Impaired face symmetry detection under alcohol, but no 'beer goggles' effect.

BACKGROUND: The 'beer goggles' phenomenon describes sexual attraction to individuals when alcohol intoxicated whom we would not desire when sober. One possible explanation of the effect is that alcohol impairs the detection of facial asymmetry, thus lowering the drinker's threshold for physical attraction. AIMS: We therefore tested the hypotheses that higher breath alcohol drinkers would award more generous ratings of attractiveness to asymmetrical faces, and be poorer at discriminating bilateral facial asymmetry than less intoxicated counterparts. METHODS: Ninety-nine male and female bar patrons rated 18 individual faces for attractiveness and symmetry. Each type of rating was given twice, once per face with an enhanced asymmetry and once again for each face in its natural form. Participants then judged which of two same-face versions (one normal, the other perfectly symmetrised) was more attractive and, in the final task, more symmetrical. RESULTS: Alcohol had no influence on attractiveness judgements but higher blood alcohol concentrations were associated with higher symmetry ratings. Furthermore, as predicted, heavily intoxicated individuals were less able to distinguish natural from perfectly symmetrised face versions than more sober drinkers. CONCLUSIONS: Findings therefore suggest alcohol impairs face asymmetry detection, but it seems that this perceptual distortion does not contribute to the 'beer goggles' phenomenon.

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.

Acute alcohol intoxication and the cocktail party problem: do "mocktails" help or hinder?

RATIONALE: To test the notion that alcohol impairs auditory attentional control by reducing the listener's cognitive capacity. OBJECTIVES: We examined the effect of alcohol consumption and working memory span on dichotic speech shadowing and the cocktail party effect-the ability to focus on one of many simultaneous speakers yet still detect mention of one's name amidst the background speech. Alcohol was expected either to increase name detection, by weakening the inhibition of irrelevant speech, or reduce name detection, by restricting auditory attention on to the primary input channel. Low-span participants were expected to show larger drug impairments than high-span counterparts. METHODS: On completion of the working memory span task, participants (n = 81) were randomly assigned to an alcohol or placebo beverage treatment. After alcohol absorption, they shadowed speech presented to one ear while ignoring the synchronised speech of a different speaker presented to the other. Each participant's first name was covertly embedded in to-be-ignored speech. RESULTS: The "cocktail party effect" was not affected by alcohol or working memory span, though low-span participants made more shadowing errors and recalled fewer words from the primary channel than high-span counterparts. Bayes factors support a null effect of alcohol on the cocktail party phenomenon, on shadowing errors and on memory for either shadowed or ignored speech. CONCLUSION: Findings suggest that an alcoholic beverage producing a moderate level of intoxication (M BAC ≈ 0.08%) neither enhances nor impairs the cocktail party effect.

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.

Alcohol myopia and the distracting effects of hair in face recognition.

BACKGROUND: According to alcohol myopia theory, alcohol reduces cognitive resources and restricts the drinker's attention to only the more prominent aspects of a visual scene. As human hairstyles are often salient and serve as important facial recognition cues, we consider whether alcohol restricts attention to this region of faces upon initial viewing. AIMS: Participants with higher breath alcohol concentrations just prior to encoding a series of unfamiliar faces were expected to be poorer than more sober counterparts at recognising the internal but not external features of those faces at test. METHODS: Drinkers in a nearby bar (n=76) were breathalysed and then shown a sequence of 21 full face photos. After a filled five-minute retention interval they completed a facial recognition task requiring them to identify the full, internal or external region of each of these among a sequence of 21 previously unseen (part or whole) faces. RESULTS: As predicted, higher breath concentrations were associated with poorer discrimination of internal but not external face regions. CONCLUSIONS: Our findings suggest that alcohol restricts unfamiliar face encoding by narrowing the scope of attention to the exterior region of unfamiliar faces. This has important implications for drunk eyewitness accuracy, though further investigation is needed to see if the effect is mediated by gender, hair length and face feature distinctiveness.

Alcohol and disgust: An intimate relationship.

BACKGROUND: Alcohol intoxication has been associated with increases in risk taking behavior and more ambiguously, alterations in emotional perception. In the first study of its kind, we examine how theories of disgust can be used to help explain these effects. METHODS: Using a single-blind procedure, participants (n = 73) were randomly allocated to an alcohol (Males: 0.68 g/kg; Females: 0.60 g/kg) or placebo condition and then completed a psychometric measure of disgust (TDDS). RESULTS: Results revealed a non-significant trend toward lower disgust sensitivity in the alcohol versus placebo condition. We did however find a significant negative correlation, whereby increases in breath alcohol level were associated with decreased pathogen disgust. CONCLUSIONS: These findings demonstrate a relationship between breath alcohol level and disgust sensitivity which could help explain differences in risk associated behavior.

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.

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.

Lineup identification accuracy: the effects of alcohol, target presence, confidence ratings, and response time / La precisión de la identificación en las ruedas de reconocimiento: efectos del alcohol, la presencia del objetivo, la valoración de la confianza y el tiempo de respuesta

Despite the intoxication of many eyewitnesses at crime scenes, only four published studies to date have investigated the effects of alcohol intoxication on eyewitness identification performance. While one found intoxication significantly increased false identification rates from target absent showups, three found no such effect using the more traditional lineup procedure. The present study sought to further explore the effects of alcohol intoxication on identification performance and examine whether accurate decisions from intoxicated witnesses could be postdicted by confidence and response times. One hundred and twenty participants engaged in a study examining the effects of intoxication (control, placebo, and mild intoxication) and target presence on identification performance. Participants viewed a simultaneous lineup one week after watching a mock crime video of a man attempting to steal cars. Ethanol intoxication (0.6 ml/kg) was found to make no significant difference to identification accuracy and such identifications from intoxicated individuals were made no less confidently or slowly than those from sober witnesses. These results are discussed with respect to the previous research examining intoxicated witness identification accuracy and the misconceptions the criminal justice system holds about the accuracy of such witnesses (AU)

A pesar de la existencia de intoxicación etílica en muchos testigos oculares de escenas de crimen, hasta la fecha solo hay cuatro estudios publicados que investigan sus efectos en la intervención de los testigos oculares durante la identificación. Solo uno de ellos halló que la intoxicación aumentaba de modo significativo la proporción de identificaciones falsas a partir de presentaciones en ausencia del objetivo y los otros tres no hallaron dicho efecto utilizando el clásico procedimiento de ruedas de reconocimiento. Este estudio ha intentado ampliar la exploración de los efectos de la intoxicación etílica en la actuación en identificaciones y analizar si se podrían conjeturar decisiones precisas por parte de testigos presenciales intoxicados a partir de la confianza y de los tiempos de respuesta. En el estudio para analizar los efectos de la intoxicación participaron 120 personas (control, placebo e intoxicación leve), con presencia del objetivo en la tarea de identificación. Los participantes vieron una rueda de reconocimiento simultánea una semana después, presenciando un video que simulaba un delito cometido por un hombre que intentaba robar coches. Se encontró que la intoxicación etílica (0.6 ml/kg) no suponía diferencia significativa alguna en la precisión de la identificación, además de que tales identificaciones de personas intoxicadas no se llevaban a cabo de un modo menos fiable o lento que las de testigos sobrios. Se comentan los resultados en relación a investigaciones previas, analizando la precisión de la identificación de testigos intoxicados y las falsas creencias que el sistema de justicia penal mantiene acerca de la precisión de tales testigos (AU)

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.

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.

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

This study tests the claim that alcohol intoxication narrows the focus of visual attention on to the more salient features of a visual scene. A group of alcohol intoxicated and sober participants had their eye movements recorded as they encoded a photographic image featuring a central event of either high or low salience. All participants then recalled the details of the image the following day when sober. We sought to determine whether the alcohol group would pay less attention to the peripheral features of the encoded scene than their sober counterparts, whether this effect of attentional narrowing was stronger for the high-salience event than for the low-salience event, and whether it would lead to a corresponding deficit in peripheral recall. Alcohol was found to narrow the focus of foveal attention to the central features of both images but did not facilitate recall from this region. It also reduced the overall amount of information accurately recalled from each scene. These findings demonstrate that the concept of alcohol myopia originally posited to explain the social consequences of intoxication (Steele & Josephs, 1990) may be extended to explain the relative neglect of peripheral information during the processing of visual scenes.

Scale-invariant and locally distinctive memory: the SIMPLE approach.

A long-standing controversy in cognitive psychology concerns the need to assume short- and long-term memory stores. A new formal model of scale-invariant memory and perceptual identification, SIMPLE, accounts for a wide range of data over short and long time scales using the same basic retrieval principles. SIMPLE assumes a single store in which the distinctiveness of each memory item is calculated relative to other items presented across the same scale.

Input and output modality effects in immediate serial recall.

In immediate recall tasks, visual recency is substantially enhanced when output interference is low (Cowan, Saults, Elliott, & Moreno, 2002; Craik, 1969) whereas auditory recency remains high even under conditions of high output interference. This auditory advantage has been interpreted in terms of auditory resistance to output interference (e.g., Neath & Surprenant, 2003). In this study the auditory-visual difference at low output interference re-emerged when ceiling effects were accounted for, but only with spoken output. With written responding the auditory advantage remained significantly larger with high than with low output interference. These new data suggest that both superior auditory encoding and modality-specific output interference contribute to the classic auditory-visual modality effect.