David N. George

Attention and associative learning in humans: An integrative review.

This article presents a comprehensive survey of research concerning interactions between associative learning and attention in humans. Four main findings are described. First, attention is biased toward stimuli that predict their consequences reliably (learned predictiveness). This finding is consistent with the approach taken by Mackintosh (1975) in his attentional model of associative learning in nonhuman animals. Second, the strength of this attentional bias is modulated by the value of the outcome (learned value). That is, predictors of high-value outcomes receive especially high levels of attention. Third, the related but opposing idea that uncertainty may result in increased attention to stimuli (Pearce & Hall, 1980), receives less support. This suggests that hybrid models of associative learning, incorporating the mechanisms of both the Mackintosh and Pearce-Hall theories, may not be required to explain data from human participants. Rather, a simpler model, in which attention to stimuli is determined by how strongly they are associated with significant outcomes, goes a long way to account for the data on human attentional learning. The last main finding, and an exciting area for future research and theorizing, is that learned predictiveness and learned value modulate both deliberate attentional focus, and more automatic attentional capture. The automatic influence of learning on attention does not appear to fit the traditional view of attention as being either goal-directed or stimulus-driven. Rather, it suggests a new kind of “derived” attention.

A configural theory of attention and associative learning

A formal account of the relationship between attention and associative learning is presented within the framework of a configural theory of discrimination learning. The account is based on a connectionist network in which the entire pattern of stimulation presented on a trial activates a configural unit that then enters into an association with the trial outcome. Attention is assumed to have two roles within this network. First, the salience of the stimuli at the input to the network can be increased if they are relevant to the occurrence of reinforcement and decreased if they are irrelevant. Second, the associability of configural units can increase on trials when the outcome is surprising and decrease when the outcome is not surprising.

Summation: further assessment of a configural theory

Rats received Pavlovian conditioning in which food was signalled by a visual stimulus, A+, an auditory stimulus, B+, and a compound composed of different visual and auditory stimuli, CD+. Test trials were then given with the compound AB. Experiments 1 and 2A revealed stronger responding during AB than during CD. In Experiment 2B, there was no evidence of a summation of responding during AB when A+ B+ training was conducted in the absence of CD+ trials. A further failure to observe abnormally strong responding during ABwas found in Experiment 3 for which the training trials with A+ B+ CD+ were accompanied by trials in which C and D were separately paired with food. The results are explained in terms of a configural theory of conditioning, which assumes that responding during a compound is determined by generalization from its components, as well as from other compounds to which it is similar.

Pavlovian-to-Instrumental Transfer: Paradoxical Effects of the Pavlovian Relationship Explained

Four experiments with rats examined the origin of outcome-selective Pavlovian-to-instrumental transfer (PIT). Experiment 1 used a standard procedure, where outcomes were embedded within extended conditioned stimuli (CSs), to demonstrate the basic effect: Pavlovian stimuli augmented instrumental lever presses that had been paired with the same outcomes. Experiments 2 and 3 showed that after instrumental conditioning, whereas a conditioned stimulus (CS) trained using a backward conditioning procedure produced outcome-selective PIT, forward conditioning with a CS did not. These results are consistent with the idea that backward conditioning results in the outcome provoking its associated instrumental response during the CS and thereby allows a stimulus-response association to be acquired that directly generates outcome-selective PIT at test. Experiment 4 provided direct support for the assumptions that underlie this stimulus-response analysis. These results, and other paradoxical effects of the Pavlovian relationship, are incongruent with accounts of outcome-selective PIT that rely on a stimulus-outcome-response chain.

Impaired conditional task performance in a high schizotypy population: Relation to cognitive deficits

Cognitive impairments in schizophrenia have been characterized as reflecting a core deficit in the maintenance or use of task-setting cues to mediate appropriate ongoing behaviour. This analysis suggests that cognitive deficits in schizophrenia will be particularly evident when different task-setting cues dictate when different responses are required by the same stimuli. One simple task in which task-setting cues are required is a biconditional discrimination. Here we examined the performance of participants with high and low schizotypy scores (Mason, Claridge, & Jackson, 1995) on a biconditional discrimination and an otherwise equivalent, control discrimination that did not require the use of task-setting cues. Participants scoring highly on the Introvertive Anhedonia subscale (which has been allied to the negative and cognitive symptoms of schizophrenia) performed poorly on the biconditional, but not on the control, discrimination. No other subscales demonstrated a significant influence on either biconditional or control performance.

Contextual modulation of attention in human category learning.

In a category-learning experiment, we assessed whether participants were able to selectively attend to different components of a compound stimulus in two distinct contexts. The participants were presented with stimulus compounds for which they had to learn categorical labels. Each compound comprised one feature from each of two dimensions, and on different trials the compound was presented in two contexts, X and Y. In Context X, Dimension A was relevant to the solution of the categorization task and Dimension B was irrelevant, whereas in Context Y, Dimension A was irrelevant and Dimension B was relevant. The results of transfer tests to novel stimuli suggested that people learned to attend selectively to Dimension A in Context X and Dimension B in Context Y. These findings contribute to the growing body of evidence that people can learn to selectively attend to particular dimensions of stimuli dependent on the context in which the stimuli are presented. Furthermore, the findings demonstrate that context-dependent changes in attention transfer to other categorization tasks involving novel stimuli.

Extreme elemental processing in a high schizotypy population: Relation to cognitive deficits

The cognitive deficits observed in schizophrenia have been characterized as a failure to utilize task-setting information to guide behaviour, especially in situations in which there is response conflict. Recently, we have provided support for this account; high schizotypy individuals demonstrated inferior biconditional discrimination performance compared to low scorers, but were not impaired on a simple discrimination that did not require the use of task-setting cues. These results may, however, also be explained by the way in which individuals with high schizotypy process stimulus compounds. Here, we examine the initial approaches to solving biconditional and control discrimination tasks of participants with high and low schizotypy scores. In particular, we focus on performance during the first block of training trials to capture processing style before the acquisition of the discrimination tasks. Participants scoring highly on the introvertive anhedonia subscale (which has been allied to the negative and cognitive symptoms of schizophrenia) demonstrated better biconditional performance during the first block of training trials than did low-schizotypy individuals, consistent with a highly elemental approach to stimulus processing. Subsequent recognition tests confirmed this analysis demonstrating that the pattern of performance observed in participants with high schizotypy was associated with a failure to discriminate conjunctions of items that had been seen before from those that had not. These results suggest that the negative/cognitive symptoms of schizophrenia may reflect an extreme bias towards elemental, as opposed to configural, processing of stimulus conjunctions.

Placebo Analgesia from a Rubber Hand

Placebo analgesia, reductions in pain after administration of an inert treatment, is a well documented phenomenon. We report, to our knowledge, the first demonstration that placebo analgesia can be experienced when a sham analgesic is applied onto a rubber hand. The effect was obtained by exploiting the rubber hand illusion, in which ownership is felt over a rubber arm that is unattached to the body. Under conditions of synchronous as well as asynchronous visuotactile stimulation, a thermal pain stimulus was delivered on the real arm of 20 participants and seemingly also on the rubber arm, before and after applying a sham analgesic and a control cream only to the rubber arm. During synchronous visuotactile stimulation, pain was experienced on the rubber arm, and the application of the sham analgesic to the rubber arm significantly decreased the severity of reported pain. This shows that experience of the body can modulate expectations and the induction of placebo analgesia.nnnPERSPECTIVEnThis article presents an experiment suggesting that a placebo treatment applied to a rubber hand during the rubber hand illusion can produce placebo analgesia. This finding indicates that embodiment may influence the placebo effect, a previously unexamined factor in the treatment process with potential applications to treatment administration.

Book Review: Learning: A Very Short IntroductionLearning: a very short introduction, by HaselgroveMark, Oxford: Oxford University Press, 2016, Price: £7.99, ISBN: 978-0199688364

A review of Haselgrove, Mark (2016) Learning: A short introduction. Oxford University Press.

Book review: Learning : a short introduction

A review of Haselgrove, Mark (2016) Learning: A short introduction. Oxford University Press.