The Effects of Suggested Invisibility on Memory

Date

2015-01-05

Authors

Azad, Tanjeem

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Abstract

Erroneous suggestions can add to or contradict people’s memories for previously witnessed event details. Researchers have also investigated a different kind of erroneous suggestion in which details from a target event that had actually been witnessed are erroneously suggested to not have transpired in the event. This phenomenon is referred to as the suggested invisibility effect. Previous research examining suggested invisibility has not thoroughly examined the mechanisms underlying the effect. That is, does not reporting previously witnessed event details reflect demand characteristics or genuine memory impairments? The current dissertation research was motivated by such questions. In a newly developed paradigm, 5 experiments examined suggested invisibility and its accompanying subjective memory. Subjects watched a crime video and 2 days later read three hand-written simulated witness testimonies. Each testimony (a) stated that two event details were not visible in the video (though they in fact were clearly displayed) and (b) mentioned two other details in broad generic terms. Subjects then completed a final memory test to assess their memory for the original crime video. Experiment 1 produced the basic effect, showing that subjects were significantly less likely to report witnessed details when they had been erroneously suggested to not have been visible compared to control details. Experiment 2A was conducted to further examine the basis of suggested invisibility, however, many subjects expressed disbelief in the testimonies and this resulted in null effects. Subsequent experiments enhanced the plausibility of the testimonies. Experiment 2B amended the rationale to subjects for reading the lengthy testimonies and replicated the suggested invisibility effect; Experiment 3 embedded suggestions of invisibility in response to cued-recall questions rather than in lengthy narratives; and, Experiment 4 presented subjects with a transcript of an interview between a witness and an experimenter. In both Experiments 3 and 4, robust effects of suggested invisibility were only attained with naïve subjects who claimed to not have been suspicious of the experimental manipulation. When suggested invisibility was observed subjects’ confidence levels were similar to that of control details, suggesting that sometimes subjects were genuinely confident in not having witnessed previously seen details. Collectively, these findings support the idea that memories can be swayed in the direction of erroneous suggestions that render false reports of not having seen previously witnessed details.

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Keywords

false memory, misinformation effect, suggested invisibility, subjective confidence

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