The Quarterly journal of experimental psychology. B, Comparative and physiological psychology最新文献

Two experiments investigated the effects of similarity between intertrial interval (ITI) and delay illumation on the choose-short effect. Different groups of pigeons learned to match "short" (2 s) and "long" (6 or 8 s) food samples to green and red test stimuli in a matching-to-sample procedure with a 5-s training delay. Subsequent 10- and 20-s delay tests revealed choose-short effects if the ITI and delay were both illuminated (i.e., group ON-ON), if the ITI and delay were both dark (i.e., group OFF-OFF), and if the ITI was illuminated and the delay was dark (i.e., group ON-OFF). In addition, either a choose-short effect or a choose-long effect was observed if the ITI was dark and the delay was illuminated (i.e., group OFF-ON). Results are incompatible with the confusion/instructional failure view of the choose-short effect.

Recently (Troje, Huber, Loidolt, Aust, & Fieder 1999), we found that pigeons discriminated between large sets of photorealistic frontal images of human faces on the basis of sex. This ability was predominantly based on information contained in the visual texture of those images rather than in their configural properties. The pigeons could learn the distinction even when differences of shape and average intensity were completely removed. Here, we proved more specifically the pigeons' flexibility and efficiency to utilize the class-distinguishing information contained in complex natural classes. First, we used principal component as well as discriminant function analysis in order to determine which aspects of the male and female images could support successful categorization. We then conducted various tests involving systematic transformations and reduction of the feature content to examine whether or not the pigeons' categorization behaviour comes under the control of category-level feature dimensions--that is, those stimulus aspects that most accurately divide the stimulus classes into the experimenter-defined categories of "Male" and "Female". Enhanced classification ability in the presence of impoverished test faces that varied only along one of the first three principal components provided evidence that the pigeons used these class-distinguishing stimulus aspects as a basis for generalization to new instances.

Three experiments examined conditioned magazine approach in rats when a positive unconditioned stimulus (US) bore a random relation to a conditioned stimulus (CS). Experiment 1 found that over the course of conditioning the CS initially elevated responding relative to the baseline but then lost the power to do so. Transfer tests revealed that a CS-US association developed early and persisted despite the decline in magazine responding. Experiment 2 confirmed the persistence of CS-US associations and found them to be more substantial when a different US occurred during the CS than in its absence. In Experiment 3, when the situation was exposed to US-alone presentations prior to introducing the CS, there was little evidence that a subsequent random relation between the CS and US produced an association between them. These results agree with those of blocking and overshadowing experiments using discrete CSs and support an interpretation of the random procedure in terms of competition between the background and CS for conditioning.

In the present study, sensory preconditioning of human electrodermal activity was demonstrated. In the first phase of the experiment, two pairs of neutral pictures of human faces were presented (A/B and C/D) sequentially. In the second phase, one picture of one pair was immediately followed by an electrocutaneous stimulus (B+), and one picture of the other pair was not (D-). In the third phase the other picture of each pair (A and C) was tested. The effect of A and C alone presentations (pre-extinction) between the first and the second phase was investigated. When only those participants that showed reliable B+/D- differentiation were considered, the extinction group did not show stronger conditioned electrodermal activity to A than to C, whereas the control group did. These findings suggest that sensory preconditioning of anticipatory/preparatory responding only occurs when the pre-conditioned stimulus (A) actually predicts the conditioned stimulus (B).

In Experiments 1 and 2, lever pressing by rats was reinforced on a cyclic ratio schedule of food reinforcement, comprising a repeated sequence of fixed-ratio component schedules. Reinforcement magnitude was varied, on occasional sessions in Experiment 1 and across blocks of sessions in Experiment 2, from one to two or three 45-mg food pellets. In the one-pellet condition, post-reinforcement pauses increased with component schedule value. At higher magnitudes, post-reinforcement pauses increased, and overall response rates declined. Response rate on component schedules was a decreasing linear function of the obtained rate of reinforcement in all conditions. Plotted against component schedule value, response rate increased exponentially to an asymptote that decreased when reinforcement magnitude increased. These findings are consistent with regulatory accounts of food-reinforced behaviour. In Experiment 3, rats were trained under a cyclic ratio schedule comprising fixed-ratio components including higher values, and some inverted U-shaped response functions were obtained. Those rats that did not show this relationship were trained on cyclic ratios with even higher values, and all showed inverted U-shaped response functions. This suggests that behaviour on cyclic ratio schedules can reflect activating of reinforcement as well as the satiating effects seen in Experiments 1 and 2.

The 5-hydroxytryptamine1a (5-HT1a) receptor agonist 8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT; 0.15 mg/kg) impaired rats' rapid visual learning on a computerized maze. This treatment also increased decision time (DT) but the learning impairment was not necessarily a side-effect of slower responding because, in this task, responses made at long DT are more accurate than those at short DT. The selective 5-HT1a receptor antagonist WAY-100635 (0.3 mg/kg) was itself without effect on accuracy, but was effective in reversing effects of 8-OH-DPAT (on both accuracy and DT). Within problems (i.e., over the 40-60 trials of a single discrimination), performance was reduced by treatment with 8-OH-DPAT at all stages of learning. We conclude that this effect is mediated through the 5-HT1a receptor site (rather than through some other serotonergic receptor site or non-specific mechanism) as it was reversible by treatment with WAY-100635. Although it could still arise from behaviourally non-specific effects, the performance deficit finds its best account in terms of the psychological processes necessary to visual learning. Its reversal with WAY-100635 offers support to the hypothesis that 5-HT1a receptor antagonists could improve cognitive function, under conditions of pre-existing impairment due to overactive serotonergic inhibition, as is thought to occur in Alzheimer's disease.

Three Pavlovian conditioning experiments with human participants are reported, which investigated whether common or separate stimulus representations are involved in solving nonlinear discrimination tasks in different response systems. In our experiments we made use of a negative transfer effect between positive and negative patterning. Experiment 1 specified the conditions under which such a negative transfer effect occurs in human eyelid conditioning. Experiments 2 and 3 investigated whether a similar effect also occurs if two response systems--the eyelid and the skin conductance response system--are trained with trials of both types being randomly interleaved. The presence or absence of a negative transfer effect indicates whether or not the stimulus representations involved in the two conditioning processes overlap. The findings are discussed within the framework of a neuropsychological model of hippocampal function. The results suggest that the representations are distinct and thus support the idea of acquired equivalence and distinctiveness of stimulus representations.

In three experiments, rats were pre-exposed either to uncorrelated presentations of a light and sucrose pellets (group CS/US) or to equivalent presentations of the light and pellets in separate sessions (control). In Experiment 1, subsequent conditioning to the light proceeded more slowly in group CS/US than in the control group, whether this conditioning was excitatory, with the light signalling the delivery of pellets, or inhibitory, with the light signalling their absence. Bonardi and Hall (1996) have argued that this learned irrelevance effect may be reducible to latent inhibition, which would be stronger in group CS/US because they are both pre-exposed and conditioned to the CS in the presence of traces of previous USs occurring in the same session. This analysis implies that group CS/US should have conditioned more rapidly to the CS than controls on the first trial of each session in Experiment 1, but this did not happen. It also implies that the learned irrelevance effect should be reversed if conditioning trials are given at a rate of one per day. Experiments 2 and 3 found no support for this prediction. We conclude that learned irrelevance effects cannot always be reduced to latent inhibition.

According to the comparator process hypothesis (Matute, Arcediano, & Miller, 1996), cue competition in the learning of between-events relationships arises if the judgement required involves a comparison between the probability of the outcome given the target cue and the probability of the outcome given the competing cue. Alternatively, other associative accounts (the Rescorla-Wagner model: Rescorla & Wagner, 1972) conceive cue competition as a learning deficit affecting the target cue-outcome association. Consequently, the comparator process hypothesis predicts that cue competition occurs in inference judgements but not in contiguity ones, for only the first type of judgement implicitly involves such a comparison. On the other hand, the Rescorla-Wagner model predicts cue competition in both inference and contiguity judgements, because it establishes no relevant role for the type of judgement in producing cue competition. In Experiments 1 and 2 we manipulated the relative validity of cues and the type of question (inference vs. contiguity) in a predictive learning task. In both experiments we found a cue competition effect, but no interaction between the relative validity of cues and the type of question, suggesting that the Rescorla-Wagner theory suffices to explain cue competition.