LI from animal models to human psychopathology because of the weak evidence for LI in humans. There is considerable variability in the methods used to assess LI, sustaining different theoretical accounts of the effects observed, which differ from the accepted accounts of LI as demonstrated in animals. The review shows that although there have been many experiments testing human LI, none provide the necessary experimental controls to support the conclusion that retarded responding is caused simply by preexposure to a stimulus, as has been demonstrated with animal models. Establishing this conflict, we set out a framework for future research.     

Contrast and the justification of effort

When humans are asked to evaluate rewards or outcomes that follow unpleasant (e.g., high-effort) events, they often assign higher value to that reward. This phenomenon has been referred to ascognitive dissonance or justification of effort. There is now evidence that a similar phenomenon can be found in nonhuman animals. When demonstrated in animals, however, it has been attributed to contrast between the unpleasant high effort and the conditioned stimulus for food. In the present experiment, we asked whether an analogous effect could be found in humans under conditions similar to those found in animals. Adult humans were trained to discriminate between shapes that followed a high-effort versus a low-effort response. In test, participants were found to prefer shapes that followed the high-effort response in training. These results suggest the possibility that contrast effects of the sort extensively studied in animals may play a role in cognitive dissonance and other related phenomena in humans.     

Action blindness in response to gradual changes

The goal of this study is to characterize observers’ abilities to detect gradual changes and to explore putative dissociations between conscious experience of change and behavioral adaptation to a changing stimulus. We developed a new experimental paradigm in which, on each trial, participants were shown a dot pattern on the screen. Next, the pattern disappeared and participants had to reproduce it. In some conditions, the target pattern was incrementally rotated over successive trials and participants were either informed or not of this change. We analyzed both awareness of the changes and the dynamics of behavioral adaptation, in a way that makes it possible to assess both variability and accuracy as they change over time. Results indicate a dissociation between change awareness and behavioral adaptation to the changes, and support the notion that unconscious representations of visual stimuli are more precise and detailed than previously suggested. We discuss the implications of these results for theories of change detection.     

Hippocampal electrical activity and behavior in rabbits living in a seminatural environment: reactions in the presence of a dog

The aim of the present experiment was to correlate behavioral and electrical events recorded in the presence of a threatening stimulus, namely a dog presented to rabbits living in a seminatural environment. Behavioral and concomitant EEG, recorded by telemetry, were studied in rabbits carrying chronic electrodes implanted in the hippocampus, before, during, and after the introduction of a dog into the environment around the enclosure. The threatening stimulus caused a variety of emotional responses in the rabbits, associated with high rhythmicity and high frequency levels in the hippocampal EEG. After removal of the dog the state of alarm of the animals persisted with long periods of alert immobility characterized by a further increase in hippocampal EEG frequency. Data show that emotional and environmental aspects can affect the hippocampal electrical activity recorded during specific behavioral elements.     

Theoretical and methodological considerations for the study of imagery in animals

Transformation of a moving stimulus is an operational definition of imagery that is useful in animal research. This definition was developed from structural, functional, and interactive theories of imagery in humans. The historical roots of the definition are traced to behavioristic methodologies within cognitive psychology. An imagery procedure for animals was developed that tests this definition with extrapolated movement. Pigeons were reinforced for discriminating between a rectangle that rotated at constant velocity from a rectangle whose final location violated constant velocity. Imagery trials included a short-term memory component in which the task of the pigeon was to discriminate between extrapolated trajectories of rotation while the rectangle was absent. The evidence supports similarities between human and animal representations of movement. A visible transformation employed as a sample stimulus and followed by a retention interval provides a powerful procedure for measuring the interaction between perception and memory. An advantage of this paradigm is that it could be employed to investigate imagery at the neural level or to obtain comparative behavioral data from different species.     

On the origins of naming and other symbolic behavior

We identify naming as the basic unit of verbal behavior, describe the conditions under which it is learned, and outline its crucial role in the development of stimulus classes and, hence, of symbolic behavior. Drawing upon B. F. Skinner's functional analysis and the theoretical work of G. H. Mead and L. S. Vygotsky, we chart how a child, through learning listener behavior and then echoic responding, learns bidirectional relations between classes of objects or events and his or her own speaker-listener behavior, thus acquiring naming-a higher order behavioral relation. Once established, the bidirectionality incorporated in naming extends across behavior classes such as those identified by Skinner as the mand, tact, and intraverbal so that each becomes a variant of the name relation. We indicate how our account informs the specification of rule-governed behavior and provides the basis for an experimental analysis of symbolic behavior. Furthermore, because naming is both evoked by, and itself evokes, classes of events it brings about new or emergent behavior such as that reported in studies of stimulus equivalence. This account is supported by data from a wide range of match-to-sample studies that also provide evidence that stimulus equivalence in humans is not a unitary phenomenon but the outcome of a number of different types of naming behavior.     

Discrimination and categorization of actions by pigeons

Recognizing and categorizing behavior is essential for animals (e.g., during mate selection, courtship, and avoidance of predators). In a study examining if and how animals classify different actions, a go/no-go procedure was used to train 4 pigeons to discriminate among "walking" and "running" digital animal models (each portrayed from 12 different viewpoints). Action discrimination acquired for two models significantly transferred to six novel animal models moving in novel and biomechanically characteristic ways. Randomization of frame order in the animated sequences, stimulus inversion, and static presentation all disrupted this discrimination, whereas changes in the direction and speed (both increases and decreases) of the actions did not. These results suggest that the pigeons discriminated the behaviors on the basis of generalized recognition of the models' sequence of poses across time and provide the best evidence yet that animals use action categories to identify contrasting behavioral units.     

Animals may not be stuck in time

Humans have the ability to mentally travel forward and back in time. They can retrieve vivid memories of past events (episodic memories) and can imagine the future (planning). Although it has been suggested that this is a uniquely human ability, the evidence for subjective time travel in humans is typically based on verbal report and elaboration. Such evidence cannot be obtained from animals. However, we may have indirect evidence for episodic memory and planning. For example, we can show that animals can ‘report’ about their recent past experience when they are unexpectedly asked to do so—performance that is analogous to episodic memory. We can also show that animals use the anticipation of a future event as the basis for a present action—analogous to planning. Thus, we have suggestive evidence that animals may not be stuck in time.     

Some considerations about the biological appearance of pacing stimuli in visuomotor finger-tapping tasks

Sensorimotor synchronization is a crucial function for human daily activities, which relies on the ability of predicting external events. Synchronization performance, as assessed in finger-tapping (FT) tasks, is characterized by an anticipation tendency, as the tap generally precedes the pacing event. This synchronization error (SE) depends on many factors, in particular on the features of the pacing stimulus. Interest is growing in the facilitation effect that action observation has on motor execution. So far, neuroimaging and neurophysiology studies of motor priming via action observation have mainly employed tasks requiring single action instances. The impact of action observation on motor synchronization to periodic stimuli has not yet been tested; to this aim, a synchronization FT task may be an eligible probing task. The purpose of this study was to characterize a biological pacer at the behavioral level and provide information for those interested in studying the brain processes of continuous observation/execution coupling in timed actions using FT tasks. We evaluated the influence of the biological appearance of a pacer (a tapping finger) on SE, when compared to an abstract, kinematically equivalent pacer (a tilting hinged bar) and a more standard stimulus (a pulsating dot). We showed that the continuous visual display of a biological pacer yields comparable results to the abstract pacer, and a more robust performance and larger anticipations than a traditional pulsating stimulus.     

TOKEN REINFORCEMENT: A REVIEW AND ANALYSIS

Token reinforcement procedures and concepts are reviewed and discussed in relation to general principles of behavior. The paper is divided into four main parts. Part I reviews and discusses previous research on token systems in relation to common behavioral functions—reinforcement, temporal organization, antecedent stimulus functions, and aversive control—emphasizing both the continuities with other contingencies and the distinctive features of token systems. Part II describes the role of token procedures in the symmetrical law of effect, the view that reinforcers (gains) and punishers (losses) can be measured in conceptually analogous terms. Part III considers the utility of token reinforcement procedures in cross‐species analysis of behavior more generally, showing how token procedures can be used to bridge the methodological gulf separating research with humans from that with other animals. Part IV discusses the relevance of token systems to the field of behavioral economics. Token systems have the potential to significantly advance research and theory in behavioral economics, permitting both a more refined analysis of the costs and benefits underlying standard economic models, and a common currency more akin to human monetary systems. Some implications for applied research and for broader theoretical integration across disciplines will also be considered.     

Using robots to understand animal cognition

In recent years, robotic animals and humans have been used to answer a variety of questions related to behavior. In the case of animal behavior, these efforts have largely been in the field of behavioral ecology. They have proved to be a useful tool for this enterprise as they allow the presentation of naturalistic social stimuli whilst providing the experimenter with full control of the stimulus. In interactive experiments, the behavior of robots can be controlled in a manner that is impossible with real animals, making them ideal instruments for the study of social stimuli in animals. This paper provides an overview of the current state of the field and considers the impact that the use of robots could have on fundamental questions related to comparative psychology: namely, perception, spatial cognition, social cognition, and early cognitive development. We make the case that the use of robots to investigate these key areas could have an important impact on the field of animal cognition.     

Behavioral variability as avoidance behavior

This study aimed to investigate whether variable patterns of responses can be acquired and maintained by negative reinforcement under an avoidance contingency. Six male Wistar rats were exposed to sessions in which behavioral variability was reinforced according to a Lag contingency: Sequences of three responses on two levers had to differ from one, two or three previous sequences for shocks to be avoided (Lag 1, Lag 2 and Lag 3, respectively). Performance under the Lag conditions was compared with performance on a Yoke condition in which the animals received the same reinforcement frequency and distribution as in the Lag condition but behavioral variability was not required. The results showed that most of the subjects varied their sequences under the Lag contingencies, avoiding shocks with relatively high probability (≥ 0.7). Under the Yoke procedure, responding continued to occur with high probability, but the behavioral variability decreased. These results suggest that behavioral variability can be negatively reinforced.     

Today I'll use a condom, but who knows about tomorrow: a daily process study of variability in predictors of condom use

OBJECTIVE: Most models of health behavior change applied to condom use behavior have focused on individual differences in theoretical constructs to explain condom use or nonuse, while ignoring the possibility that day-to-day within-person changes in these constructs may contribute to understanding behavior. The goal of the present study was to investigate day-to-day variability in condom use attitudes, self-efficacy, and behavioral intentions and assess the utility of this variability in predicting the likelihood of condom use each day. DESIGN: A 30-day Web-based structured daily diary was used to collect daily reports of sexual behaviors and data on theoretical predictors of condom use behavior from sexually active college students (N = 116). MAIN OUTCOME MEASURES: The authors investigated whether condom use attitudes, self-efficacy, and behavioral intentions vary day to day; whether this within-person variability predicts condom use behavior; and whether negative affective states explain this variability. RESULTS AND CONCLUSIONS: Within-person variability was found for each of the constructs. Within-person day-to-day changes in behavioral intentions and attitudes predicted the instances in which an individual used a condom and daily negative affect partially explained within-person day-to-day changes in behavioral intentions and self-efficacy. Implications for models of health behavior change and for behavior change interventions are discussed.     

HUMAN MODELS OF ANIMAL BEHAVIOR

Abstract— Similarities between the behavior of humans and other animals in analogous tasks suggest that similar cognitive processes are involved. Human studies provide an efficient way to collect data with low variability, and animal studies provide a way to collect a large amount of data under controlled conditions, study a wide range of manipulations, limit the range of plausible explanations, and develop explanations in terms of brain mechanisms. Examples are taken from studies of liming that used similar procedures for humans and other animals.     

The relation between action, predictability and temporal contiguity in temporal binding

Previous studies have documented a subjective temporal attraction between actions and their effects. This finding, named intentional binding, is thought to be the result of a cognitive function that links actions to their consequences. Although several studies have tried to outline the necessary and sufficient conditions for intentional binding, a quantitative comparison between the roles of temporal contiguity, predictability and voluntary action and the evaluation of their interactions is difficult due to the high variability of the temporal binding measurements. In the present study, we used a novel methodology to investigate the properties of intentional binding. Subjects judged whether an auditory stimulus, which could either be triggered by a voluntary finger lift or be presented after a visual temporal marker unrelated to any action, was presented synchronously with a reference stimulus. In three experiments, the predictability, the interval between action and consequence and the presence of action itself were manipulated. The results indicate that (1) action is a necessary condition for temporal binding; (2) a fixed interval between the two events is not sufficient to cause the effect and (3) only in the presence of voluntary action do temporal predictability and contiguity play a significant role in modulating the effect.These findings are discussed in the context of the relationship between intentional binding and temporal expectation.     

The simultaneous chain: a new approach to serial learning

Recent advances have allowed the application of behaviorism's rigor to the control of complex cognitive tasks in animals. This article examines recent research on serially organized behavior in animals. 'Chaining theory', the traditional approach to the study of such behavior, reduces intelligent action to sequences of discrete stimulus-response units in which each overt response is evoked by a particular stimulus. However, such theories are too weak to explain many forms of serially organized cognition, both in humans and animals. By training non-human primates to produce arbitrary sequences that cannot be learned as chains of particular motor responses, the simultaneous chaining paradigm has overcome limitations of chaining theory in experiments on serial expertise, the use of numerical rules, knowledge of ordinal position, and distance and magnitude effects.     

A convective thermal controller for behavioral experiments

The Convective Thermal Controller (CTC) is designed to provide rapid and precise control of a thermal stimulus for application to behavioral experiments with small animals. Subjects are bathed in one of two continuously recirculating air systems; two valves determine which of the systems play on S. When the systems are stabilized at different temperatures, actuation of the valves can produce an abrupt and stable temperature change in .3 sec. Behavioral observations indicate that escape learning occurs readily; latency decreases monotonically with drive intensity and increases monotonically with reinforcement duration.