R. E. Lubow

Conditioned Attention Theory1

Publisher Summary This chapter deals with a theory to account for the latent inhibition (LI) phenomenon in particular, and other stimulus pre-exposure phenomena with special reference to such paradigms as habituation, learned helplessness, sensory preconditioning, blocking, and the feature positive effect. The theory is based on the application of conditioning principles during the stimulus pre-exposure phase of a transfer experiment conditioned attention theory. LI is a decrement in learning performance that results from repeated non-reinforced pre-exposure of the to-be-conditioned stimulus. Empirical support for these predictions is drawn from a series of experiments specifically designed to evaluate the theory and from experiments designed outside the theorys framework.

Latent inhibition in low and high psychotic-prone normal subjects

Abstract Two experiments were performed with adult human subjects which demonstrated latent inhibition, a retardation of learning following preexposure to a subsequently relevant stimulus. The first study, using an auditory procedure, replicated Baruch. Hemsley and Grays (1988a, Personality and Individual Differences, 9; finding that high “psychotic-prone” normals, as assessed by Eysencks Psychoticism Scale and Claridge and Broks STA Scale, exhibit an attenuated latent inhibition effect as compared to low “psychotic-prones”. The second study, using a newly developed visual procedure, obtained similar results. The attenuation of latent inhibition in high “psychotic-prone” normals was discussed in relation to attentional dysfunction in schizophrenia and the animal dopamine model of schizophrenia.

Are high-schizotypal normal participants distractible or limited in attentional resources? A study of latent inhibition as a function of masking task load and schizotypy level

Two experiments with normal participants examined the effects of masking and masking task load on latent inhibition (LI, poorer learning for a previously exposed irrelevant stimulus than for a novel stimulus) as a function of level of schizotypality. In Experiment 1, a masking task was needed to produce LI. In Experiment 2, with low load, LI was present in low- but not high-schizotypal participants. In high load, LI was abolished in low-schizotypal participants, but only approached significance in high-schizotypal participants. The data support a distraction- rather than a resource-limitation model of attentional dysfunction in high-schizotypal normal participants. In addition, the data indicate that obtaining LI requires that some attention be initially allocated to the preexposed stimulus and then reduced. Implications of the model for understanding attentional dysfunction in schizophrenia are discussed.

An empirical analysis of the super-latent inhibition effect

In three conditioned taste aversion experiments, we examined the roles of several variables in producing super-latent inhibition (LI). This effect, greater LI after a long interval than after a short interval between the conditioning and the test stages (De la Casa & Lubow, 2000), was shown to increase with the number of stimulus preexposures (0, 2, or 4; Experiment 1) and with the length of the delay interval (1, 7, 14, or 21 days; Experiment 2). Furthermore, super-LI was obtained when the delay interval was introduced between the conditioning and the test stages (Experiments 1 and 2), but not when it was introduced between the preexposure and the conditioning stages (Experiment 3). The results are discussed in relation to interference explanations of LI.

Context control of negative transfer induced by preexposure to irrelevant stimuli: Latent inhibition in humans ☆

Abstract New associations to formerly irrelevant stimuli are made more slowly than to the same stimuli when they are novel. This negative transfer phenomenon, termed latent inhibition (LI), has been extensively investigated in the animal literature. The present set of studies examines LI in humans and, in particular, the effects of several types of context manipulations on LI. Four experiments were conducted. LI was produced when the context in which stimulus preexposure occurred was the same as the test context (Experiments 1, 3, and 4). LI was attenuated when the stimulus preexposure and test contexts were different (Experiment 1). LI attenuation also occurred as a function of change of context from preexposure to test when additional context preexposure preceded stimulus preexposure in that context (Experiment 2). An explicit context extinction procedure failed to reduce the amount of LI (Experiment 3). Finally, it was shown that stimulus and context preexposures must occur conjointly in order for LI to develop (Experiment 4). The effects of the different context manipulations on LI are similar to those obtained in animals and congruent with the notion that preexposure context serves as an occasion setter for the activation of a stimulus-no consequence association.

Amphetamine-Produced Attenuation of Latent Inhibition Is Modulated by Stimulus Preexposure Duration: Implications for Schizophrenia

The relationship between amphetamine-produced dopamine overreactivity and attention to irrelevant stimuli is reflected in an attenuated latent inhibition (LI) effect. This occurs in both animal and human subjects. The present study examines the manner in which this effect in rats is modulated by the duration of stimulus preexposure. A factorial design was used with three levels of stimulus preexposure duration and either amphetamine or saline administration. In addition, there were corresponding groups that did not receive stimulus preexposure. It was found that although amphetamine did indeed abolish LI at short exposure intervals (30 sec), the LI effect was normal for long stimulus preexposure durations (150 sec). The data were discussed in terms of the affects of amphetamine on the processing of irrelevant stimuli and the relationship of such a dysfunctional attentional process to schizophrenia.

Super-latent inhibition with delayed conditioned taste aversion testing

In three conditioned taste aversion experiments with rats, latent inhibition (LI) was examined as a function of the time interval (1 or 21 days) between the conditioning and the test phases. In Experiments 1 and 2, the effects of US intensity on LI were examined. LI increased in the 21-day condition, as compared with the 1-day condition, with medium and high US intensity, but not with weak US intensity. Groups not preexposed to the CS flavor had similar aversions when testing was conducted 1 day after conditioning, as compared with 21 days. In Experiment 3A, delay-induced super-LI was obtained when the delay was spent in the home cage and the experimental stages took place in a different context (as in Experiments 1 and 2). In Experiment 3B, when all the stages, including the delay period, were conducted in the home cage, there was no super-LI effect. The modulation of delay-induced super-LI as a function of US intensity and context extinction is discussed in relation to association deficit and retrieval interference theories of LI.

Latent inhibition with a response time measure from a within-subject design: Effects of number of preexposures, masking task, context change, and delay.

Latent inhibition (LI), poorer performance on a learning task to a previously irrelevant stimulus than to a novel stimulus, was produced in 4 experiments, using a within-subject design and a response time (RT) measure. LI was reduced by decreasing the number of stimulus preexposures, omitting the masking task, changing the context from the preexposure to the test phase, and introducing a delay between the 2 phases. Together, these effects indicate that the within-subject RT-based LI reflects the same processes as those that govern between-subject LI with correct response as the dependent measure. The new procedure provides an advantageous method for assessing attentional dysfunction related to the processing of irrelevant stimuli, particularly in pathological groups, such as patients with schizophrenia.

Superlatent inhibition and spontaneous recovery: Differential effects of pre- and postconditioning CS-alone presentations after long delays in different contexts

In two pairs of three-stage conditioned taste aversion experiments, we examined the effects of delay interval (1 or 21 days) between the second and third stages, and of context in which the animals spent the delay (same as or different from the context of the other stages) on latent inhibition (LI) and spontaneous recovery following extinction. In the LI experiments (Experiments 1A and 1B), the first stage comprised nonreinforced presentations to saccharin or to water. In the second stage, rats were conditioned by saccharin paired with LiCl. In the extinction experiments (Experiments 2A and 2B), the order of the stages was reversed. For all experiments, Stage 3, the test stage, consisted of three presentations of saccharin alone. There was a super-LI effect in the saccharin-preexposed group that spent the 21- day delay in the different context (Experiment 1A). When the delay was spent in the same context, there was no difference in the amount of LI between the short- and long-delay groups (Experiment 1B). Conversely, there was a spontaneous recovery effect in the long-delay/same-context group (Experiment 2B), but not in the long-delay/different-context group (Experiment 2A). The pattern of results, incompatible with current explanations of delay-induced changes in memory performance, was interpreted in terms of an interaction between the delay conditions (same or different delay context), which modulate the extinction of previously acquired context-CS-nothing associations (during CS-alone presentations), and primacy effects.

Latent inhibition: The effects of ITI and CS intensity during preexposure☆

Abstract Two experiments are reported which test the effects of intertrial interval (ITI) and stimulus intensity during nonreinforced preexposure in the latent inhibition paradigm. In Experiment 1, using mice in an escape-avoidance task, latent inhibition was a direct function of the duration of stimulus intertrial interval during preexposure. In Experiment 2, using rats in a CER task, latent inhibition was a direct function of stimulus intensity during preexposure. These findings are discussed in terms of equivalent effects which have been reported in the habituation paradigm.