Interrogative suggestibility and its relationship with personality, perceptual defensiveness and extraordinary beliefs

This study looks at the relationship between interrogative suggestibility and personality as measured by the EPQ, perceptual defensiveness and belief in extraordinary and religious phenomena. Suggestibility was found to correlate significantly with the EPQ L scale, the degree of perceptual defensiveness and belief in witchcraft. The Icelandic translation of the Gudjonsson Suggestibility Scale and the resulting scores were found to be consistent with British norms. This suggests that the GSS can be used cross-culturally.     

Interrogative suggestibility,delayed memory and self-concept

This study investigates the relationship between interrogative suggestibility as measured by the Gudjonsson Suggestibility Scale (GSS) and variables related to memory recall and self-esteem. There were 30 Ss, tested twice 1 week apart. After completing the GSS they were required to fill in a number of Semantic Differential scales relating to the concepts: Myself as I am generally, Myself during the experiment and The experimenter. Ss were generally more suggestible during the second interview when their memory about the context of the interrogation context had deteriorated. The exception was that negative feedback appeared to have most effect on suggestibility and self-esteem the first time it was applied. Self-esteem related to ‘competence’ and ‘potency’ correlated significantly with suggestibility, especially during the first interrogative session. Perceptions of the experimenter were generally not found to be significantly related to suggestibility.     

Interrogative suggestibility and delinquent boys: An empirical validation study

This study has several aims. First, to validate the Gudjonsson Suggestibility Scale (GSS) among delinquent and adolescent boys placed in an assessment and short-term treatment centre. Second, to test the hypothesis that adolescent boys are particularly susceptible to suggestions when they are ‘pressured’ by negative feedback and instructions. Finally, to investigate the hypothesis that suggestibility is related to memory recall and self-esteem. The GSS was administered to 31 boys (ages 11 to 16 yr) who had been independently rated by two teachers on measures of suggestibility and self-esteem. Suggestibility as measured by the GSS was found to correlate significantly with the teachers' ratings of suggestibility, supporting empirically the criterion-related validity of the GSS. Compared with young ‘normal’ adults the boys were no more likely to give in to suggestive questions than the adults, unless their performance was subjected to criticism and negative feedback. The results suggest that deliquent adolescents may be particularly responsive to interpersonal pressure during interrogation. The findings have important implications for police interrogation procedures.     

Dichotic listening and sleep deprivation: vigilance effects

Twelve sleep-deprived and 13 non-deprived Navy cadets were tested with the dichotic listening procedure for effects of sleep deprivation on hemispheric asymmetry and sustained attention. Consonant-vowel syllables were presented to the subjects in three different conditions, a divided (non-forced) attention condition, a forced right ear and a forced left ear attention condition. In the two forced attention conditions the subjects were instructed to focus attention only on the right or left ear stimulus. The results showed an expected right ear advantage for both groups during the non-forced and forced right attention conditions, indicating superior left hemisphere processing. During the forced left attention condition, the sleep-deprived subjects showed no ear advantage at all, while the non-deprived subjects showed an expected left ear advantage. The results are discussed within a theoretical framework of a dual process model, where sleep deprivation disrupts the ability to sustain attention, caused by a temporary failure of the right hemisphere's top-down (instruction-driven) processing to override the left hemisphere's bottom-up (stimulus-driven) processing.     

The effects of sleep deprivation and incentives on human performance

Summary This study explores whether KR (knowledge of results) and reward compensate for the negative joint effects of sleep deprivation and signal degradation in a choice-reaction task. The negative effect of signal degradation on performance was aggravated by sleep loss and time-on-task, whereas KR improved performance, especially when signals were degraded. Reward changed the effects of time-on-task owing to lack of sleep. Performance was also improved by a brief task interruption after 30 minutes' work, with 5 more minutes to go. These results can be interpreted in terms of the performance model of Sanders (1983), which links energetic mechanisms to stages of information processing. A lack of energetic supply from the arousal mechanism to perceptual processing, induced by signal degradation, sleep deprivation, and time-on-task, was effectively counteracted by KR: KR enables the mobilization of effort to compensate for this lack of arousal. The relation between reward and KR is not yet clear. The interruption effect suggests that the influence of time-on-task is not due to loss of arousal, but causes a reallocation of resources by effort.     

The effects of sleep deprivation on the attentional functions and vigilance

The study of sleep deprivation is a fruitful area of research to increase our knowledge of cognitive functions and their neural basis. In the current work, 26 healthy young adults participated in a sleep deprivation study, in which the Attentional Networks Test for Interactions and Vigilance (ANTI-V) was performed at 10a.m. after a night of normal sleep and again at 10 a.m. after 25.5-27.5 h of total sleep deprivation. The ANTI-V is an experimental task that provides measures of alerting, orienting and executive control attentional functions. Compared with previous versions, the ANTI-V includes a vigilance task, more reliable auditory alerting signals, non-predictive peripheral orienting cues, and also a neutral no-cue condition allowing the analysis of reorienting costs and orienting benefits. Thus, new evidence to evaluate the influence of sleep deprivation on attentional functioning is provided. Results revealed differences in both tonic and phasic alertness after sleep deprivation. Vigilance performance was deteriorated, while a warning tone was more helpful to increase participants' alertness, resulting in slightly faster RT and, in particular, fewer errors. The reorienting costs of having an invalid spatial cue were reduced after sleep loss. No sleep deprivation effect on the executive control measure was found in this study. Finally, since no control group was used, particular precautions were taken to reduce the influence of potential practice effects.     

Some components of colour-word interference and their relationship with field dependence

It was suggested that the standard colour-word interference situation involves a number of distinct factors, each of which will contribute to the overall delay. Interference was analysed in terms of the delay associated with particular characteristics of different interfering stimuli; these measures were found to be unrelated, and were thus held to represent distinct components of the interference effect. Field dependence was primarily related to the component which was described as ‘perceptual distraction’.     

The effects of chronic sleep reduction on the performance of cognitive tasks sensitive to sleep deprivation

In four sleep loss experiments we aimed, first, to compare performance during long-term sleep reduction with performance during short-term total sleep deprivation, and second, to measure the effects of both methods of sleep loss on ability to ignore distracting irrelevant stimuli, using a finding embedded figures test (FEFT). Logical reasoning, auditory vigilance and finding embedded figures tasks were shown to be significantly sensitive to one night's sleep deprivation. However, in one sleep reduction study subjects reduced to a mean of 5.2 hours sleep per night for 4 weeks showed no performance deficits on logical reasoning. In a second sleep reduction study subjects reduced to a mean of 4.3 hours sleep per night for 4 nights, and subjects reduced to a mean of 5.3 hours sleep per night for 18 nights, showed no performance deficits on logical reasoning or auditory vigilance, despite their reports of severe increases in subjective sleepiness and reduced concentration. Both these sleep reduction groups, though, did show decrements on the FEFT, which we interpret in terms of dearousal increasing distractibility, which the sleep-reduced subjects could not overcome with effort, as they did with the other tests.     

The effects of repeated experience on children's suggestibility

The effect of suggestive questions on 3- to 5-year-old and 6- to 8-year-old children's recall of the final occurrence of a repeated event was examined. The event included fixed (identical) items as well as variable items where a new instantiation represented the item in each occurrence of the series. Relative to reports of children who participated in a single occurrence, children's reports about fixed items of the repeated event were more accurate and less contaminated by false suggestions. For variable items, repeated experience led to a decline in memory of the specific occurrence; however, there was no increase in susceptibility to suggestions about details that had not occurred. Most errors after repeated experience were intrusions of details from nontarget occurrences. Although younger children and children who were interviewed a while after the event were more suggestible, respectively, than older children and those interviewed soon after the event, repeated experience attenuated these effects.     

The effects of total sleep deprivation on recognition memory processes: A study of event-related potential

This study examined the memorization of information after a night of normal sleep and total sleep deprivation (TSD) by means of event-related potentials (ERPs). We expected a disfacilitatory effect of TSD on memory processing. Eighteen subjects were tested twice in a counterbalanced fashion. During the study session, subjects were presented with unfamiliar face stimuli and asked to memorize them for a subsequent memory test. At the test session, the subjects were presented with the studied faces intermixed with “new” faces and asked to indicate the previously presented stimuli. The N100 was used as a covariate to control for the differences in level of vigilance between the two sessions. Sleep deprivation decreased subjects’ ability to discriminate new from previously studied stimuli and decreased the peak amplitude of the early component (N200) to the decrement of performance. In addition, following TSD the amplitude of the late frontal component (LFC), which is thought to reflect contextual processing, was decreased in covariance with the N100 vigilance component. The amplitude of the late posterior component (LPC/P600) was also reduced but was unrelated to the vigilance component of the ERP. Based on prior studies, this LPC reduction can be interpreted to indicate a decrease in information retrieved after TSD. In summary, a night of TSD decreased the amplitude of the ERPs associated with complex episodic memory task stimuli, affected the frontal cortex during episodic retrieval, and prevented the elaboration process. Furthermore, there was an inability to discriminate what is and what is not in memory, possibly due to less local processing of details.     

The effects of prior knowledge on children's memory and suggestibility

In this study, 5- and 6-year-olds were read a story and asked to recall its details. Two independent factors-prestory knowledge and poststory suggestions-were crossed to examine the effects on children's story recall. The results indicated that prestory social knowledge about the story protagonist as well as academic knowledge relating to the content of the story influenced the accuracy of children's recall immediately after the story presentation. Following the suggestive interview, children reported interviewer-provided social and academic misinformation to a greater extent when the misinformation was consistent with their prior knowledge. In contrast, children were more likely to refute misinformation that contradicted their academic knowledge. These findings are discussed in terms of the mechanisms underlying the knowledge-memory and knowledge-suggestibility linkages.     

Interrogative pressure in simulated forensic interviews: The effects of negative feedback

Much experimental research on interrogative pressure has concentrated on the effects of leading questions, and the role of feedback in influencing responses in the absence of leading questions has been neglected by comparison. This study assessed the effect of negative feedback and the presence of a second interviewer on interviewee responding in simulated forensic interviews. Participants viewed a videotape of a crime, answered questions about the clip and were requestioned after receiving feedback. Compared with neutral feedback, negative feedback resulted in more response changes, higher reported state anxiety and higher ratings of interview difficulty. These results are consistent with Gudjonsson and Clark's (1986) model of interrogative suggestibility. The presence and involvement of a second interviewer did not significantly affect interviewee responding, although trait anxiety scores were elevated when a second interviewer was present. The theoretical and applied implications of these findings are considered.     

Minimizing sleep deprivation effects in healthy adults by differential outcomes

Sleep deprivation reduces vigilance or arousal levels, affecting the efficiency of certain cognitive functions such as learning and memory. Here we assessed whether the differential outcomes procedure (DOP), a learning procedure that has proved useful to ameliorate episodic memory deficits, can also improve memory performance in sleep-deprived participants. Photographs were presented as sample faces. A probe face was then presented for recognition after either short or long delays. In the differential outcomes condition a unique reinforcer followed correct responses. In the non-differential outcomes condition reinforcers were provided in a random manner. The results indicated that the DOP prevented the recognition memory to decrement during the long delay in the control group, replicating previous findings. The sleep-deprived group showed DOP benefits mainly with the short delay, when working memory could be affected by low arousal. These findings confirm that the DOP can overcome impaired recognition memory due to sleep deprivation conditions.     

The impact of sleep deprivation on decision making: a review

Few sleep deprivation (SD) studies involve realism or high-level decision making, factors relevant to managers, military commanders, and so forth, who are undergoing prolonged work during crises. Instead, research has favored simple tasks sensitive to SD mostly because of their dull monotony. In contrast, complex rule-based, convergent, and logical tasks are unaffected by short-term SD, seemingly because of heightened participant interest and compensatory effort. However, recent findings show that despite this effort, SD still impairs decision making involving the unexpected, innovation, revising plans, competing distraction, and effective communication. Decision-making models developed outside SD provide useful perspectives on these latter effects, as does a neuropsychological explanation of sleep function. SD presents particular difficulties for sleep-deprived decision makers who require these latter skills during emergency situations.     

The effects of total sleep deprivation on semantic priming: Event-related potential evidence for automatic and controlled processing strategies

There is general consensus that performance on a number of cognitive tasks deteriorates following total sleep deprivation. At times, however, subjects manage to maintain performance. This may be because of an ability to switch cognitive strategies including the exertion of compensatory effort. The present study examines the effects of total sleep deprivation on a semantic word priming task. Word priming is unique because it can be carried out using different strategies involving either automatic, effortless or controlled, effortful processing. Twelve subjects were presented with word pairs, a prime and a target, that were either highly semantically associated (cat…dog), weakly associated (cow…barn) or unassociated (apple…road). In order to increase the probability of the use of controlled processing following normal sleep, the subject’s task was to determine if the target word was semantically related to the prime. Furthermore, the time between the offset of the prime and the onset of the target was relatively long, permitting the use of an effortful, expectancy-predictive strategy. Event-related potentials (ERPs) were recorded from 64 electrode sites. After normal sleep, RTs were faster and accuracy higher to highly associated targets; this performance advantage was also maintained following sleep deprivation. A large negative deflection, the N400, was larger to weakly associated and unassociated targets in both sleep-deprived and normal conditions. The overall N400 was however larger in the normal sleep condition. Moreover, a long-lasting negative slow wave developed between the offset of the prime and the onset of the target. These physiological measures are consistent with the use of an effortful, predictive strategy following normal sleep but an automatic, effortless strategy following total sleep deprivation. A picture priming task was also run. This task benefits less from the use of a predictive strategy. Accordingly, in this task, ERPs following the target did not differ as a function of the amount of sleep.