The effects of alcohol intoxication on attention and memory for visual scenes

Effects of alcohol and task difficulty on visual tracking and inattentional blindness

RATIONALE

Inattentional blindness (IB) describes the failure to notice salient but unexpected stimuli in one's focal visual field. It typically occurs while performing a demanding task (e.g. tracking and counting basketball passes), which consumes attentional resources. Alcohol intoxication is also known to reduce attentional resources, thereby potentially increasing IB and disrupting task performance.

OBJECTIVES

To test the extent to which acute alcohol and task difficulty disrupt counting performance and increase the rate of IB across two experimental tasks.

METHODS

To test the effects of alcohol consumption and task difficulty on IB, we used the Simons and Chabris (Percept 28:1059-1074, 1999) and Simons (2010) "gorilla in our midst" basketball clip in experiment 1 and abstract but analogous stimuli presented in a computerised alternative to that task in experiment 2.

RESULTS

IB was associated with increased (counting) task difficulty but not alcohol consumption. However, counting accuracy was impaired by both alcohol and increased task difficulty, with the largest detriment being for alcohol participants who noticed the salient but unexpected stimulus.

CONCLUSION

The absence of alcohol effects on IB in both experiments was unexpected and warrants further investigation in a field vs lab study comparison and in combination with baseline cognitive measures to test for alcohol expectancy and task compensation effects.

The dosing procedure that "makes the poison": Comparing the effects of single versus cumulative alcohol administration methods on emotion recognition

BACKGROUND

Most people often consume alcohol cumulatively and gradually. Yet almost scientific knowledge about alcohol's acute effects on cognition, behavior, and affect stems from laboratory studies that employ a single beverage administration procedure.

OBJECTIVE

This study tests the hypothesis that alcohol's acute effects depend on both methods of administration and alcohol blood level. We introduce a new laboratory procedure for studying cumulative alcohol drinking and examine alcohol's effects on emotion recognition as a function of both alcohol administration method and alcohol blood level.

METHODS

Participants were recruited for one of two studies. One study employed a between-subject design using a single alcoholic dose. Participants were randomly assigned to drink either placebo (0.00%), low (0.03%), moderate (0.06%), or high (0.09%) alcohol levels. The second study employed a within-subject design using a cumulative alcoholic administration method, in which each participant drank four drinks (placebo, followed by three alcoholic drinks). Both groups reached similar breath alcohol concentrations. In both studies, participants attended a single study session, in which emotion recognition was examined following alcohol administration.

RESULTS

Single alcoholic beverage administration method caused greater impairment in emotion recognition ability, specifically for anger, happiness, and fear, as compared with cumulative administration method, even though breath alcohol levels were similar in both conditions.

CONCLUSIONS

This paper presents questions concerning the internal validity of previous laboratory studies that use a single beverage administration procedure. Insights into the effects of alcohol on behavior, as well as regarding our knowledge about models of addiction are presented.

Influence of Alcohol and Cognitive Capacity on Visual Number Judgements

We used an enumeration task to address the question of whether acute alcohol intoxication reduces cognitive or perceptual capacity. To control for individual differences in cognitive resources, we took a sober record of each participant's working memory capacity (WMC). Alcohol was expected to impair enumeration performance, either for the automatic parallel counting of small stimulus sets indicating a perceptual impairment, or the controlled counting or estimating of larger sets indicating a cognitive impairment. Enumeration showed an overall decline in accuracy following a vodka beverage and the deficit was negligible for small sets, which is inconsistent with a loss of perceptual capacity. Having a higher WMC facilitated the enumeration of larger sets and the correlation between WMC and accuracy was stronger in the alcohol condition suggesting that low-WMC participants were more impaired by the beverage. Our findings therefore suggest that alcohol diminished cognitive rather than perceptual capacity.

The intoxicated co-witness: effects of alcohol and dyadic discussion on memory conformity and event recall

RATIONALE

Co-witness discussion is common and often witnesses are under the influence of alcohol. As such, it is important to understand how such factors may influence eyewitness testimony.

OBJECTIVES

We combined a co-witness memory paradigm with an alcohol administration paradigm to examine the influence of alcohol and dyadic discussion on remembering a mock crime.

METHODS

Intoxicated and sober dyads discussed a previously seen video, whilst in a control condition sober and intoxicated individuals recalled the event on their own. Unknown to the dyads, each discussion partner saw a different version of the video including unique details not present in the other video version. All participants then engaged in a second individual recall attempt.

RESULTS

Dyads were more likely to recall misleading details in their individual recall attempts compared to the control group. Intoxicated and sober dyads were equally likely to report misleading information. Alcohol intoxication had no negative impact on individuals' ability to correctly identify the source of their responses. Intoxicated participants recalled fewer details under free recall conditions. Alcohol had a detrimental effect on participants' confidence in their free recall accounts.

CONCLUSIONS

Possible alcohol-related and social-cognitive mechanisms are discussed which may contribute to the current findings as well as applied implications for interviewing intoxicated witnesses.

Eye Tracking Studies Exploring Cognitive and Affective Processes among Alcohol Drinkers: a Systematic Review and Perspectives

Acute alcohol intoxication and alcohol use disorders are characterized by a wide range of psychological and cerebral impairments, which have been widely explored using neuropsychological and neuroscientific techniques. Eye tracking has recently emerged as an innovative tool to renew this exploration, as eye movements offer complementary information on the processes underlying perceptive, attentional, memory or executive abilities. Building on this, the present systematic and critical literature review provides a comprehensive overview of eye tracking studies exploring cognitive and affective processes among alcohol drinkers. Using PRISMA guidelines, 36 papers that measured eye movements among alcohol drinkers were extracted from three databases (PsycINFO, PubMed, Scopus). They were assessed for methodological quality using a standardized procedure, and categorized based on the main cognitive function measured, namely perceptive abilities, attentional bias, executive function, emotion and prevention/intervention. Eye tracking indexes showed that alcohol-related disorders are related to: (1) a stable pattern of basic eye movement impairments, particularly during alcohol intoxication; (2) a robust attentional bias, indexed by increased dwell times for alcohol-related stimuli; (3) a reduced inhibitory control on saccadic movements; (4) an increased pupillary reactivity to visual stimuli, regardless of their emotional content; (5) a limited visual attention to prevention messages. Perspectives for future research are proposed, notably encouraging the exploration of eye movements in severe alcohol use disorders and the establishment of methodological gold standards for eye tracking measures in this field.

Improving intoxicated witness recall with the Enhanced Cognitive Interview

RATIONALE

Witnesses and victims typically provide the central leads in police investigations, yet statistics from past research indicates in many instances these individuals are intoxicated.

OBJECTIVES

To date, however, no research has looked at how best to interview such witnesses to maximise the amount of accurate information they recall.

METHODS

In the present research, whilst on a night out, participants watched a videoed theft whilst either sober or moderately (MBAC = 0.05%) or severely (MBAC = 0.14%) intoxicated. A week later, in a different location, participants were interviewed using either the Enhanced Cognitive (ECI) or Structured Interview.

RESULTS

The ECI was found to improve the recall accuracy and completeness of witness accounts across all three drinking conditions. However, no significant interaction was indicated between alcohol and interview condition.

CONCLUSIONS

The study findings are discussed in terms of their real-world value in aiding police officers to elicit as complete and as accurate an account as possible from intoxicated witnesses.

Gaze entropy measures detect alcohol-induced driver impairment

Driving under the influence of alcohol is an ongoing cause of road traffic accidents. The biphasic nature of alcohol effects on subjective experience appears to contribute to the prevalence of drink-driving, as people perceive the declining phase of the BAC curve as recovery from intoxication and are more willing to drive despite significant impairments in objectively measured functions. The present study investigates whether alcohol-induced changes in gaze behaviour can be detected during engagement in a simulated driving task. In a repeated-measures and placebo-controlled design, this study examines the biphasic influence of moderate alcohol intake (0.6 g/kg) on measures of gaze behaviour and simulated driving performance. Twenty-two healthy young adults completed three driving sessions (baseline, ascending and descending) under two conditions (placebo, alcohol) while their eye movements were simultaneously recorded. The results revealed that gaze behaviour as measured by gaze transition entropy (GTE) and stationary gaze entropy (SGE) and driving performance measured by the standard deviation of lateral position (SDLP) of the vehicle, were significantly affected by alcohol across the ascending and descending sessions. The alcohol-induced reduction in GTE with an increase in SGE is discussed as alcohol's impact on top-down modulation of gaze resulting in more dispersed and erratic pattern of visual scanning. The observed changes in gaze behaviour also mediated the influence of alcohol upon driving performance. These results have significant implications for the development of driver monitoring systems that can detect alcohol-induced impairment.

Observing Alcohol Myopia in the Context of a Trauma Film Paradigm: Differential Recall of Central and Peripheral Details

BACKGROUND

A major tenet of the alcohol myopia model is that intoxication results in a narrowing of attention to the most central environmental cues, at the cost of more peripheral information. Though long hypothesized, no known study of alcohol myopia has demonstrated differential immediate recall of central and peripheral cues using a standardized task. To address this gap, we conducted an alcohol administration study with a clear, standardized focus-a trauma film.

METHODS

Ninety-eight female social drinkers completed self-report measures, and then were randomized to consume a placebo beverage, a low dose of alcohol (mean breath alcohol concentration [BrAC] = 0.04%), or a high dose of alcohol (mean BrAC = 0.11%). Participants then moved to a staged room where they viewed a film clip depicting a sexual assault. After leaving the room, participants completed a written free recall task of the film and the room.

RESULTS

The distinction between recall of central and peripheral details was supported by confirmatory factor analysis. Consistent with the alcohol myopia model, relative to placebo, a high dose of alcohol led to impaired recall of peripheral (but not central) details. Although the interaction between BrAC and information type (central vs. peripheral) was not statistically significant, simple effects revealed a strong association between BrAC and peripheral information, and no association between BrAC and central information. Bolstering myopia as an explanation for our findings, neither central nor peripheral information correlated with self-reported tendencies to dissociate or distract oneself, or typical alcohol consumption or expectancies.

CONCLUSIONS

Alcohol myopia can be observed through an immediate free recall task following a stressful film. Additional research is needed to continue evaluating dose-dependent differential recall in larger samples. This task may be useful for clarifying the role of alcohol myopia in clinical phenomena, such as aggressive behavior and processing traumatic events.

An experimental examination of the effects of alcohol consumption and exposure to misleading postevent information on remembering a hypothetical rape scenario

We experimentally examined the effects of alcohol consumption and exposure to misleading postevent information on memory for a hypothetical interactive rape scenario. We used a 2 beverage (alcohol vs. tonic water) × 2 expectancy (told alcohol vs. told tonic) factorial design. Participants (N = 80) were randomly assigned to conditions. They consumed alcohol (mean blood alcohol content = 0.06%) or tonic water before engaging in the scenario. Alcohol expectancy was controlled by telling participants they were consuming alcohol or tonic water alone, irrespective of the actual beverage they were consuming. Approximately a week later, participants were exposed to a misleading postevent narrative and then recalled the scenario and took a recognition test. Participants who were told that they had consumed alcohol rather than tonic reported fewer correct details, but they were no more likely to report incorrect or misleading information. The confidence-accuracy relationship for control and misled items was similar across groups, and there was some evidence that metacognitive discrimination was better for participants who were told that they had consumed alcohol compared with those told they had tonic water. Implications for interviewing rape victims are discussed.

Alcohol increases inattentional blindness when cognitive resources are not consumed by ongoing task demands

RATIONALE

Inattentional blindness (IB) is the inability to detect a salient yet unexpected task irrelevant stimulus in one's visual field when attention is engaged in an ongoing primary task. The present study is the first to examine the impact of both task difficulty and alcohol consumption on IB and primary task performance.

OBJECTIVES

On the basis of alcohol myopia theory, the combined effects of increased task difficulty and alcohol intoxication were predicted to impair task performance and restrict the focus of attention on to task-relevant stimuli. We therefore expected increases in breath alcohol concentration to be associated with poorer primary task performance and higher rates of IB, with these relationships being stronger under hard than easy task conditions.

METHODS

This hypothesis was tested in a field study where alcohol drinkers in a local bar were randomly assigned to perform a dynamic IB task with an easy or hard visual tracking and counting task at its core (Simons and Chabris in Perception 28:1059-1074, 1999).

RESULTS

Increasing the difficulty of the primary task reduced task accuracy but, surprisingly, had no impact on the rate of IB. Higher levels of alcohol intoxication were, however, associated with poorer task performance and an increased rate of IB, but only under easy primary task conditions.

CONCLUSIONS

Results are consistent with alcohol myopia theory. Alcohol intoxication depletes attentional resources, thus reducing the drinker's awareness of salient stimuli that are irrelevant to some ongoing primary task. We conclude that this effect was not observed for our hard task because it is more resource intensive, so leaves no spare attentional capacity for alcohol to deplete.

Do intoxicated witnesses produce poor facial composite images?

RATIONALE

The effect of alcohol intoxication on witness memory and performance has been the subject of research for some time, however, whether intoxication affects facial composite construction has not been investigated.

OBJECTIVES

Intoxication was predicted to adversely affect facial composite construction.

METHODS

Thirty-two participants were allocated to one of four beverage conditions consisting of factorial combinations of alcohol or placebo at face encoding, and later construction. Participants viewed a video of a target person and constructed a composite of this target the following day. The resulting images were presented as a full face composite, or a part face consisting of either internal or external facial features to a second sample of participants who provided likeness ratings as a measure of facial composite quality.

RESULTS

Intoxication at face encoding had a detrimental impact on the quality of facial composites produced the following day, suggesting that alcohol impaired the encoding of the target faces. The common finding that external compared to internal features are more accurately represented was demonstrated, even following alcohol at encoding. This finding was moderated by alcohol and target face gender such that alcohol at face encoding resulted in reduced likeness of external features for male composite faces only.

CONCLUSIONS

Moderate alcohol intoxication impairs the quality of facial composites, adding to existing literature demonstrating little effect of alcohol on line-up studies. The impact of intoxication on face perception mechanisms, and the apparent narrowing of processing to external face areas such as hair, is discussed in the context of alcohol myopia theory.

Interviewing intoxicated witnesses: Memory performance in theory and practice

Memory encoding and recall involving complex, effortful cognitive processes are impaired by alcohol primarily due to impairment of a select few, but crucial, cortical areas. This review shows how alcohol affects some, but not all, aspects of eyewitnesses' oral free recall performance. The principal results, so far, are that: a) free recall reports by intoxicated witnesses (at the investigated BAC-levels) may contain less, but as accurate, information as reports by sober witnesses; b) immediate reports given by intoxicated witnesses may yield more information compared to reports by sober witnesses given after a one week delay; c) an immediate interview may enhance both intoxicated and sober witnesses' ability to report information in a later interview; and d) reminiscence seems to occur over repeated interviews and the new information seems to be as accurate as the previously reported information. Based on this, recommendations are given for future research to enhance understanding of the multifaceted impact of alcohol on witnesses' oral free recall of violent crimes.

The Effects of Alcohol Intoxication on Accuracy and the Confidence-Accuracy Relationship in Photographic Simultaneous Line-ups

Acute alcohol intoxication during encoding can impair subsequent identification accuracy, but results across studies have been inconsistent, with studies often finding no effect. Little is also known about how alcohol intoxication affects the identification confidence-accuracy relationship. We randomly assigned women (N = 153) to consume alcohol (dosed to achieve a 0.08% blood alcohol content) or tonic water, controlling for alcohol expectancy. Women then participated in an interactive hypothetical sexual assault scenario and, 24 hours or 7 days later, attempted to identify the assailant from a perpetrator present or a perpetrator absent simultaneous line-up and reported their decision confidence. Overall, levels of identification accuracy were similar across the alcohol and tonic water groups. However, women who had consumed tonic water as opposed to alcohol identified the assailant with higher confidence on average. Further, calibration analyses suggested that confidence is predictive of accuracy regardless of alcohol consumption. The theoretical and applied implications of our results are discussed.

Alcohol-induced retrograde facilitation renders witnesses of crime less suggestible to misinformation

RATIONALE

Research has shown that alcohol can have both detrimental and facilitating effects on memory: intoxication can lead to poor memory for information encoded after alcohol consumption (anterograde amnesia) and may improve memory for information encoded before consumption (retrograde facilitation). This study examined whether alcohol consumed after witnessing a crime can render individuals less vulnerable to misleading post-event information (misinformation).

METHOD

Participants watched a simulated crime video. Thereafter, one third of participants expected and received alcohol (alcohol group), one third did not expect but received alcohol (reverse placebo), and one third did not expect nor receive alcohol (control). After alcohol consumption, participants were exposed to misinformation embedded in a written narrative about the crime. The following day, participants completed a cued-recall questionnaire about the event.

RESULTS

Control participants were more likely to report misinformation compared to the alcohol and reverse placebo group.

CONCLUSION

The findings suggest that we may oversimplify the effect alcohol has on suggestibility and that sometimes alcohol can have beneficial effects on eyewitness memory by protecting against misleading post-event information.

Testing Alcohol Myopia Theory: Examining the Effects of Alcohol Intoxication on Simultaneous Central and Peripheral Attention

The effect of alcohol intoxication on central and peripheral attention was examined as a test of Alcohol Myopia Theory (AMT). Previous research has supported AMT in the context of visual attention, but few studies have examined the effects of alcohol intoxication on central and peripheral attention. The study followed a 2 (alcohol treatment) × 2 (array size) × 2 (task type) mixed design. Forty-one participants (placebo or intoxicated) viewed an array of four or six colored circles, while simultaneously counting the flashes of a centrally presented fixation cross. Participants were instructed to prioritize flash counting accuracy. The subsequently presented colored probe matched the cued peripheral stimulus on 50% of trials. Flash counting and probe identification accuracy were recorded. There was a significant main effect of alcohol treatment on accuracy scores, as well as an alcohol treatment by task type interaction. Accuracy scores for the central flash counting task did not differ between treatment groups, but scores for peripheral probe identification were lower in the alcohol group. As predicted by AMT, alcohol impairment was greater for peripheral probe detection than for the central and prioritized flash counting task. The findings support the notion that alcohol intoxication narrows attentional focus to the central aspects of a task.

When alcohol narrows the field of focal attention

The aim of this study was to measure the extent to which alcohol intoxication restricts the scope of attention in the visual field. A group of intoxicated ( n = 31; mean BAC ≈ .08%) and placebo control ( n = 31; mean BAC ≈ .00%) participants were required to correctly identify visual probes while performing two verbal categorization tasks: one designed to widen the scope of visual attention on to each stimulus word, the other to narrow attention on to the central letter of each word. Response times to surprise probes interpolated between categorization trials were measured and these catch trials could appear in any of the stimulus word letter positions. As predicted by alcohol myopia theory (AMT), which assumes that the drug narrows focal attention, intoxicated participants made slower responses than the sober controls to probes displayed in non-central letter positions, although right-field probe reaction times (RTs) were slower than those for left-field targets. This response asymmetry and the wider theoretical implications of these findings are discussed.

The effects of acute alcohol intoxication on the cognitive mechanisms underlying false facial recognition

RATIONALE

False face recognition rates are sometimes higher when faces are learned while under the influence of alcohol. Alcohol myopia theory (AMT) proposes that acute alcohol intoxication during face learning causes people to attend to only the most salient features of a face, impairing the encoding of less salient facial features. Yet, there is currently no direct evidence to support this claim.

OBJECTIVES

Our objective was to test whether acute alcohol intoxication impairs face learning by causing subjects to attend to a salient (i.e., distinctive) facial feature over other facial features, as per AMT.

METHODS

We employed a balanced placebo design (N = 100). Subjects in the alcohol group were dosed to achieve a blood alcohol concentration (BAC) of 0.06 %, whereas the no alcohol group consumed tonic water. Alcohol expectancy was controlled. Subjects studied faces with or without a distinctive feature (e.g., scar, piercing). An old-new recognition test followed. Some of the test faces were "old" (i.e., previously studied), and some were "new" (i.e., not previously studied). We varied whether the new test faces had a previously studied distinctive feature versus other familiar characteristics.

RESULTS

Intoxicated and sober recognition accuracy was comparable, but subjects in the alcohol group made more positive identifications overall compared to the no alcohol group.

CONCLUSIONS

The results are not in keeping with AMT. Rather, a more general cognitive mechanism appears to underlie false face recognition in intoxicated subjects. Specifically, acute alcohol intoxication during face learning results in more liberal choosing, perhaps because of an increased reliance on familiarity.

Some effects of alcohol and eye movements on cross-race face learning

This study examines the impact of acute alcohol intoxication on visual scanning in cross-race face learning. The eye movements of a group of white British participants were recorded as they encoded a series of own-and different-race faces, under alcohol and placebo conditions. Intoxication reduced the rate and extent of visual scanning during face encoding, reorienting the focus of foveal attention away from the eyes and towards the nose. Differences in encoding eye movements also varied between own-and different-race face conditions as a function of alcohol. Fixations to both face types were less frequent and more lingering following intoxication, but in the placebo condition this was only the case for different-race faces. While reducing visual scanning, however, alcohol had no adverse effect on memory, only encoding restrictions associated with sober different-race face processing led to poorer recognition. These results support perceptual expertise accounts of own-race face processing, but suggest the adverse effects of alcohol on face learning published previously are not caused by foveal encoding restrictions. The implications of these findings for alcohol myopia theory are discussed.