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In an experiment involving a new behavioural preparation the role played by similarity in discrimination learning was examined using visual patterns (i.e., paintings) that might share common elements (specifically, A, BC, and ABC). A-C were small stars of three specific colours (target colours), which were intermixed with other stars of two different colours (distracting colours). The target colours were balanced through A-C. Students received discrimination training in which a fictitious painter was the author of paintings A and BC, while paintings ABC were assigned to a second fictitious painter. During training, the students had to make a choice, in the presence of each pattern, between two response keys, each of them indicating one of the painters. The time taken to respond was also measured. Feedback was always given after each key-press. The results showed that while at times the A+ ABC- discrimination was acquired more readily than was the BC+ ABC- discrimination, on other occasions the reverse was also true, the critical factor being the way in which the colours were combined.
The mushroom bodies of the insect brain play an important role in olfactory processing, associative learning and memory. The mushroom bodies show odor-specific spatial patterns of activity and are also influenced by visual stimuli.
Functional imaging was used to investigate changes in the in vivo responses of the mushroom body of the hawkmoth Manduca sexta during multimodal discrimination training. A visual and an odour stimulus were presented either together or individually. Initially, mushroom body activation patterns were identical to the odour stimulus and the multimodal stimulus. After training, however, the mushroom body response to the rewarded multimodal stimulus was significantly lower than the response to the unrewarded unimodal odour stimulus, indicating that the coding of the stimuli had changed as a result of training. The opposite pattern was seen when only the unimodal odour stimulus was rewarded. In this case, the mushroom body was more strongly activated by the multimodal stimuli after training. When no stimuli were rewarded, the mushroom body activity decreased for both the multimodal and unimodal odour stimuli. There was no measurable response to the unimodal visual stimulus in any of the experiments. These results can be explained using a connectionist model where the mushroom body is assumed to be excited by olfactory stimulus components, and suppressed by multimodal configurations.
Discrimination training with multimodal stimuli consisting of visual and odour cues leads to stimulus specific changes in the in vivo responses of the mushroom body of the hawkmoth.
Over the last few years, research on learning and memory has become increasingly interdisciplinary. In the past, theories of learning, as a prerogative of psychologists, were generally formulated in purely verbal terms and evaluated exclusively at the behavioral level. At present, scientists are trying to build theories with a quantitative and biological flavor, seeking to embrace more complex behavioral phenomena. Pavlovian conditioning, one of the simplest and ubiquitous forms of learning, is especially suited for this multiple level analysis (i.e., quantitative, neurobiological, and behavioral), in part because of recent discoveries showing a correspondence between behavioral phenomena and associative properties at the cellular and systems levels, and in part because of its well established quantitative theoretical tradition. The present review, examines the mayor quantitative theories of Pavlovian conditioning and the phenomena to which they have been designed to account. In order to provide researchers from different disciplines with a simple guideline about the rationale of the different theoretical choices, all the models are described through a single formalism based on the neural network connectionist perspective.
Rats were trained on an elevated maze where the rewarded alternative was
defined either in terms of intra-maze or in terms of extra-maze cues. Preexposure
to these cues produced a small latent or perceptual learning effect, i.e.
facilitated subsequent learning of both problems, by comparison with animals
pre-exposed to the maze with no cues present. Experiment 2 examined whether
the effect of pre-exposure on intra-maze discrimination learning varied with the
nature of the intra-maze cues. When positive and negative arms were further
differentiated by painting the walls white and black, a marginal perceptual
learning effect was turned into significant latent inhibition, i.e. a retardation of
subsequent learning. Pre-exposure thus reliably facilitated extra-maze discrimination
learning, and its beneficial effects on intra-maze discrimination could be
reversed by reducing the overlap between the intra-maze cues. Perceptual
learning may therefore depend on requiring animals to discriminate between
stimuli containing many common elements.
Review of the literature indicates that, according to theories of selective attention, learning about a stimulus depends on attending to that stimulus; this is represented in 2-stage models by saying that Ss switch in analyzers as well as learning stimulus-response associations. It is argued that this assumption, however, is equally well represented in a formal model by the incorporation of a stimulus-specific learning-rate parameter, a, into the equations describing changes in the associative strength of stimuli. Previous theories of selective attention have also assumed that (a) Ss learn to attend to and ignore relevant and irrelevant stimuli (i.e., that a may increase or decrease depending on the correlation of a stimulus with reinforcement); and (b) there is an inverse relationship between the probabilities of attending to different stimuli (i.e., that an increase in a to one stimulus is accompanied by a decrease in a to others). The first assumption has been used to explain the phenomena of acquired distinctiveness and dimensional transfer, the second to explain those of overshadowing and blocking. It is argued that although the first assumption is justified by the data, the second is not: Overshadowing and blocking are better explained by the choice of an appropriate rule for changing a, such that a decreases to stimuli that signal no change from the probability of reinforcement predicted by other stimuli. (65 ref) (PsycINFO Database Record (c) 2012 APA, all rights reserved)
Trained 6 male albino New Zealand rabbits in classical eyelid discrimination involving negative patterning, i.e., reinforced presentation of 2 isolable cues, A+ and B+, and nonreinforced presentation of their compound, AB-. The basis for discriminative responding which was thereby produced was evaluated by additionally reinforcing a 1/3 single cue, C+, and testing responding to novel compounds AC and BC as well as to AB, A, B, and C. Although there was less responding to the nonreinforced compound than to any single cues, there was significantly more responding to the novel compounds, AC and BC. Results show that component response strengths summate to determine compound responding, but that there are functional, configurational components relatively unique to a stimulus compound. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
In two experiments, we examined two related conditioning problems previously investigated by Red-head and Pearce (1995a) and
Pearce, Aydin, and Redhead (1997). Experiment 1 involved an A+, B+, C+, AB+, AC+, BC+, ABC2 discrimination. The Rescorla-Wagner
model predicts that response to AB, AC, and BC will be greater than that to A, B, and C at asymptote, whereas the Pearce model
makes the opposite prediction. In Experiment 2, we investigated the responding to a novel ABC compound in groups trained with
either A+, B+, C+ or AB+, AC+, BC+. The Rescorla-Wagner model predicts greater response to ABC in the group trained with A+,
B+, C+ than in the group trained with AB+, AC+, BC+, whereas the Pearce model makes the opposite prediction. In contrast to
the findings of Redhead and Pearce (1995a) and Pearce et al. (1997) in pigeon autoshaping, our findings in rabbit eyelid conditioning
support the Rescorla-Wagner model.
My theories of associative learning, like those of N. J. Mackintosh and almost all learning theorists, have employed elemental representations of the stimuli involved. We must take notice when two important contributors to elemental theory, J. M. Pearce and W. K. Estes, find sufficient problems with the theory type to cause them to defect from it. I will describe some of the essential problems, concerning the substantial influence of context on learning and retrieval, characterize the different responses of Pearce and Estes, and, then, propose a variation on a recently developed elemental model that was similarly inspired. The resulting elemental theory has a close quantitative relationship to the product-rule of Estes and D. L. Medin, and may help us to rationalize how the same formal experimental design can sometimes produce results that favour the configural interpretation of Pearce and at other times the elemental interpretation of R. A. Rescorla and A. R. Wagner, as these have often been pitted against each other.
This research focuses on the relation between color and psychological functioning, specifically, that between red and performance attainment. Red is hypothesized to impair performance on achievement tasks, because red is associated with the danger of failure in achievement contexts and evokes avoidance motivation. Four experiments demonstrate that the brief perception of red prior to an important test (e.g., an IQ test) impairs performance, and this effect appears to take place outside of participants' conscious awareness. Two further experiments establish the link between red and avoidance motivation as indicated by behavioral (i.e., task choice) and psychophysiological (i.e., cortical activation) measures. The findings suggest that care must be taken in how red is used in achievement contexts and illustrate how color can act as a subtle environmental cue that has important influences on behavior.
Human contingency learning was used to compare the predictions of configural and elemental theories. In three experiments, participants were required to learn which indicators were associated with an increase in core temperature of a fictitious nuclear plant. Experiments 1 and 2 investigated the rate at which a triple-element stimulus (ABC) could be discriminated from either single-element stimuli (A, B, and C) or double-element stimuli (AB, BC, and AC). Experiment 1 used visual stimuli, whilst Experiment 2 used visual, auditory, and tactile stimuli. In both experiments the participants took longer to discriminate the triple-element stimulus from the more similar double-element stimuli than from the less similar single-element stimuli. Experiment 3 tested for summation with stimuli from either a single or multiple modalities, and summation was found only in the latter case. Thus, the pattern of results seen in Experiments 1 and 2 was not dependent on whether the stimuli were single modal or multimodal, nor was it dependent on whether the stimuli could elicit summation. This pattern of results is consistent with predictions derived from Pearce's (1987, 1994) configural theory.
The evolution of trichromatic color vision in primates may improve foraging performance as well as intraspecific communication; however, the context in which color vision initially evolved is unknown. We statistically examined the hypothesis that trichromatic color vision in primates represents a preexisting bias for the evolution of red coloration (pelage and/or skin) through sexual selection. Our analyses show that trichromatic color vision evolved before red pelage and red skin, as well as before gregarious mating systems that would promote sexual selection for visual traits and other forms of intraspecific communication via red traits. We also determined that both red pelage and red skin were more likely to evolve in the presence of color vision and mating systems that promote sexual selection. These results provide statistical support for the hypothesis that trichromatic color vision in primates evolved in a context other than intraspecific communication with red traits, most likely foraging performance, but, once evolved, represented a preexisting bias that promoted the evolution of red traits through sexual selection.
The role played by similarity in discrimination learning was examined in four experiments using compound stimuli. In Experiment 1, pigeons received training in which food was presented after stimulus A, compound AB, but not compound ABC—A+ BC+ ABCo. The A+ ABCo discrimination was acquired more readily than was the BC+ ABCo discrimination. In the remaining experiments, training was of the form, A+ B+ C+ AB+ AC+ BC+ ABCo. The discrimination between the single stimuli A+ B+ C+ and ABCo consistently developed more readily than between the pairs of stimuli AB+ AC+ BC+, and ABCo. The results are shown to be more consistent with a configural than with an elemental theory of conditioning.
Conducted 4 experiments with male Sprague-Dawley rats (N = 80) testing the proposition that a compound stimulus, AB, may be conceptualized as composed of the individual A and B elements as well as a separate stimulus unique to their combination. Together with an assumption about limitations on the total associative strength of the compound, this conceptualization can account for the learning of various configural conditioning paradigms. Each experiment examined whether the hypothesized unique stimulus has properties like those of a separable element. Results indicate that, like the separate elements, the unique stimulus can acquire associative strength which is either excitatory or inhibitory, which summates with other associative strengths, which influences the effectiveness of reinforcement and nonreinforcement, and which is attenuated when the unique stimulus becomes irrelevant to reinforcement. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
In 3 experiments, the effect of adding an irrelevant stimulus to a discrimination was examined. In Exp 1, a group of pigeons received autoshaping with an A+
Bo discrimination in which 1 stimulus signaled food, A+, and a simultaneous compound of A with another stimulus, B, signaled the absence of food, ABo. A 2nd group received similiar training, except that a 3rd stimulus, C, was present in both types of trials, AC+
BCo. The A+
Bo discrimination was acquired more readily than the AC+
BCo discrimination. Exps 2 and 3 used a negative-patterning design, A+
Bo+. In both experiments, this problem was mastered more readily than when an irrelevant stimulus was used to create an AC+
BCoC+ discrimination. The results fail to confirm predictions derived from elemental theories of conditioning. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
In 4 experiments, pigeons received autoshaping with various combinations of three stimuli, A, B, and C, before test trials in which responding during all three stimuli, ABC, was compared with that during a three-element control compound, DEF, which had been consistently paired with food. Pairing A, B, and C individually with food resulted in similar rates of responding during ABC and DEF (Experiments 1 and 2). Responding was faster, however, during ABC than during DEF after training in which food was signaled by the pairs of stimuli (AB, AC, and BC; Experiment 1). Responding was also faster during ABC than during DEF after training involving reinforced (
+) and nonreinforced (°) trials of the form ABC
+ A° BC°, followed by A
+ (Experiment 2), or AB
+ B° (Experiments 3 and 4). The results are consistent with those of a configural analysis of summation. (PsycINFO Database Record (c) 2012 APA, all rights reserved)
In each of four experiments, rats drank a solution of saline or of lemon and saline shortly before receiving an injection of lithium chloride, and the generalization of the resulting aversion to sucrose or to lemon and sucrose was measured. There was little generalization from saline alone to sucrose alone, and prior exposure to the two solutions had no effect on their discriminability. An aversion conditioned to lemon-saline, however, did generalize to lemon-sucrose, and the extent of this generalization was substantially reduced by prior exposure to the two compound solutions. This perceptual learning effect was partly, but not entirely, attributable to the latent inhibition of the common element, lemon, produced by exposure to the two compounds: animals pre-exposed to lemon alone discriminated between lemon-saline and lemon-sucrose better than animals pre-exposed to saline and sucrose alone; but exposure to the three elements in isolation was not as effective as exposure to the two compound solutions in enhancing their discriminability. The final experiment established that one critical feature of compound pre-exposure is that it involves experience of saline and sucrose in the presence of the same common element. According to an associative theory of perceptual learning, this would result in the establishment of inhibitory associations between saline and sucrose, thus reducing generalization between the two compound solutions.
A selective review of experiments that can be said to demonstrate the effects of generalization decrement in Pavlovian condition is presented, and it is argued that an adequate theoretical explanation for them is currently not available. This article then develops a theoretical account for the processes of generalization and generalization decrement in Pavlovian conditioning. It assumes that animals represent their environment by a stimulus array in a buffer and that this array in its entirety constitutes the conditioned stimulus. Generalization is then held to occur whenever at least some of the stimuli represented in the array on a test trial are the same as at least some of those represented in the array during training. Specifically, the magnitude of generalization is determined by the proportion of the array occupied by these common stimuli during training compared to the proportion of the array they occupy during testing. By adding to this principle rules concerning excitatory and inhibitory learning, it is proposed, the model can explain all the results that were difficult for its predecessors to account for.
The 1st part of this article evaluates the extent to which 2 elemental theories of conditioning, stimulus sampling theory and the Rescorla-Wagner (1972) theory, are able to account for the influence of similarity on discrimination learning. A number of findings are reviewed that are inconsistent with predictions derived from these theories, either in their present form or in various modified forms. The 2nd part of the article is concerned with developing an alternative, configural account for discrimination learning. In contrast to previous configural theories, the present version is set within the framework of a connectionist network.
This paper describes three theoretical approaches to the representation of configural cues in generalization and discrimination in Pavlovian conditioning: that of the Rescorla-Wagner model, the Pearce model, and the authors' 'replaced elements' model. We summarize the results of a generalization experiment using the rabbit Pavlovian conditioned eyeblink response where animals were trained with cues A, AB, or ABC, and tested with A, AB, and ABC. The pattern of generalization decrement in testing supported the replaced elements model.
We report three Pavlovian eyelid conditioning experiments with humans, designed to experimentally decide between elemental and configural learning theories. We used two different designs originally proposed by Redhead and Pearce (1995). In Experiments 1 and 2, three stimulus elements, A, B, and C, were presented in all possible combinations. All patterns were reinforced except for pattern ABC (A/B/C+, AB/AC/BC+, ABC-). According to elemental learning theories, response proportions on A/B/C+ trials should be smaller than on AB/AC/BC+ trials, whereas configural learning theory makes the opposite prediction. The results confirmed neither prediction. In Experiment 3, the A/B/C+, AB/AC/BC+, and ABC- trials were interspersed by D/E/F-, DE/DF/EF-, DEF+ trials. Again, neither prediction was confirmed. We suggest a modification of configural learning theory as a possible explanation of our results.
An eyetracking version of the classic Shepard, Hovland, and Jenkins (1961) experiment was conducted. Forty years of research has assumed that category learning often involves learning to selectively attend to only those stimulus dimensions useful for classification. We confirmed that participants learned to allocate their attention optimally. We also found that learners tend to fixate all stimulus dimensions early in learning. This result obtained despite evidence that participants were also testing one-dimensional rules during this period. Finally, the restriction of eye movements to only relevant dimensions tended to occur only after errors were largely (or completely) eliminated. We interpret these findings as consistent with multiple-systems theories of learning which maximize information input in order to maximize the number of learning modules involved, and which focus solely on relevant information only after one module has solved the learning problem.
The Psychology of Colour (Wie Farben auf Gefühl und Verstand wirken)
Heller, E., 2004. The Psychology of Colour (Wie Farben auf Gefühl und Verstand
wirken). Gustavo Gili, Barcelona (Original work published 2000).