Extinction of the context and latent inhibition

The hypothesis that latent inhibition could be reduced by extinguishing the experimental context, that is, exposing the rats to the context between exposure to the conditional stimulus (CS) and conditioning, was tested. All experiments used the conditioned emotional response procedure. In Experiment 1, extinction was not effective when the animals were exposed to the clicker 40 times off the baseline of responding for food and when the clicker CS was partially reinforced with shocks during the test phase. In Experiments 2 and 3, latent inhibition could be reduced by extinction if the animals were exposed to the CS 24 or 16 times on-baseline, and if continuous reinforcement was used during the test. In Experiments 4, 5, and 6, we attempted to determine which variable was responsible for the discrepant results. In Experiment 4, extinction was effective with 20 or 40 on-baseline exposures to the CS, using continuous reinforcement during the test. In Experiment 5, extinction was not effective with exposure on- or off-baseline, using 24 exposures and partial reinforcement. Finally, in Experiment 6, extinction reduced latent inhibition using continuous, but not partial, reinforcement with 40 exposures off-baseline. From these results, we concluded that Wagner's model of habituation was not sufficient to account for latent inhibition and that a hybrid model, using both associative and cognitive representational processes, was necessary.     

A search for context-stimulus associations in latent inhibition

Six experiments investigated the effects of pre-exposure to a tone on the subsequent acquisition of conditioned suppression by rats. In Experiments 1-3 the response suppressed was drinking; in Experiments 4-6 it was food-rewarded lever pressing. Repeated exposure to the tone resulted in latent inhibition, i.e., a retardation in the acquisition of suppression. The size of the latent inhibition effect was reduced when a different context was used for conditioning from that used for pre-exposure (Experiment 2). When the context remained the same throughout, a phase of exposure to the context alone, interposed between pre-exposure and conditioning, had no influence on the size of the latent inhibition effect ultimately observed. This last result casts doubt upon Wagner's (1976, 1979) theory of the role of contextual factors in latent inhibition, and alternative accounts are considered.     

Latent inhibition and “psychotic proneness” in normal subjects

Fifty-three normal subjects with no history of psychiatric disorders were tested on an auditory task for the measurement of latent inhibition, i.e. the ability to ignore stimuli previously presented repeatedly without reinforcement and so rendered irrelevant. In acute schizophrenic subjects and in animals given amphetamine this ability is disrupted but can be restored by anti-psychotic drugs. Thus, within the framework of the dimensional analysis of psychosis, it was predicted that the disposition to psychosis in normals may be reflected in the degree of latent inhibition. The sample was subdivided into high and low “psychosis prone” individuals on the basis of: (a) the P scale of the EPQ (Eysenck and Eysenck, 1975); (b) Claridge's STA scale measuring schizotypal personality traits (Claridge and Broks, 1984); and (c) scores on the LSHS, a measure of the tendency to experience hallucinations (Launay and Slade, 1981). The results supported the hypothesis: while a general latent inhibition main effect was evident, high-P scorers showed significantly less latent inhibition, i.e. less retardation of learning to the irrelevant stimulus. A similar trend was also found in the comparison between high and low STA scorers, but not when the degree of predisposition to psychosis was determined by the LSHS. The results are discussed in relation to the dimensional view of psychosis, the amphetamine model of schizophrenia and the processing of irrelevant information as measured by the latent inhibition procedure.     

Syntactic Representations Are Both Abstract and Semantically Constrained: Evidence From Children’s and Adults’ Comprehension and Production/Priming of the English Passive

All accounts of language acquisition agree that, by around age 4, children’s knowledge of grammatical constructions is abstract, rather than tied solely to individual lexical items. The aim of the present research was to investigate, focusing on the passive, whether children’s and adults’ performance is additionally semantically constrained, varying according to the distance between the semantics of the verb and those of the construction. In a forced-choice pointing study (Experiment 1), both 4- to 6-year olds (N = 60) and adults (N = 60) showed support for the prediction of this semantic construction prototype account of an interaction such that the observed disadvantage for passives as compared to actives (i.e., fewer correct points/longer reaction time) was greater for experiencer-theme verbs than for agent-patient and theme-experiencer verbs (e.g., Bob was seen/hit/frightened by Wendy). Similarly, in a production/priming study (Experiment 2), both 4- to 6-year olds (N = 60) and adults (N = 60) produced fewer passives for experiencer-theme verbs than for agent-patient/theme-experiencer verbs. We conclude that these findings are difficult to explain under accounts based on the notion of A(rgument) movement or of a monostratal, semantics-free, level of syntax, and instead necessitate some form of semantic construction prototype account.     

Latent inhibition and conditioning after preexposure to the training context

Experiment 1, using the conditioned suppression technique with rats, showed that the retardation of learning produced by prior exposure to a stimulus (latent inhibition) was more marked in subjects given an initial phase of preexposure to the training context. This effect was confirmed and extended in Experiment 2 in which an appetitive conditioning procedure was used. Experiments 3 and 4, again using conditioned suppression, found no effect of preexposure to the context on the acquisition of suppression when training was given with a novel stimulus, either immediately after preexposure or after a delay; but context preexposure was again found to be effective when exposure to the to-be-conditioned stimulus was given in the delay interval between context preexposure and conditioning. The implications of these findings for accounts of the role of contextual factors in latent inhibition are discussed.     

Effect of a retention interval between pre-exposure and conditioning on latent inhibition in humans using a blink conditioning procedure

Latent inhibition, retarded learning after pre-exposure to the to-be-conditioned stimulus, was examined using a blink conditioned procedure in humans. Experiment 1 showed that the procedure is suited to inducing the latent inhibition effect. In Experiment 2, the introduction of a 3-minute interval between pre-exposure and conditioning phases attenuated latent inhibition. These results contribute to identify the mechanisms involved in pre-exposure and subsequent conditioning of a stimulus, which is particularly important if we bear in mind that latent inhibition has been used repeatedly as an instrument to analyze the course of attentional processes in normal and pathological populations.     

Attenuation of latent inhibition after compound conditioning

Using a conditioned suppression procedure with rats, three experiments examined the effects of compound conditioning on the degree of latent inhibition. Experiment 1 suggested that latent inhibition of the preexposed target was not enhanced but rather attenuated when a second stimulus was presented in compound conditioning. Experiment 2 showed that a similar result was obtained when, in subjects given only compound conditioning, the salience of the target was reduced to the level where it was overshadowed by the second stimulus. Experiment 3 proved that addition of the second stimulus only during preexposure, or during both preexposure and conditioning, did not attenuate the latent inhibition to the target. These results are difficult to explain by any model of Pavlovian conditioning which assumes that both latent inhibition and overshadowing effects are a consequence of acquisition deà cit; other possible accounts are discussed.     

Reinforced stimulus preexposure effects as a function of US intensity: Implications for understanding the Hall-Pearce effect

Three conditioned suppression experiments examined the Hall-Pearce (1979) negative transfer effect in rats. Experiment 1 replicated the effect: CS-US_weak pairings retarded subsequent fear conditioning to the CS as a result of CS-US_strong pairings. The size of this retardation was less than that produced by non-reinforced CS presentations (latent inhibition). When the magnitude of the US_weak was reduced in Experiment 2, the Hall-Pearce effect was greater than latent inhibition. Experiment 3 confirmed the findings of the two previous experiments, and demonstrated that magnitude of the Hall-Pearce negative transfer effect is inversely related to the magnitude of the US_weak. From these findings it is suggested that the Hall-Pearce effect consists of a balance between a positive transfer of associative strength, and negative transfer based on CS- and US-preexposure effects.     

“Tell me more about this…”: An examination of the efficacy of follow-up open questions following an initial account

In information gathering interviews, follow-up questions are asked to clarify and extend initial witness accounts. Across two experiments, we examined the efficacy of open-ended questions following an account about a multi-perpetrator event. In Experiment 1, 50 mock-witnesses used the timeline technique or a free recall format to provide an initial account. Although follow-up questions elicited new information (18–22% of the total output) across conditions, the response accuracy (60%) was significantly lower than that of the initial account (83%). In Experiment 2 (N = 60), half of the participants received pre-questioning instructions to monitor accuracy when responding to follow-up questions. New information was reported (21–22% of the total output) across conditions, but despite using pre-questioning instructions, response accuracy (75%) was again lower than the spontaneously reported information (87.5%). Follow-up open-ended questions prompt additional reporting; however, practitioners should be cautious to corroborate the accuracy of new reported details.     

Role of context in perceptual learning in maze discriminations

Three experiments with rats in a maze examined the effects of pre-exposure to the relevant discriminative stimuli (rubber and sandpaper-covered maze arms) or the extra-maze context (the maze was surrounded either by black curtains or by variety of extra-maze landmarks) on the learning of a discrimination between rubber and sandpaper arms. In Experiment 1, pre-exposure to the extra-maze context facilitated subsequent discrimination learning. Experiments 2 and 3 showed that pre-exposure to rubber and sandpaper arms facilitated subsequent discrimination learning only when these cues were presented in the same context during pre-exposure and discriminative training. Taken together, the results are consistent with the hypothesis that a major cause of perceptual learning is the latent inhibition of stimuli or features common to the two discriminative stimuli, and that such latent inhibition may be disrupted by a radical change of context.     

Gesture Helps,Only If You Need It: Inhibiting Gesture Reduces Tip-of-the-Tongue Resolution for Those With Weak Short-Term Memory

People frequently gesture when a word is on the tip of their tongue (TOT), yet research is mixed as to whether and why gesture aids lexical retrieval. We tested three accounts: the lexical retrieval hypothesis, which predicts that semantically related gestures facilitate successful lexical retrieval; the cognitive load account, which predicts that matching gestures facilitate lexical retrieval only when retrieval is hard, as in the case of a TOT; and the motor movement account, which predicts that any motor movements should support lexical retrieval. In Experiment 1 (a between-subjects study; N = 90), gesture inhibition, but not neck inhibition, affected TOT resolution but not overall lexical retrieval; participants in the gesture-inhibited condition resolved fewer TOTs than participants who were allowed to gesture. When participants could gesture, they produced more representational gestures during resolved than unresolved TOTs, a pattern not observed for meaningless motor movements (e.g., beats). However, the effect of gesture inhibition on TOT resolution was not uniform; some participants resolved many TOTs, while others struggled. In Experiment 2 (a within-subjects study; N = 34), the effect of gesture inhibition was traced to individual differences in verbal, not spatial short-term memory (STM) span; those with weaker verbal STM resolved fewer TOTs when unable to gesture. This relationship between verbal STM and TOT resolution was not observed when participants were allowed to gesture. Taken together, these results fit the cognitive load account; when lexical retrieval is hard, gesture effectively reduces the cognitive load of TOT resolution for those who find the task especially taxing.     

Strategic control of sentence context effects in a naming task

This paper reports an experiment that demonstrates strategic influences on sentence context effects in a naming task. The size of the sentence context effect is shown to be influenced by the validity of the contextual information. A similar result is obtained simply by changing the proportion of validly completed sentences in the practice session without altering the composition of the experimental trials themselves. The manipulation of context validity was found to have its effect largely on the facilitatory component of the context effect. This dissociation of facilitation and inhibition is shown to be contrary to the predictions of attentional accounts of priming but in line with an explanation of contexts effects based on a mechanism that has evolved primarily to resolve lexical and perceptual ambiguity (Norris, 1986). In a further experiment it is shown that the facilitatory effects of sentence context observed in Experiment 1 are not dependent on the particular baseline condition employed.     

Centre–surround inhibition is a general aspect of famous-person recognition: Evidence from negative semantic priming from clearly visible primes

A centre–surround attentional mechanism was proposed by Carr and Dagenbach (Journal of Experimental Psychology: Learning, Memory, and Cognition 16: 341–350, 1990) to account for their observations of negative semantic priming from hard-to-perceive primes. Their mechanism cannot account for the observation of negative semantic priming when primes are clearly visible. Three experiments (Ns = 30, 46, and 30) used a familiarity decision with names of famous people, preceded by a prime name with the same occupation as the target or with a different occupation. Negative semantic priming was observed at a 150- or 200-ms SOA, with positive priming at shorter (50-ms) and longer (1,000-ms) SOAs. In Experiment 3, we verified that the primes were easily recognisable in the priming task at an SOA that yielded negative semantic priming, which cannot be predicted by the original centre–surround mechanism. A modified version is proposed that explains transiently negative semantic priming by proposing that centre–surround inhibition is a normal, automatically invoked aspect of the semantic processing of visually presented famous names.     

Involuntary transfer of a top-down attentional set into the focus of attention: Evidence from a contingent attentional capture paradigm

In the present study, we investigated whether involuntarily directing attention to a target-colored distractor causes the corresponding attentional set to enter a limited-capacity focus of attention, thereby facilitating the identification of a subsequent target whose color matches the same attentional set. As predicted, in Experiment 1, contingent attentional capture effects from a target-colored distractor were only one half to one third as large when subsequent target identification relied on the same (vs. a different) attentional set. In Experiment 2, this effect was eliminated when all of the target colors matched the same attentional set, arguing against bottomup perceptual priming of the distractor’s color as an alternative account of our findings. In Experiment 3, this effect was reversed when a target-colored distractor appeared after the target, ruling out a feature-based interference account of our findings. We conclude that capacity limitations in working memory strongly influence contingent attentional capture when multiple attentional sets guide selection.     

The influence of a distractor during compound preexposure on latent inhibition

Nonreinforced exposure to a nontarget stimulus that was followed by nonreinforced exposure to a target/nontarget simultaneous compound stimulus resulted in enhanced latent inhibition of the target. Conditioning was slower after this treatment than after nonreinforced exposure to the target stimulus alone (Experiment 1). However, a salient auditory stimulus presented immediately after the compound in the second phase reduced levels of latent inhibition, relative to the enhanced latent inhibition produced when no such extracompound stimulus was presented (Experiments 2 and 3). This effect was not noted if the salient auditory cue was presented 10 sec after the termination of the compound stimulus (Experiment 4). In Experiment 5, there was no disruption of simple latent inhibition produced by a salient stimulus. These results are consistent with enhanced latent inhibition's being produced by the formation of within-compound associations, which are disrupted by the salient extracompound stimuli.     

Exogenous attention differentially modulates the processing of categorical and coordinate spatial relations

Carrasco and her colleagues have suggested that exogenous attention reduces the size of receptive fields at an attended location (Gobell & Carrasco, 2005; Yeshurun & Carrasco, 1998, 2000). Based on the hypothesis that categorical and coordinate spatial relations are more efficiently processed by smaller and larger receptive fields, respectively, we predicted that exogenous attention would be more beneficial to the processing of categorical spatial relations than coordinate spatial relations while it would disrupt the processing of coordinate spatial relations. To test these hypotheses, participants were tested using a variant of Posner's (1980) attentional cueing paradigm. Exogenous attention produced larger facilitative effects on categorical spatial processing than on coordinate spatial processing at a short cue-target stimulus onset asynchrony (100 ms, Experiment 1, N = 28), and this result was replicated regardless of cue size in Experiment 2 (N = 24). When the coordinate judgment was sufficiently difficult, exogenous attention disrupted the processing of coordinate spatial relations (Experiment 3, N = 28). These findings indicate that exogenous attention can differentially modulate the processing of categorical and coordinate spatial relations.     

Top-up search and the attentional blink: A two-stage account of the preview effect in search

An inefficient visual search task can be facilitated if half the distractor items are presented as a preview prior to the presentation of the remaining distractor items and target. This benefit in search is termed the preview effect. Recent research has found that a preview effect can still occur if the previewed items disappear before reappearing again just before the search items (the “top-up” procedure). In this paper we investigate the attentional demands of processing during the preview and the top-up periods. Experiment 1 found that if attention is withdrawn from the top-up stage then no preview effect occurs. Likewise if attention is withdrawn from the initial preview period then the preview effect is reduced (Experiment 2). The data suggest that the preview effect is dependent on attention being paid both to the initial display and also to the re-presentation of the old display before the search display appears. The data counter accounts of preview search in terms of automatic attention capture by new items or by inhibition of return. We discuss alternative accounts of the results, and in particular suggest an amalgamation of a temporal grouping and a visual marking account of preview search.     

Perceptual Learning in the Rat: Stimulus Differentiation or Latent Inhibition of Common Elements?

Preexposure to an unreinforced stimulus facilitates learning (perceptual learning) under some conditions, but it can have the opposite effect (latent inhibition) under other conditions. Researchers have suggested that perceptual learning depends on a change of context, whereas latent inhibition is usually context specific. The associative theory explains both phenomena within a single framework. The authors report 4 experiments that show that perceptual learning does not depend on a context change. The experiments suggest that latent inhibition, unlike perceptual learning, depends on passive exposure. Thus the results do not support the associative theory. They are more consistent with Gibson's stimulus-differentiation theory.     

Effects of Retention Interval on Latent Inhibition and Perceptual Learning

Repeated, non-reinforced preexposure to a context slowed development of conditioned freezing to that context when it was subsequently paired with footshock (latent inhibition) and enhanced discriminability of that context from a similar context (perceptual learning) whether assessed by a generalization test or by explicit discrimination training. Latent inhibition was eliminated by a delay between conditioning sessions and test (Experiments 1a and 1b) and reduced by a delay between preexposure and conditioning (Experiment 2). However, perceptual learning was unaffected by either of these intervals (Experimnets 1b and 2). These results are discussed in terms their impact on theories that have latent inhibition as a possible mechanism of perceptual learning, and on theories of latent inhibition that consider the retardation of conditioned responding to be the result of an acquisition failure.     

Latent inhibition, context specificity, and context familiarity

In two appetitive licking experiments, thirsty rats were pre-exposed to two stimuli prior to conditioning sessions in which one or both of these stimuli were paired with water. Consistent with other results, latent inhibition was disrupted when conditioning took place in a context different from that in which stimulus pre-exposure had occurred. But in animals given prior exposure to the context of stimulus pre-exposure before the start of stimulus pre-exposure, substantial and equivalent latent inhibition was evident whether or not there was a change of context between stimulus pre-exposure and conditioning. These results are discussed in terms of current theories of latent inhibition.