Memory in sub-clinical obsessive-compulsive checkers

In a series of experiments we extended the research on possible memory deficits in subclinical obsessive-compulsive Ss who reported excessive checking. Using a variety of memory tests we compared 20 subclinical checkers to 20 Ss without obsessive-compulsive symptomatology. Contrary to hypothesis, checkers remembered self-generated words better than read words just as much as did normals, but they were more likely than normals to report thinking they had studied words that, in fact, had not been on the study list. Further, they more often confused whether they read or generated the words at study. Checkers did not appear to perseverate on already-recalled words on repeated free recall tests any more than did normals. However, checkers remembered fewer actions overall and more often misremembered whether they had performed, observed, or written these actions. Such memory deficits may contribute to the development of excessive checking.     

Realism of confidence in obsessive-compulsive checkers

The study examined whether obsessive-compulsive (OC) checkers have reduced confidence in their knowledge. OC checkers were compared with panic disorder (PD) patients and nonpatient controls using a calibration-of-knowledge procedure. Participants completed a general knowledge questionnaire, rated their confidence in each answer, and estimated the total number of correct answers. These responses were converted to 2 measures of confidence relative to performance--over/underconfidence and over/underestimation. OC checkers had lower scores than nonpatients did on both measures, whereas the PD patients did not differ from either group. For the OC checkers, relative confidence was inversely related to the severity of obsessions. The authors speculate that confidence may depend on a confirmation bias in testing hypotheses and that the reduced confidence in OC checkers may reflect a disconfirmation bias in this population.     

Prevalence of DSM-III-R disorders among nonclinical compulsive checkers and noncheckers in a college student sample.

The prevalence of lifetime DSM-III-R disorders was assessed in a sample of 100 college students who were classified as compulsive checkers (n = 50) or noncheckers (n = 50) on the basis of their responses to the Checking subscale of the Maudsley Obsessional-Compulsive Inventory (MOCI). DSM-III-R disorders were assessed on the basis of responses to the Diagnostic Interview Schedule, Version III Revised (DIS-III-R), administered by trained, lay interviewers, blind to Ss' checking status. Checkers, compared to noncheckers, were significantly more likely to meet lifetime diagnostic criteria for Major Depressive Episode, Drug Abuse/Dependence, and Social Phobia. Analysis of a subsample (n = 74) selected on the basis of the consistency of responses to the MOCI across two administrations replicated the above effects, with two exceptions: (1) checkers were more likely to meet criteria for Obsessive Compulsive Disorder than were noncheckers, and (2) for males, but not females, Simple Phobia was more prevalent among checkers than among noncheckers. These findings extend our previous work by demonstrating that 'nonclinical' checking behavior is associated with a broad range of psychological syndromes and may, in fact, be more strongly associated with other disorders than it is with Obsessive Compulsive Disorder in a nonclinical sample.     

Effects of imaginal exposure to feared disasters in obsessive-compulsive checkers

The combined effects of imaginal exposure to feared catastrophes and in vivo exposure to external stimuli were compared with the effects of in vivo exposure alone in 15 obsessive-compulsives with checking rituals. The first group received 90 min of uninterrupted exposure in imagination, which concentrated mainly on disastrous consequences, followed by 30 min of exposure in vivo to stimuli-situations which triggered rituals. The second group was given 2 hr of exposure in vivo only. Both groups were prevented from performing rituals. Treatment consisted of 10 daily sessions within a 2 week period.Assessments were conducted before and after treatment and at follow-up ranging from 3 months to 2.5 yr with a mean of 11 months. At post-treatment both groups improved considerably and did not differ. But at follow-up those who received imaginal and in vivo exposure maintained their gains, whereas the group who were treated by exposure in vivo alone evidenced partial relapse on four of the six dependent measures. The results tend to indicate that a closer match between a patient's internal fear model and the content of exposure enhances long term treatment efficacy.     

Negative priming and sequence learning

Three experiments used a novel sequence learning task, in which participants responded to changes in location of one visual stimulus whilst ignoring another. Experiment 1 demonstrated negative priming effects in this task, in that responses to individual sequence elements were disrupted when the attended stimulus (e.g., red asterisk) appeared at the location taken by the unattended stimulus (e.g., blue asterisk) on the immediately preceding trial. Experiments 2 and 3 found that negative priming effects extended beyond sensitivity to individual items, suggesting that people may be able to learn about sequential features of ignored events as well as about single events in isolation. The results are discussed in relation to current theories of negative priming.     

Negative priming and stimulus-response compatibility

The subjects in this study made incongruent naming responses to words and pictures that were presented on alternate trials (e.g., say “car” toBIKE). Their response time was longer if the correct response for the current trial was the name of the stimulus presented on the preceding trial, as compared with a control condition. These results suggest that the tendency to produce the (congruent) name of the stimulus is automatically activated and then inhibited. The “negative priming” effects appeared stronger for words where pictures were primes than for pictures where words were primes. The implications of these results for negative priming and stimulus-response compatibility are discussed.     

Negative priming without ignoring

Negative priming is conventionally defined by slowed responses to a target item that appeared previously as a distractor. As a result, it is widely assumed that negative priming is caused by an act of ignoring. Three experiments are reported in which novel abstract shapes were studied with either “shallow” or “deep” encoding instructions. This study phase was followed by asame-different discrimination task similar to that employed by DeSchepper and Treisman (1996). Same-different discrimination was slower for old than for new target shapes, and this negative priming effect depended on the difficulty of the discrimination task. The results suggest that negative priming may not be caused by the ignoring of a prime stimulus.     

Negative priming reduces affective ratings

The mere exposure effect is the commonly observed increase in pleasantness ratings of stimuli that have been given prior exposure. According to the fluency attribution account of the mere exposure effect, repeated presentations of a stimulus lead to increased ease of processing, which in turn is attributed to pleasantness. If so, processing fluency manipulated by means other than repetition should influence liking. In the present experiment, processing fluency was manipulated using a negative priming procedure, and its influence on affective judgement was examined. Previously ignored stimuli were responded to slower (negative priming) and were rated as less pleasant than controls. It was concluded that decreased processing fluency decreases liking of previously ignored stimuli.     

Negative priming by rotated objects

Previous work has found that repeated exposure to ignored rotated objects is insufficient to allow the formation of orientation-invariant representations (Murray, 1995b). In this study, the negative priming paradigm was used to examine whether the identity of ignored rotated objects was encoded. Subjects were briefly presented with a prime followed by a probe display. One of the two overlapping drawings of objects in each display was selected for further processing, and the other was ignored. In one condition, the ignored objects were upright; in another, they were rotated 240°; and in a final condition, subjects repeatedly named the 240° objects prior to experiencing them as ignored objects in the priming task. Naming latency for the attended probe was slower when it was semantically related to the ignored prime in all conditions. The results suggest that unattended rotated objects are processed to a level of representation that is at least categorical.     

Negative priming without probe selection

Responses to an object may be slower or less accurate if that object shares attributes with a recently ignored object(negative priming). Some studies have found negative priming only if the probe trial required selection against a distractor stimulus. In the present experiment, subjects responded to the location of a target (O), ignoring a distractor (X) if it appeared in another location. Reaction time was slower to probe targets that appeared in the same location as the prime distractor, regardless of whether or not the probe target was accompanied by a distractor.     

Negative priming with masked distractor-only prime trials: awareness moderates negative priming

The literature yields inconsistent evidence for negative priming (NP) following masked distractor-only prime trials. We contrast two different hypotheses on the inconsistent findings: one - which is most compatible with the temporal discrimination theory - that relates the sign of priming effects to the absence vs. presence of prime awareness and one -which is most compatible with the inhibition and episodic retrieval accounts - that relates the sign of priming effects to the prime event being categorized as a to-be-attended vs. to-be-ignored event. In two experiments, it turned out that participants' awareness of the masked stimuli caused the different results (with participants being not aware of the primes showing NP), whereas the factor prime color = probe target color vs. prime color = probe distractor color (i.e., the prime contains the to-be-attended vs. the to-be-ignored signal) did not moderate NP. These findings are discussed with regard to theories of negative priming and the debate on conscious vs. unconscious perception.     

Negative priming depends on ease of selection

Negative priming effects have been offered as evidence that distractor stimuli are identified. We conducted two experiments to determine if such effects occur even when it is easy to discriminate target from distractor stimuli. In Experiment 1, we found the usual negative priming effect when target and distractor positions varied from trial to trial, but not when these positions remained fixed. Experiment 2 extended these results to a situation where the ease of selection varied only in the prime display. These findings argue that irrelevant inputs can be filtered out prior to stimulus identification under certain circumstances and therefore pose problems for strict late selection theories.     

Negative priming from activation of counting and addition knowledge

In two experiments, subjects were presented with digit pairs (e.g., 32) and asked to respond to the rightmost number. Negative priming, that is, slowed processing, was evident when the rightmost number was a counting-string (e.g., 43 following 12) or addition-sum (e.g., 65 following 32) associate of the number pair from the preceding trial. The studies are the first to demonstrate negative priming with counting and arithmetical memory representations and suggest the obligatory activation of these representations with the presentation of number pairs. The results are also consistent with the view that negative priming often occurs at the semantic level. Received: 15 February 2000 / Accepted: 8 June 2000     

Negative priming with numbers: No evidence for a semantic locus

Selective attention has been studied extensively using the negative priming (NP) paradigm. An important issue regards the representational level at which NP occurs. We investigated this issue by using numbers as stimuli. Because numbers have a well-defined semantic organization, which can be clearly measured by means of the distance effect, they are very suitable for testing the assumption that NP is situated at a central semantic level. Four experiments are presented in which the numerical distance between prime distractor and probe target was manipulated. The task was magnitude comparison. Target and distractor were defined on the basis of colour. In Experiment 1, all numbers were presented in Arabic format; NP was observed only with identical prime distractor and probe target, and no distance-related NP was observed. This could not be explained by a decay of inhibition since in Experiment 2 similar results were obtained with a shortened response-to-stimulus interval. Experiment 3 showed that these observations also hold for numbers presented verbally. Nevertheless, a cross-notational experiment with Arabic prime and verbal probe (Experiment 4) revealed no NP whatsoever and excluded the possibility that the absence of distance-related negative priming was the result of a fine-tuned inhibitory mechanism operating at the semantic level. The results are considered in the light of current theories of negative priming.     

Negative priming depends on prime-probe similarity: Evidence for episodic retrieval

It is well established that requiring a person to respond to a recently ignored object in a visual selection task leads to slower responding (i.e., negative priming). In the present experiment, subjects identified target letters flanked by incompatible distractor letters on prime and probe displays. Prime display distractors appeared as the target letter on one third of subsequent probe displays. We manipulated stimulus strength by means of intensity contrast between letter displays and their background. Displays were presented with either high contrast (white against a black background) or low contrast (dark gray against a black background). The important finding was that negative priming was maximal when prime and probe displays shared the same intensity contrast. These results suggest that greater similarity between prime and probe displays results in improved retrieval of prime display information. The results provide strong support for an episodic retrieval account of negative priming.     

Interaction of task readiness and automatic retrieval in task switching: Negative priming and competitor priming

When subjects switch between tasks, performance is slower after a task switch than after a task repetition, even when preparation time is long. We report two experiments that support the idea that a large part of these residual task shift costs can be due to stimulus-cued retrieval of previous task episodes. We demonstrate that there are two different factors at work: (1) facilitation of response to the current distractor stimulus, appropriate to the previously relevant, competing task (competitor priming), and (2) impaired processing of previously suppressed responses (negative priming). Negative priming was contingent on the size of the stimulus set, suggesting that distractor suppression comes into effect only if the distractors are highly activated. Importantly, both types of interference interacted with task readiness: Whereas in the nondominant task (picture naming), switch and nonswitch trials were equally affected, the dominant task (word reading) showed priming effects on switch trials only. Thus, the retrieval of previous processing episodes has a selective impact on situations in which task competition is high.     

Negative identity priming is contingent on stimulus repetition

Five experiments demonstrate that negative identity priming is contingent on stimulus repetition. In ignored repetition conditions, priming was initially positive and became negative as the number of repetitions increased. Moreover, it was repetition as a target, not as a distractor, that was critical for negative priming. The effects of repetition were general: They were found with both naming and same-different paradigms, verbal and pictorial material, familiar and unfamiliar stimuli, and vocal and manual responses. Findings support an activation-based model of negative priming (G. B. Malley & D. L. Strayer, 1995) and are problematic for the episodic retrieval model of negative priming (W. T. Neill & L. A. Valdes, 1992). Finally, the experiments did not replicate B. DeSchepper and A. Treisman's (1996) reported negative priming with nonrepeated novel shapes.     

Negative mood state impairs false memory priming when problem-solving

The aim of this study was to investigate the effect of emotional mood states on the ability to create effective primes using the recently developed false memory priming paradigm. A negative or positive mood state was induced before Deese/Roediger–McDermott (DRM) list presentation. A further control group experienced no mood induction. Participants were then presented with Compound Remote Associate Task (CRAT) problems, half of which had been primed by the previous DRM lists whose critical lure was the solution to the CRAT problem. The results of this study showed that induction of a negative mood state not only impaired recall of critical lures but also diminished their effectiveness as primes for solving CRAT problems. In contrast, for both positive mood and control conditions, the false memory priming advantage was evident, with a higher proportion of primed problems solved in comparison to those not primed. Findings are discussed in relation to the role of affect on semantic activation and the adaptive consequences of false memories.     

Negative priming insame-different matching: Further evidence for a central locus of inhibition

Responses to recently ignored information may be slower or less accurate than responses to information not recently encountered. Such negative priming effects imply that the mechanism of selective attention operates on unattended, as well as attended, information. In the present experiment, subjects judged the second and fourth letters of five-letter strings (e.g., BABAB) as “same” or “different.” Responses were slower when a target letter was identical to the distractors presented in the immediately preceding trial. This effect did not depend on which response was required on the current or preceding trial. The results suggest that ignored information is functionally disconnected from the response system as a whole, rather than from a specific response.