Repeated checking causes memory distrust

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Abstract

This paper attempts to explain why in obsessive-compulsive disorder (OCD) checkers distrust in memory persists despite extensive checking. It is argued that: (1) repeated checking increases familiarity with the issues checked; (2) increased familiarity promotes conceptual processing which inhibits perceptual processing; (3) inhibited perceptual processing makes recollections less vivid and detailed and finally; (4) reduction in vividness and detail promotes distrust in memory. An interactive computer animation was developed in which participants had to perform checking rituals on a virtual gas stove. Two separate experiments were carried out with n=39 (Experiment I) and n=40 (Experiment II) healthy participants. In both studies, the control group and the experimental group were given the same pre-test and post-test on the virtual gas stove. In between, the experimental group engaged in ‘relevant checking’, i.e. checking the gas stove, while the control group engaged in ‘irrelevant checking’, i.e. checking virtual light bulbs. In both experiments there were powerful effects of repeated ‘relevant checking’: while actual memory accuracy remained unaffected, the vividness and detail of the recollections were greatly reduced. Most pertinently, in both experiments relevant checking undermined confidence in memory. No such effects were observed in the control group. One might argue that the pre-test/post-test design may have made the control group anticipate a memory assessment at the post-test and that this artifact made them relatively alert producing memory confidence at post test that was artificially high. A third experiment was carried out (n=2×20) in which no pre-test was given while, other than that, Experiment III was identical to the first two experiments. Results confirmed earlier findings: compared to the irrelevant checking control group, recollections in the relevant checking group were non-vivid, non-detailed while confidences in memory was low. The theory and data suggest an answer to the question ‘why memory distrust persists despite repetitive checking’. In people who check extensively, memory distrust may persist as a result of repetitive checking. OCD checking may be motivated by the wish to reduce uncertainty, but checking appears to be a counter-productive safety strategy. Rather than reducing doubt, checking fosters doubt and ironically increases meta-memory problems.

Introduction

Obsessive-compulsive disorder (OCD) patients with checking problems repeatedly check whether previous efforts to prevent harm were carried out appropriately. Checking by OCD patients is repetitive; checkers tend not to check once or twice, but (much) more often. Why are one or two checks not enough to reassure the patient? The cognitive theory of OCD as formulated by Salkovskis (1985) explains why patients feel urged to check. OCD patients are held to have an exaggerated sense of responsibility to prevent future harm. By checking, patients may try to prevent their being held responsible for future catastrophes. Experimental evidence underscores that perceived responsibility in OCD checkers is truly causal to their checking urges. That is, deliberately increasing or decreasing perceived responsibility in OCD checkers produces immediate increases or decreases in the urge to check (Lopatka & Rachman, 1995). Note that if personal responsibility for potential danger is involved, checking is a common strategy to prevent calamities. Airplane pilots, for instance, check their gear before landing (Griez, 2001). While cognitive theory explains the occurrence of checking urges, it does not readily explain the persistence of doubt after checking. Pilots check once. Why is once not enough for patients?

An answer is suggested by mnestic deficit theories. It is assumed that checkers suffer from memory deficits about, among other things, previous actions (Tallis, 1995). Inability to recall a previous action would motivate the checker to check the action and its results. But checking itself is an action that could be subject to the same memory deficit, urging the patient to check again, et cetera. While some researchers reported that OCD patients performed worse than healthy controls on standard memory tasks (for an overview, see Tallis, 1997), other researchers did not find such between-group differences (MacDonald, Antony, Macleod and Richter, 1997, McNally and Kohlbeck, 1993). Moreover, mild memory underperformance was also observed with anxious subjects who did not suffer from OCD (Asmundson, Stein, Larsen and Walker, 1994/1995, Lucas, Telch and Bigler, 1991). Furthermore, doubting in OCD is highly domain-specific and memory deficit theory alone does not explain the domain specificity of doubt. Finally, under conditions of high responsibility, OCD checkers showed a positive memory bias (Radomsky, Rachman, & Hammond, 2001) and this is hard to reconcile with the notion of a ‘mnestic deficit’.

Thus, it is far from evident that OCD checkers suffer from a general memory deficit. What is clear, however, is that OCD checkers have low confidence in their memories (Hermans et al., 2002, Rachman, 1973) and that they therefore suffer from a ‘meta-memory’ problem. Provided that neither cognitive theory nor mnestic deficit theory provides a strong account for low confidence in recollections about checking, how should the latter be explained?

Confidence in recollections depends, among other things, on their vividness and detail (Wolters, 2000). In their turn, vividness and detail are influenced by the familiarity of the recollected event: the more familiar the event, the less detailed and vivid the recollection (Johnston and Hawley, 1994, Roedinger, 1990). The reason why familiarity reduces vividness/detail is that with increased familiarity processing priority is increasingly given to higher level semantic aspects and this inhibits the processing of lower level perceptual elements like colors, shapes, etc. It is this inhibition of perceptual processing that will render the recollection of familiar episodes less vivid and less detailed. In sum, with increased familiarity the person will prioritize processing semantic aspects at the expense of perceptual aspects and as a result vividness and detail of the recollection decrease. This decreased vividness/detail undermines memory confidence about any special case from a class of familiar events.

The more an OCD patient checks the more familiar the checking gets. The latter should make the recollection less vivid/detailed and this should reduce confidence in memory about the checking episode. This provides a hypothetical answer to the question why OCD checkers distrust their memory after checking. Briefly put, repeated checking causes memory distrust. Repeated checking by OCD patients may be motivated by the wish to obtain certainty, but checking will, ironically, breed doubt instead of confidence1.

Two predictions were derived from this hypothesis. First, relative to an appropriate control group, repeated checking of the type shown by OCD checkers should in itself decrease vividness and detail of recollections of the last checking operation. Second, repeated checking will reduce confidence in memory about recently checked actions.

Apart from vividness, detail and confidence, two other memory aspects were assessed. First, objective memory accuracy was assessed with a forced choice item. OCD seems to be characterized by meta-memory problems rather than problems in actual accuracy. If repeated checking reduced memory confidence while leaving memory accuracy intact, this would add to the clinical validity of the study. Second, while Rachman (2002), just like the present authors, proposed that checking reduces confidence in the recall of checking, he expressed doubt as to whether checking would likewise reduce confidence in the outcome of checking (Rachman, 2002, p. 6). On clinical and theoretical grounds it is not clear what to expect here and it was decided to settle the issue empirically.

After the present experiments were carried out, effects of repeated exposures to specific stimuli on meta-memory were reported (Tolin et al., 2001). Fourteen OCD patients were exposed six times to idiosyncratically selected safe stimuli (e.g. a clean coin), to unsafe stimuli (e.g. a dirty coin) and neutral stimuli (e.g. a flower). There were two groups of yoked controls: non-anxious controls and anxious controls. Each member of the control groups was exposed to the same stimuli as one particular OCD patient. For each of the six 10-s exposures the stimuli were re-arranged on a table, and after each exposure memory confidence was measured (“how confident are you that you really saw….”?). The main finding was that with regard to the unsafe objects, the OCD patients became less confident over the course of the six trials. The authors took this to suggest that the worsening of meta-memory for unsafe objects over trials is specific to OCD. Note, however, that the control participants were not exposed to stimuli that for them counted as unsafe. Therefore we feel the Tolin et al. study is silent about differences between OCD and other groups. From the present perspective, reduced memory confidence after repeated exposure (increased familiarity) to the same stimuli is a normal cognitive process. While Tolin et al. do not discuss the finding, it is of current interest is that even with the very few (6) and very short (10 s) exposures, for all three types of stimuli (safe/unsafe/neutral) there were small but significant main effects of trial on confidence: as exposure increased, memory confidence decreased. This is exactly what follows from the perspective developed in the present paper. More and more elaborate exposure of the type provided by extensive checking may be expected to yield stronger effects.

To test the present hypothesis an interactive computer task was developed in which participants were asked to check, with a PC mouse, whether three out of six gas knobs from an animated gas-stove with six gas rings were off. After this first checking episode, objective memory accuracy (“What knobs did you check?”), vividness and detail of the recollection, memory confidence (“How confident are you that you checked the knobs that you just indicated?”) and outcome confidence (“How confident are you that all rings are turned off?”) were assessed. The ‘irrelevant checking group’, i.e. the control group, then checked animated light bulbs 20 times. The ‘relevant checking group’, i.e. the experimental group, checked the same gas stove that was used for the pre-test 20 times. Then, at post-test, participants in both groups were asked to check the gas stove again and the same items from the pre-test were scored. The hypothesis to be tested implies that the memory distrust of OCD patients is a normal result of repeated checking. Therefore, the predictions were tested in samples of healthy participants.

Section snippets

Participants

Twenty-seven female and 12 male undergraduates participated. Their mean age was 21 years (SD=2.4) and they were paid a small remuneration.

Procedure and computer animation

Participants were tested in a dimly lit and sound-attenuated laboratory room where they sat at a table with a PC. During the experimental task, the experimenter observed the participants through a one-way mirror. The questions to be answered were typed on booklets and were handed out by the experimenter.

The animation started with a training phase during which

Method

There were 40 participating students, 33 females, the mean age was 21 years (SD=1.6) and participants were paid for their co-operation.

Method

The training phase was identical to that of Experiment II while the rest of the experiment was identical to that of Experiments I and II, the only exception being that no pre-test was administered. The dependant measures were identical to those of the earlier two experiments: memory accuracy, vividness and detail of recollections, confidence in memory and outcome confidence. There were 40 participants (23 female; mean age 20.2 years) who were paid for participation.

Results

(1) Accuracy of memory after

General discussion

The question addressed was why OCD checkers remain uncertain despite repeated checking. The hypothetical answer was that OCD checkers remain uncertain as a result of repeated checking. We found that displaying OCD-like checking behavior resulted in reduced vividness/detail of recollections and, while actual memory accuracy was unaffected by checking, repeated checking was sufficient to induce profound memory distrust. The findings were robust and observed in three independent experiments.

Acknowledgements

Acknowledgements and thanks to Neeltje Wiersma and Marit Voets for carrying out the experiments; to Theo van Aerts and Bert Hoekzema for developing the software for the interactive computer simulation that was used in the experiments.

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