J. E. R. Staddon

Transitive inference formation in pigeons

Pigeons were trained with 4 pairs of visual stimuli in a 5-term series-A+ B-, B+ C-, C+ D-. and D+ E(in which plus[+] denotes reward and minus(-] denotes nonreward)-before the unreinforced test pair B D was presented. All pigeons chose Item 8, demonstrating inferential choice. A novel theory (value transfer theory), based on reinforcement mechanisms, is proposed. In Experiment 2, the series was extended to 7 terms. Performance on test pairs was transitive, and performance on training pairs accorded with the theory. The 7-term series was closed in Experiment 3 by training the flrst and last items together. In accordance with the theory, the Ss could not solve the circular series. The authors suggest that primates, including humans, also solve these problems using the value transfer mechanism, without resorting to the symbolic processes usually assumed.

The process of recurrent choice

Recurrent choice has been studied for many years. A static law, matching, has been established, but there is no consensus on the underlying dynamic process. The authors distinguish between dynamic models in which the model state is identified with directly measurable behavioral properties (performance models) and models in which the relation between behavior and state is indirect (state models). Most popular dynamic choice models are local, performance models. The authors show that behavior in different types of discrimination-reversal experiments and in extinction is not explained by 2 versions of a popular local model and that the nonlocal cumulative-effects model is consistent with matching and that it can duplicate the major properties of recurrent choice in a set of discrimination-reversal experiments. The model can also duplicate results from several other experiments on extinction after complex discrimination training.

Interval timing: memory, not a clock.

Anticipation of periodic events signalled by a time marker, or interval timing, has been explained by a separate pacemaker-counter clock. However, recent research has added support to an older idea: that memory strength can act as a clock. The way that memory strength decreases with time can be inferred from the properties of habituation, and the underlying process also provides a unified explanation for proportional timing, the Weber-law property and several other properties of interval timing.

Autonomous search by robots and animals: A survey

This paper is a survey of research on autonomous search strategies which originate in engineering and biology. Our motivation is to identify methods of search in an essentially two-dimensional Euclidean space, which can be applied to the area of demining. Such search strategies are based on spatio-temporal distributions. These distributions may be known in advance, because of prior intelligence or through the use of remote sensing, or they may be the result of on-line gathering of information as the search progresses, or of both. We first review the literature on search and coordination which emanates from the field of robotics, we then summarize significant research in the field of animal search, and also discuss relevant results in robotics which are inspired by animal behavior.

Social learning theory and the dynamics of interaction.

The recent controversy between Bandura (1983) and Phillips and Orton (1983) about the causal relations involved in social interactions prompted a discussion of the proper role for formal models in the analysis of social interactions. I argue that (a) Banduras attempt at formal modeling of patterns of causation is vague and misleading; (b) internal variables, such as expectation and self-monitoring, can easily be handled by formal models; (c) simple deterministic models can behave in unexpectedly complex ways, so cannot be ruled out in principle as explanations for social interaction; and (d) unaided verbal reasoning cannot hope to come to grips with the dynamics of even simple interacting systems.

The Dynamics of Operant Conditioning.

Existing models of operant learning are relatively insensitive to historical properties of behavior and applicable to only limited data sets. This article proposes a minimal set of principles based on short-term and long-term memory mechanisms that can explain the major static and dynamic properties of operant behavior in both single-choice and multiresponse situations. The critical features of the theory are as follows: (a) The key property of conditioning is assessment of the degree of association between responses and reinforcement and between stimuli and reinforcement; (b) the contingent reinforcement is represented by learning expectancy, which is the combined prediction of response-reinforcement and stimulus-reinforcement associations; (c) the operant response is controlled by the interplay between facilitatory and suppressive variables that integrate differences between expected (long-term) and experienced (short-term) events; and (d) very-long-term effects are encoded by a consolidated memory that is sensitive to the entire reinforcement history. The model predicts the major qualitative features of operant phenomena and then suggests an experimental test of theoretical predictions about the joint effects of reinforcement probability and amount of training on operant choice. We hypothesize that the set of elementary principles that we propose may help resolve the long-standing debate about the fundamental variables controlling operant conditioning.

Probabilistic choice: A simple invariance.

When subjects must choose repeatedly between two or more alternatives, each of which dispenses reward on a probabilistic basis (two-armed bandit ), their behavior is guided by the two possible outcomes, reward and nonreward. The simplest stochastic choice rule is that the probability of choosing an alternative increases following a reward and decreases following a nonreward (reward following ). We show experimentally and theoretically that animal subjects behave as if the absolute magnitudes of the changes in choice probability caused by reward and nonreward do not depend on the response which produced the reward or nonreward (source independence ), and that the effects of reward and nonreward are in constant ratio under fixed conditions (effect-ratio invariance )--properties that fit the definition of satisficing . Our experimental results are either not predicted by, or are inconsistent with, other theories of free-operant choice such as Bush-Mosteller, molar maximization, momentary maximizing, and melioration (matching).

An effect analogous to “frustration” on interval reinforcement schedules

There are similarities between pigeons’ behavior under interval reinforcement schedules and the behavior of rats in runways. A free-operant experiment analogous in certain respects to the double-runway procedure produced large “frustration effects” in pigeons, lending support to this comparison.

Dynamics of time discrimination.

Pigeons tracked sinusoidal sequences of interfood intervals (IFIs) by pausing in each interval for a time proportional to the preceding interval. Schedules with either long (30-90 s) or short (5-15 s) values, with variable numbers of cycles and starting phase each day, were tracked about equally well. Tracking was apparently immediate and did not improve across sessions. Experiment 2, in which long and short series were presented on alternate days, showed that tracking on long was more impaired than on short. Experiment 3 showed that occasional presentation of a short IFI in a series of fixed, longer IFIs caused a reduction in waiting time in the next IFI. These effects are evidence for a fast-acting timing mechanism in which waiting time in the IFI N + 1 is strongly determined by the preceding IFI, N. Earlier IFIs have some cumulative effect, but the details remain to be elucidated.

An experimental investigation of the bioacoustics of cowbird song

SummaryFemale cowbirds (Molothrus ater ater), maintained in isolation from males during the breeding season, respond to the playback of male song with copulatory postures. They respond to some songs more than to others. Cowbird song potency can thus be operationally defined by the proportion of copulatory postures a song elicits across multiple playbacks. The purpose of the present study was to explore whether song potency changes with distance in the field. No field recordings elicited high levels of responding by the females. When songs of known high potency are systematically degraded, the results indicate that female cowbirds are sensitive to small changes in signal to noise ratio and to atmospheric attenuation. The data suggest that cowbird song potency degrades very rapidly with transmission distance in the field.