Habituation: It's not what you think it is.

In this review, we take a critical look at the methods used to document habituation and the theoretical assumptions that have been made about it. We point out problems associated with measuring habituation merely as a change over the course of repeated presentations of a stimulus. We argue that a common test procedure is essential to assess the relative magnitudes of habituation learning especially when different training procedures are examined. We further suggest that this would be required in order to draw meaningful conclusions about the conditions for optimizing habituation. We also challenge the view that habituation is nonassociative and consider the implications of various associative learning perspectives not only for context-specific habituation but for encoding a representation of the stimulus. We conclude with our recommendations for future research on habituation and we highlight the need to integrate behavioral and neurobiological studies.

Still the same in human causal reasoning: Evidence for a uniform similarity parameter in generalisation and summation.

Wagner's replaced elements model (REM) theory implies that generalisation and summation tests depend on a common similarity parameter, but few studies have assessed generalisation and summation within the same experimental paradigm. Three experiments adapted a methodology used in non-human animal studies to investigate this question in the case of human causal reasoning. The studies combined different amounts of training on simple discriminations (A+ vs. C-), compound discriminations (AB+ vs. CD-), and irrelevant novel cue discriminations (An+ vs. Cn-) with testing on single cues, compound cues, and compounds of cues with novel cues. The results were compared with predictions of Pearce's configural model and Wagner's REM elemental model. They also were examined to determine whether generalisation and summation could be accounted for using a single value for the similarity between stimulus compounds and the separable constituent cues of which the compounds were composed. The findings indicated that each theory needed to include common cues to account for the data.

Special issue to commemorate the intellectual contributions of Allan R. Wagner.

This is an introduction to the special issue "Wagner Tribute." Allan R. Wagner was the first editor in chief of this journal. It is difficult to quantitatively measure the impact that a single individual has on an entire discipline, but a brief consideration of Wagner's research output provides some insight into both the breadth of his interests and depth of his influence. Furthermore, in one way or another the many contributions to this special issue will highlight the powerful role that Wagner's empirical and theoretical work has played and continues to play in driving research into the nature of simple associative learning processes. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

On the representation of novel stimuli in patterning and irrelevant cue discriminations.

Two experiments explored ways in which novel stimuli might be represented in associative learning, focusing on (1) representations in which novel stimuli embody novelty as a stimulus feature that acquires associative strength in the same fashion as color, shape, texture, or other frequently used stimulus features; and (2) representations in which novel stimuli embody common elements, that is, the stimulus elements shared among other stimuli in an experimental setting. Both experiments examined the effects of reinforcing or nonreinforcing separately presented novel stimuli on learning about compound stimuli that included novel stimuli as part of the compound. Experiment 1 found that the relative ease of learning positive and negative patterning discriminations could be reversed, depending on whether novel stimuli were separately reinforced or nonreinforced. This result is consistent with predictions from a model that assumes novelty is a stimulus feature. Experiment 2 found that the additive effects of combining relevant and irrelevant cues in compound were not obtained when novel stimuli were used as irrelevant cues. This result is consistent with predictions from a model that assumes novel stimuli are represented as common elements. Implications for understanding how both types of representation account for the role of novelty in complex discrimination learning in general are discussed. (PsycINFO Database Record

Negative patterning and biconditional discriminations in human causal reasoning: a second look.

Harris and Livesey (2008) reported that patterning discriminations were easier to learn than biconditional discriminations in a human causal reasoning task, consistent with the predictions of the attentional buffer model of Harris (2006) and inconsistent with the predictions of configural cue models. However, their evaluation of patterning and biconditional tasks also failed to find a positive patterning advantage, which has been a hallmark prediction of many configural cue theories. This failure raises the question of whether Harris and Livesey's method was appropriate for a general evaluation of the role of configural cues in learning complex discriminations. Using a design that does produce a positive patterning advantage, the study reported here shows negative patterning discriminations to be at least as difficult to learn as biconditional discriminations, consistent with configural cue models.

A positive patterning advantage with complex but not simple patterning: a cue constellation approach.

Determinants of a positive patterning advantage (that is, an advantage for positive patterning over negative patterning) in human causal reasoning were examined in an experiment that compared simple patterning discriminations (A, B vs. AB) to complex patterning discriminations (AB, BC, AC vs. ABC). As predicted by a cue constellation analysis of complex discriminations, a positive patterning advantage was found with complex patterning but not with simple patterning discriminations. This result may explain why some recent studies have found a positive patterning advantage where earlier studies had failed to find one. The interaction of patterning complexity with the positive patterning advantage appears to pose problems for rule-based accounts of patterning. The results support the view that associative theories of human causal reasoning are more easily distinguished from rule-based approaches when applied to conditions that make simple rules difficult to identify or implement.

Effect of outcome valence on positive and negative patterning in human causal reasoning.

The importance of configural cues and whether a situation involves beneficent or maleficent outcomes was investigated in two experiments on human causal reasoning, based on experienced causal information. Participants learned positive and negative patterning discriminations involving either beneficent or maleficent outcomes in a health-reasoning task and in a social-reasoning task. With maleficent outcomes, positive patterning was consistently easier to learn than negative patterning, a positive patterning advantage that is predicted by current associative theories and commonly taken as evidence for configural cues. However, with beneficent outcomes, the two discrimination tasks were not significantly different in ease of learning, a result not predicted by current theories. The reliable positive patterning effect found with maleficent outcomes broadens the range of conditions in which the effect can be shown in causal reasoning. The novel effect of outcome valence poses an interesting theoretical challenge for attempts to account for the relation between learning about individual cues and combinations of those cues.

The experience of self in the bottlenose dolphin.

Marten and Psarakos have presented some evidence which suggests that objective self-awareness and possibly representations of self may characterize the dolphins' experience of self. Their research demonstrates the possibility of similarities in the sense of self between primate species and dolphins, although whether dolphins have subjective self-awareness, personal memories, and theories of self--all important facets of the sense of self in humans--was not examined. Clearly, even this limited evidence was difficult to achieve; the difficulties in adapting methods and coding behavior are quite apparent in their report. Future progress, however, may depend upon clarification of what are the necessary components for a sense of self and an explication of how these might be reflected in dolphin behavior. We are mindful of the authors' point (pp. 219 and 220) that the dolphin lives more in an acoustic than a visual environment. Thus, while tasks relying upon vision may reveal the presence or absence of the sense of self in primates, it might well be the case that in dolphins self-related experiences might be better revealed in auditory tasks. But then, what is the nature of human self-awareness in terms of audition? While both conceptual and methodological hurdles remain, Marten and Psarakos have demonstrated that important questions can be asked about the minds and phenomenal worlds of nonanthropoid species.

Posttrial reinstatement of the CS in Pavlovian conditioning: facilitation or impairment of acquisition as a function of individual differences in responsiveness to the CS.

Gray and Appignanesi reported that conditioning to an element of a compound conditioned stimulus (CS) was facilitated when the compound not only preceded the unconditioned stimulus (US) but was briefly reinstated shortly after US termination. The manipulation was embedded in a "blocking" design, and the effect was interpreted as being peculiar to such a situation. The present study reports five experiments, using rats in a conditioned emotional response (CER) paradigm, aimed at further evaluating the effects of CS reinstatement. In a blocking experiment patterned after that of Gray and Appignanesi, reinstatement was observed to have a decremental rather than an incremental effect on conditioned responding. In four experiments involving simple conditioning with unitary CSs, reinstatement was observed to have either an incremental or decremental effect, depending upon the subject's preconditioning responsiveness to the CSs involved. Possible mechanisms for such variable effects are discussed without obvious resolution.