Sarah J. Bayless

Recognising upright and inverted faces: MEG source localisation

Face recognition is a complex cognitive task that involves a distributed network of neural sources. While some components of this network have been identified, the temporal sequence of these components is not well understood. Magnetoencephalography (MEG), analyzed with a spatial filtering source localisation algorithm, was used to determine frontal contributions to face recognition. We tested 22 adults (mean age 26.3 years; 10 females). Upright and inverted faces were presented in counter-balanced blocks and subjects identified repetitions in a 1-back protocol. MEG data were recorded continuously from a 151 channel CTF machine and source localised to each participants MRI. The classic face components, M100 and M170, were seen for upright and inverted faces with M100 localizing to bilateral occipital areas and M170 to bilateral fusiform areas. A third component, M240, showed high global field power to correctly recognised repeated faces and localised to right middle frontal and insula sources at 240 ms for upright faces and bilateral mid-frontal sources for inverted faces. The effect of repetition was examined and a source identified at 250 ms in the cingulate, for inverted faces. These results provide timing information on frontal lobe activation, seen reliably in fMRI memory studies; the immediate recognition of repeated faces activates the right frontal sources at 240-250 ms, with bilateral activation to repeated inverted faces, perhaps due to increased task difficulty.

Is it in the eyes? Dissociating the role of emotion and perceptual features of emotionally expressive faces in modulating orienting to eye gaze

This study investigated the role of the eye region of emotional facial expressions in modulating gaze orienting effects. Eye widening is characteristic of fearful and surprised expressions and may significantly increase the salience of perceived gaze direction. This perceptual bias rather than the emotional valence of certain expressions may drive enhanced gaze orienting effects. In a series of three experiments involving low anxiety participants, different emotional expressions were tested using a gaze-cueing paradigm. Fearful and surprised expressions enhanced the gaze orienting effect compared with happy or angry expressions. Presenting only the eye regions as cueing stimuli eliminated this effect whereas inversion globally reduced it. Both inversion and the use of eyes only attenuated the emotional valence of stimuli without affecting the perceptual salience of the eyes. The findings thus suggest that low-level stimulus features alone are not sufficient to drive gaze orienting modulations by emotion. Rather, they interact with the emotional valence of the expression that appears critical. The study supports the view that rapid processing of fearful and surprised emotional expressions can potentiate orienting to another persons averted gaze in non-anxious people.

Behaviour difficulties and cognitive function in children born very prematurely

Children born very prematurely are at risk of low average IQ and behaviour difficulties throughout childhood and adolescence. Associations among preterm birth, IQ and behaviour have been reported; however, the nature of the relationship among these outcomes is not fully understood. Some studies have proposed that the consequences of preterm birth, such as low average IQ, mediate the association between preterm birth and later behaviour difficulties. The aim of this study was to investigate the relationship among preterm birth, IQ and childhood behaviour problems, by testing mediation and moderation models. We assessed a UK sample of 69 very preterm (< 32 weeks gestational age) and 70 term born children aged between 6 and 12 years on an abbreviated IQ test. Parental behaviour ratings were obtained using the Strengths and Difficulties Questionnaire. Mediation and moderation models were tested using hierarchical regression analyses. The findings indicate that IQ mediates the relationship between birth status and emotional behaviour problems. Furthermore, the results indicate that birth status moderates the relationship between IQ and behavioural difficulties, i.e., that the relationship between low IQ and behaviour problems is most pronounced for the preterm children. The findings highlight the importance of considering indirect effects in the study of outcome after very preterm birth.

Spatiotemporal analysis of feedback processing during a card sorting task using spatially filtered MEG

A card sorting paradigm was used to observe the neural correlates of feedback processing in adult participants. Visually presented feedback was used to indicate response accuracy and the requirement to shift response set in a 2-category card sorting task. Magnetoencephalography (MEG) responses to feedback cues were analysed using a beamformer-based spatial filtering algorithm (event-related Synthetic Aperture Magnetometry, erSAM). Analysis of source power revealed activity in rostral anterior cingulate cortex (ACC) only to negative feedback processing, which peaked at 260 ms after stimulus onset. The results are in agreement with both evidence from fMRI on spatial characteristics of negative feedback processing, and evidence from event-related potentials (ERPs) on the temporal profile of this ACC response. The superior temporal gyrus was activated only with positive feedback, reflecting integration of actions with successful outcomes. The present MEG erSAM findings are the first to provide both accurate spatial localization as well as temporal specificity for the neural correlates of feedback processing.

Spatio-temporal localisation of attentional orienting to gaze and peripheral cues.

Another persons eye gaze often triggers our attention such that we follow their direction of gaze. We investigated how the neural mechanisms for processing eye-gaze and spatial attention interact using magnetoencephalography (MEG) in young adults. In a cueing paradigm, a face was presented centrally with left or right averted eye-gaze serving as the directional cue in the eye-gaze condition. In the peripheral cue condition, the face with a straight gaze was presented with a cue stimulus appearing on the left or right of the face. Cue validity was 50%. MEG was recorded during the two conditions and event-related beamforming was used to determine the timing and location of the brain activity related to the two types of cueing. The MEG data indicated that generally the network of activation in response to our two cue types was similar. In contrast, MEG responses to the targets demonstrated one main peak at 286-306 ms for the eye-gaze cue condition while two peaks were found at 238-258 ms and 286-306 ms for the peripheral cue condition. Activation was also consistently larger for the invalid than valid trials. Source images for the invalid minus valid contrasts for the 238-258 ms window showed significant activation only in the peripheral cueing condition, in the left temporoparietal junction and left inferior frontal gyrus. In the 286-306 ms window, both conditions showed left medial frontal activations. Thus, peripheral cues showed more rapid neural processing than the eye-gaze cues, with the second component being common to both, reflecting in part common processing. We suggest that attentional processing was maximal in the left hemisphere, as the right hemisphere was likely engaged in processing the face 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.

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

RationaleInattentional 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.ObjectivesOn 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.MethodsThis 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).ResultsIncreasing 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.ConclusionsResults 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

RationaleThe 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.ObjectivesIntoxication was predicted to adversely affect facial composite construction.MethodsThirty-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.ResultsIntoxication 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.ConclusionsModerate 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.