22,818 research outputs found

    Posttraining Shifts in the Overshadowing Stimulus–Unconditioned Stimulus Interval Alleviates the Overshadowing Deficit

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    Two conditioned lick suppression experiments explored the effects on overshadowing of a posttraining change in the temporal relationship between the overshadowing conditioned stimulus (CS) and the unconditioned stimulus (US). Rats received either trace (Experiment 1) or delay (Experiment 2) overshadowing training. Then pairings of the overshadowing CS and US were given with either a trace or delay temporal relationship. Overshadowing was alleviated by shifting the overshadowing CS–US temporal relationship so that it no longer matched the overshadowed CS–US temporal relationship. These outcomes are explicable in terms of an integration of the comparator hypothesis, which states that cue competition effects (e.g., overshadowing) will be maximal when the information potentially conveyed by competing CSs is equivalent, and the temporal coding hypothesis, which states that CS–US intervals are part of the information encoded during conditioning

    When distraction helps: Evidence that concurrent articulation and irrelevant speech can facilitate insight problem solving

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    We report an experiment investigating the “special-process” theory of insight problem solving, which claims that insight arises from non-conscious, non-reportable processes that enable problem re-structuring. We predicted that reducing opportunities for speech-based processing during insight problem solving should permit special processes to function more effectively and gain conscious awareness, thereby facilitating insight. We distracted speech-based processing by using either articulatory suppression or irrelevant speech, with findings for these conditions supporting the predicted insight facilitation effect relative to silent working or thinking aloud. The latter condition was included to investigate the currently contested effect of “verbal overshadowing” on insight, whereby thinking aloud is claimed to hinder the operation of special, non-reportable processes. Whilst verbal overshadowing was not evident in final solution rates, there was nevertheless support for verbal overshadowing up to and beyond the mid-point of the available problem solving time. Overall our data support a special-process theory of insight, whilst also pointing to the role of moderator variables (e.g., available time for solution) in determining the presence or absence of effects predicted by the special-process account

    Intraperitoneal sertraline and fluvoxamine increase contextual fear conditioning but are without effect on overshadowing between cues

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    Treatment with selective serotonin reuptake inhibitors (SSRIs) can reduce contextual conditioning. Since contexts present a variety of potentially competing cues, impaired overshadowing may provide an account of such effects. The present study therefore compared the effects of two SSRIs on overshadowing and contextual conditioning, testing suppression of an ongoing behavioral response (licking) by cues previously paired with foot shock. Conditioning to a 5s light stimulus was reduced when this was presented in compound with a 5s noise, thus overshadowing was demonstrated. In two experiments, this overshadowing was unaffected by treatment with either sertraline or fluvoxamine. However, unconditioned suppression to the noise (tested in the control group previously conditioned to the light alone) was reduced after sertraline (10mg/kg, i.p.). The successful demonstration of overshadowing required the use of a second conditioning session or an additional conditioning trial within the same conditioning session. Neither weak nor strong overshadowing (of the light by the tone) was affected by any drug treatment. Moreover, counter to prediction, conditioning to contextual cues was increased rather than impaired by treatment with sertraline (10mg/kg, i.p.) and fluvoxamine (30mg/kg, i.p.)

    Verbal Overshadowing and the Effects of Earwitness Testimony on the Likelihood of Correct Identification of Target Voices

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    Verbal overshadowing is the process by which verbalizing memory interferes with the original memory (Schooler & Engstler-Schooler, 1990). While verbal overshadowing is robust with eyewitness events, it is not a definite occurrence. However, can verbal overshadowing affect memories of auditory information? Previous research on earwitness testimony has shown a verbal overshadowing effect in which the ability to accurately identify a witness\u27s voice is impaired after verbally describing the voice participants heard (Perfect, Hunt, & Harris, 2002). I examined how voice lineup identification may be influenced by verbally describing a presented voice, a nonpresented voice, or an unrelated event. Results did not suggest a verbal overshadowing effect when the presented voice was described

    Temporal Encoding as a Determinant of Overshadowing

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    Three conditioned lick suppression experiments explored the effects on overshadowing of the temporal relationships of two conditioned stimuli (CSs) with an unconditioned stimulus (US). Assuming overshadowing is maximal when the potential information conveyed by two competing CSs is equivalent, the temporal coding hypothesis predicts that greater overshadowing will be observed when the CSs share the same temporal relationship with the US. Rats were exposed to an overshadowing CS that had either a forward, simultaneous, or backward relationship to the US. The relationship of the overshadowed CSs to the US was either forward (Experiment 1), simultaneous (Experiment 2), or backward (Experiment 3). The greatest amount of overshadowing was observed when both CSs had the same temporal relationship to the US. The data are discussed within the framework of the temporal coding hypothesis and of alternative models of Pavlovian conditioning based on the informational hypothesis

    Overshadowing depends on cue and reinforcement sensitivity but not schizotypy

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    There is evidence for impaired selective learning mechanisms in individuals high in schizotypy. Overshadowing provides a direct test of selective learning based on cue salience and has previously been reported to be impaired in relation to schizotypy scores. The present study tested for overshadowing using food allergy and Lego construction task variants. Both variants used the same number of conditioned stimulus (CS) cues and the same number of learning trials. CS cues were trained in compound pairs or in isolation and overshadowing was subsequently tested on trials followed by negative versus positive outcomes. Participants also completed the O-LIFE to measure schizotypy and BIS-BAS scales to measure reinforcement sensitivity. Learning was demonstrated for both cue variants; however overshadowing emerged only in the Lego variant and only on the trials followed by the negative outcome. Contrary to expectations, there was no evidence for any relationship between overshadowing and O-LIFE scores. However, there was evidence of a positive relationship between overshadowing and BAS-Drive as well as a negative relationship with BIS-Anxiety, for the trials followed by the positive outcome in the food allergy variant. These results suggest that the development of overshadowing depends on cue and reinforcement sensitivity, but not necessarily on schizotypy

    ROC analysis of the verbal overshadowing effect: testing the effect of verbalisation on memory sensitivity

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    This study investigated the role of memory sensitivity versus recognition criterion in the verbal overshadowing effect (VOE). Lineup recognition data was analysed using ROC analysis to separate the effects of verbalisation on memory sensitivity from criterion placement. Participants watched a short crime video, described the perpetrator's facial features then attempted a lineup identification. Description instructions were varied between participants. There was a standard (free report), forced (report everything), and warning (report accurate information) condition. Control participants did not describe the perpetrator. Memory sensitivity was greater in the control compared to the standard condition. Memory sensitivity was also greater in the warning compared to forced and standard conditions. Memory sensitivity did not differ across the forced and standard description conditions, although a more conservative lineup decision standard was employed in the forced condition. These results, along with qualitative analyses of descriptions, support both retrieval-based and criterion-based explanations of the VOE

    Renewal of Comparator Stimuli

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    Prior research has found a) recovery from overshadowing as a result of posttraining extinction of comparator stimuli (i.e., the overshadowing stimulus), and b) context modulation of conditioned responding to Pavlovian stimuli (i.e., renewal). The present research brought together these two findings by investigating whether comparator stimuli are subject to contextual control. In a Pavlovian conditioned suppression situation, rats were exposed to an overshadowing procedure (i.e., AX1) in one context and then received extinction of the overshadowing cue (i.e., A2) in the same or a different context. If AX1 training and subsequent extinction of A occurred in the same context, animals exhibited recovery of responding to the target cue (i.e., X) regardless of the test context. However, if AX1 training and extinction of A occurred in different contexts, behavior depended on the test context. If X was tested in the overshadowing context, overshadowing was observed. But if X was tested in the context where A had been extinguished or in a third (neutral) context, overshadowing was not observed. Thus, context modulates comparator effects in a manner somewhat similar to how it modulates simple Pavlovian responding. The notable exception was that robust responding to both A and X was observed in the neutral context, which is problematic for most contemporary theories of learning

    Dopamine in nucleus accumbens: salience modulation in latent inhibition and overshadowing

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    Latent inhibition (LI) is demonstrated when non-reinforced pre-exposure to a to-be-conditioned stimulus retards later learning. Learning is similarly retarded in overshadowing, in this case using the relative intensity of competing cues to manipulate associability. Electrolytic/excitotoxic lesions to shell accumbens (NAc) and systemic amphetamine both reliably abolish LI. Here a conditioned emotional response procedure was used to demonstrate LI and overshadowing and to examine the role of dopamine (DA) within NAc. Experiment 1 showed that LI but not overshadowing was abolished by systemic amphetamine (1.0 mg/kg i.p.). In Experiment 2, 6-hydroxydopamine (6-OHDA) was used to lesion DA terminals within NAc: both shell- and core- (plus shell-)lesioned rats showed normal LI and overshadowing. Experiment 3 compared the effects of amphetamine microinjected at shell and core coordinates prior to conditioning: LI, but not overshadowing, was abolished by 10.0 but not 5.0 µg/side amphetamine injected in core but not shell NAc. These results suggest that the abolition of LI produced by NAc shell lesions is not readily reproduced by regionally restricted DA depletion within NAc; core rather than shell NAc mediates amphetamine-induced abolition of LI; overshadowing is modulated by different neural substrates

    Cue Competition as a Retrieval Deficit

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    Four experiments using rats as subjects investigated the claim of Williams (1996) that cue competition results from an associative acquisition deficit, rather than a performance deficit. In Experiment 1, extinction of an overshadowing stimulus following overshadowing treatment increased responding to the overshadowed stimulus, thereby replicating prior observations with new parameters. In Experiment 2, an overshadowed stimulus failed to support second-order conditioning unless the overshadowing stimulus received prior extinction treatment. Experiment 3 replicated the recovery from overshadowing effect seen in Experiment 1 using a sensory preconditioning procedure. Most important, in Experiment 4 an overshadowed stimulus failed to block conditioned responding to a novel CS, but blocking by the overshadowed cue was observed following posttraining extinction of the overshadowing stimulus. These results, as well as those of Williams, are discussed in terms of traditional and more recent acquisition-focused models as well as an extension of the comparator hypothesis ( Denniston, Savastano, & Miller, 2001)
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