The influence of suggestibility on memory

We provide a translation of Binet and Henri's pioneering 1894 paper on the influence of suggestibility on memory. Alfred Binet (1857-1911) is famous as the author who created the IQ test that bears his name, but he is almost unknown as the psychological investigator who generated numerous original experiments and fascinating results in the study of memory. His experiments published in 1894 manipulated suggestibility in several ways to determine effects on remembering. Three particular modes of suggestion were employed to induce false recognitions: (1) indirect suggestion by a preconceived idea; (2) direct suggestion; and (3) collective suggestion. In the commentary we suggest that Binet and Henri's (1894) paper written over 115 years ago is still highly relevant even today. In particular, Binet's legacy lives on in modern research on misinformation effects in memory, in studies of conformity, and in experiments on the social contagion of memory.     

Levels of processing: a view from functional brain imaging

This paper briefly reviews two central assumptions of the levels-of-processing framework in the light of findings from recent PET and fMRI studies: First, to address the suggestion that memory traces can be seen as records of analyses carried out for the purposes of perception and comprehension, studies on encoding-retrieval overlap in brain activation patterns are considered. Second, to address the suggestion that deeper, more semantic, processing results in more durable traces, studies of how encoding activity relates to processing depth and subsequent memory performance are examined. The results show that some of the sensory regions that are activated during initial perception are subsequently reactivated during retrieval, and activity in frontal and medial-temporal brain regions is related to depth of processing and level of memory performance. Collectively, these results provide support for central components of the levels framework.     

暗示条件下的错误记忆研究概述

心理学家通过采用事后提供误导信息的方法以及临床治疗中的催眠、想象等暗示性程序发现的记忆歪曲和记忆移植现象,说明记忆的改变并不局限于对经历的或记得的情节的某方面的修改,它还能创造虚假的自传性事件记忆。     

Levels of processing: A view from functional brain imaging

This paper briefly reviews two central assumptions of the levels-of-processing framework in the light of findings from recent PET and fMRI studies: First, to address the suggestion that memory traces can be seen as records of analyses carried out for the purposes of perception and comprehension, studies on encoding-retrieval overlap in brain activation patterns are considered. Second, to address the suggestion that deeper, more semantic, processing results in more durable traces, studies of how encoding activity relates to processing depth and subsequent memory performance are examined. The results show that some of the sensory regions that are activated during initial perception are subsequently reactivated during retrieval, and activity in frontal and medial-temporal brain regions is related to depth of processing and level of memory performance. Collectively, these results provide support for central components of the levels framework.     

Posthypnotic amnesia for a first romantic relationship: Forgetting the entire relationship versus forgetting selected events

This experiment investigated the impact of suggestion focus on posthypnotic amnesia (PHA) for memories of a first romantic relationship. During hypnosis, high and low hypnotisable participants recalled specific memories from this period in response to 10 cue phrases (Elicitation). They then received a PHA suggestion that targeted either the entire period or specific memories from that period. Participants' explicit memory was indexed by cued recall after PHA was administered (memories recalled to "old" and "new" cues; Recall 1) and after it was cancelled (Recall 2). A social judgement task indexed dissociations between implicit and explicit memory. PHA had the greatest impact on highs', but not lows', memory performance (in terms of memories recalled to old cues, recall latency, and qualitative memory ratings) when the suggestion targeted the entire period rather than specific events. We discuss these findings in terms of the parameters of PHA's influence on memory, its value for exploring the nature and structure of autobiographical memory, and its utility as a laboratory analogue of functional amnesia.     

Changing beliefs and memories through dream interpretation

Autobiographical memory is malleable, but how much can we change people's beliefs and memories about the past? We approached this question with a method designed to supply subjects with a highly personalized suggestion about what probably happened in their childhood. In the current study, one group of subjects (the ‘Dream’ subjects) had their dreams interpreted to indicate that they had experienced a critical childhood event (e.g. being harassed by a bully) before the age of 3. Relative to control subjects who did not receive personalized suggestion, the Dream subjects were more likely to increase their belief that they had the critical experience, and approximately half of these also produced concrete memory reports. These findings are discussed in terms of their implications for autobiographical memory, and also for psychotherapy practice. Copyright © 1999 John Wiley & Sons, Ltd.     

Exposure to suggestion and creation of false auditory memories

The experiment investigated the possibility of creating false auditory memory through exposure to suggestion. Research by Loftus and others has indicated that, through suggestion, false memories can be created. Participants viewed a short film and were given a 9-item questionnaire. Eight questions were used as filler while one question asked respondents to recall a phrase one character had said. Although the character actually said nothing, 23 of 30 respondents recalled having heard him speak and specifically recalled his words. This statistically significant result shows that auditory memories can also be created.     

Posthypnotic amnesia for a first romantic relationship: Forgetting the entire relationship versus forgetting selected events

This experiment investigated the impact of suggestion focus on posthypnotic amnesia (PHA) for memories of a first romantic relationship. During hypnosis, high and low hypnotisable participants recalled specific memories from this period in response to 10 cue phrases (Elicitation). They then received a PHA suggestion that targeted either the entire period or specific memories from that period. Participants' explicit memory was indexed by cued recall after PHA was administered (memories recalled to “old” and “new” cues; Recall 1) and after it was cancelled (Recall 2). A social judgement task indexed dissociations between implicit and explicit memory. PHA had the greatest impact on highs', but not lows', memory performance (in terms of memories recalled to old cues, recall latency, and qualitative memory ratings) when the suggestion targeted the entire period rather than specific events. We discuss these findings in terms of the parameters of PHA's influence on memory, its value for exploring the nature and structure of autobiographical memory, and its utility as a laboratory analogue of functional amnesia.     

Validating reports of poor childhood memory

Recent evidence indicates that judgements about the quality of one's own childhood memory can be influenced experimentally, for example by manipulating ease of retrieval. This has led to the suggestion that judgements of poor memory made by clients in therapy may not be reliable. We therefore investigated whether individuals who judge themselves to have poor memory for their childhood do in fact score worse on a standardized test of autobiographical memory. Matched groups of individuals reporting poor and normal memory for childhood were administered the Autobiographical Memory Interview. Consistent with a previous study of neurological patients, subjective judgements were associated with performance on both personal semantic memory and autobiographical incident memory. Copyright © 2002 John Wiley & Sons, Ltd.     

Placebo-mediated, Naloxone-sensitive suggestibility of short-term memory performance

Physiological studies of placebo-mediated suggestion have been recently performed beyond their traditional clinical context of pain and analgesia. Various neurotransmitter systems and immunological modulators have been used in successful placebo suggestions, including Dopamine, Cholecystokinin and, most extensively, opioids. We adhered to an established conceptual framework of placebo research and used the μ-opioid-antagonist Naloxone to test the applicability of this framework within a cognitive domain (e.g. memory) in healthy volunteers. Healthy men (n=62, age 29, SD=9) were required to perform a task-battery, including standardized and custom-designed memory tasks, to test short-term recall and delayed recognition. Tasks were performed twice, before and after intravenous injection of either NaCl (0.9%) or Naloxone (both 0.15 mg/kg), in a double-blind setting. While one group was given neutral information (S-), the other was told that it might receive a drug with suspected memory-boosting properties (S+). Objective and subjective indexes of memory performance and salivary cortisol (as a stress marker) were recorded during both runs and differences between groups were assessed. Short-term memory recall, but not delayed recognition, was objectively increased after placebo-mediated suggestion in the NaCl-group. Naloxone specifically blocked the suggestion effect without interfering with memory performance. These results were not affected when changes in salivary cortisol levels were considered. No reaction time changes, recorded to uncover unspecific attentional impairment, were seen. Placebo-mediated suggestion produced a training-independent, objective and Naloxone-sensitive increase in memory performance. These results indicate an opioid-mediated placebo effect within a circumscribed cognitive domain in healthy volunteers.     

Blocking of human causal learning involves learned changes in stimulus processing

Several theories of associative learning propose that blocking reflects changes in the processing devoted to learning about cues. The results of the only direct test of this suggestion in human learning (Kruschke & Blair, 2000) could equally well be explained in terms of, among others, interference in learning or memory. The present study tested this suggestion in a situation in which processing-change and interference accounts predict opposing results. Results support the idea that blocking in human learning can reflect a change in processing of the cues involved.     

Blocking of human causal learning involves learned changes in stimulus processing

Several theories of associative learning propose that blocking reflects changes in the processing devoted to learning about cues. The results of the only direct test of this suggestion in human learning (Kruschke & Blair, 2000) could equally well be explained in terms of, among others, interference in learning or memory. The present study tested this suggestion in a situation in which processing-change and interference accounts predict opposing results. Results support the idea that blocking in human learning can reflect a change in processing of the cues involved.     

Absolut memory distortions: alcohol placebos influence the misinformation effect

Can the simple suggestion that you have consumed alcohol affect your memory for an event? Alcohol placebos affect social behaviors but not nonsocial ones, and have not previously been shown to affect memory. We investigated the effect of alcohol placebos using materials that revealed both the social and the nonsocial influences of memory Subjects drank plain tonic water, but half were told it was a vodka and tonic; then all subjects took part in an eyewitness memory experiment. Subjects who were told they drank alcohol were more swayed by misleading postevent information than were those who were told they drank tonic water, and were also more confident about the accuracy of their responses. Our results show that the mere suggestion of alcohol consumption may make subjects more susceptible to misleading information and inappropriately confident. These results also provide additional confirmation that eyewitness memory is influenced by both nonsocial and social factors.     

Strategies for Generating Multiple Instances of Common and Ad Hoc Categories

Three experiments explored word/name homographs (GARLAND-musical star/ wreath of flowers) to determine the extent to which presenting them for study as surnames or as content words affected memory on immediate retest. Implicit and explicit measures were taken. Implicit memory occurred reliably on all variants of this task. Names were better remembered than words when the forename was presented as a cue and subjects were asked to generate a surname. This finding conforms with the suggestion (Bredart, Valentine, Calder, & Gassi, 1995) that there is a dedicated name-output stage in the memory system, and suggests that this can be activated under some implicit memory conditions. Further experiments showed that this name advantage was not upheld under other (word but not name) cued-recall conditions. Under these conditions, implicit memory is sensitive to the perceptual rather than the contextual conditions of presentation.     

Physiological, psychological and behavioral consequences of activating autobiographical memories

Activating an autobiographical memory for a specific childhood event can have immediate and robust physiological, psychological, and behavioral consequences. The target behavior was public speaking, a vital skill about which many people are socially anxious. In this study, it was suggested to subjects that they had a positive public speaking experience in early childhood; they then thought about and retrieved details of this true childhood memory. Compared to a control condition in which a different suggestion was made, subjects in the treatment group exhibited superior public speaking performance on the Trier Social Stress Test (TSST). Further, physiological measures of cortisol and a self-report measure of anxiety (STAI-S) reflected a significantly smaller increase in anxiety from before to after the TSST in the treatment than control condition. Activating autobiographical memory for an event increases the accessibility of that memory and consequently affects performance on related behaviors.     

Effects of mothers’ conversation style and receipt of misinformation on children's event reports

Can memory sharing conversations with mothers lead to errors in children's event memory when mothers are exposed to misinformation about what their children experienced and does this effect vary as a function of maternal memory-sharing style? Mothers were exposed to a false suggestion about a non-shared event and then discussed that event with their children. When later interviewed, those children whose mothers were provided this misinformation were likely to wrongly report experiencing activities consistent with the maternal suggestion and embellish their reports of these activities with elaborative detail. Moreover, children whose mothers spoke in a highly elaborative manner were more likely to recall occurrences in line with the maternal suggestion and provided more fictitious narrative detail describing non-occurring-but-suggested information than did children whose mothers used a less elaborative style. These findings suggest that when mothers hold false beliefs about a non-shared event, an elaborative maternal style is associated with an increase in children's false reports reflecting maternal beliefs.     

Retrieval time as a function of memory ensemble size

A direct test was performed of Oldfield's (1966) derivation of the relationship between naming response latency and memory ensemble size. The results confirmed Oldfield in every particular. Further, the results support Sperling's (1967) suggestion of a recognition buffer-memory mechanism between the initial stimulus-encoding stage and the long-term memory stage of human information processing.     

Recognition instructions and recognition practice can alter the confidence--response time relationship

Three face-recognition experiments examined how instructions for a recognition test (e.g., emphasize speed or emphasize accuracy) can impact the confidence-response time relationship for episodic memory reports. In all 3 experiments, the confidence-response time correlation was smaller when participants were told to speed up their responding rate, which suggests that participants in these conditions relied less on the artificially compressed response times in forming their confidence judgments than they would under "normal" circumstances. Also, recognition practice before the final memory test eliminated the effect of the recognition instruction manipulation. These results support J. S. Shaw's (1996) suggestion that witnesses rely in part on the fluency of their memory reports when generating confidence judgments, and these findings have important implications for understanding the relationships among witness confidence, accuracy, and response time.     

Personalized and not general suggestion produces false autobiographical memories and suggestion-consistent behavior

Suggesting false childhood events produces false autobiographical beliefs, memories and suggestion-consistent behavior. The mechanisms by which suggestion affects behavior are not understood, and whether false beliefs and memories are necessary for suggestions to impact behavior remains unexplored. We examined the relative effects of providing a personalized suggestion (suggesting that an event occurred to the person in the past), and/or a general suggestion (suggesting that an event happened to others in the past). Participants (N=122) received a personalized suggestion, a general suggestion, both or neither, about childhood illness due to spoiled peach yogurt. The personalized suggestion resulted in false beliefs, false memories, and suggestion-consistent behavioral intentions immediately after the suggestion. One week or one month later participants completed a taste test that involved eating varieties of crackers and yogurts. The personalized suggestion led to reduced consumption of only peach yogurt, and those who reported a false memory showed the most eating suppression. This effect on behavior was equally strong after one week and one month, showing a long lived influence of the personalized suggestion. The general suggestion showed no effects. Suggestions that convey personal information about a past event produce false autobiographical memories, which in turn impact behavior.