Electrophysiological correlates of the composite face illusion: Disentangling perceptual and decisional components of holistic face processing in the human brain

When the bottom halves of two faces differ, people’s behavioral judgment of the identical top halves of those faces is impaired: they report that the top halves are different, and/or take more time than usual to provide a response. This behavioral measure is known as the composite face effect (CFE) and has traditionally been taken as evidence that faces are perceived holistically. Recently, however, it has been claimed that this effect is driven almost entirely by decisional, rather than perceptual, factors ( Richler, Gauthier, Wenger, & Palmeri, 2008). To disentangle the contribution of perceptual and decisional brain processes, we aimed to obtain an event-related potential (ERP) measure of the CFE at a stage of face encoding ( Jacques & Rossion, 2009) in the absence of a behavioral CFE effect. Sixteen participants performed a go/no-go task in an oddball paradigm, lifting a finger of their right or left hand when the top half of a face changed identity. This change of identity of the top of the face was associated with an increased ERP signal on occipito-temporal electrode sites at the N170 face-sensitive component (∼160 ms), the later decisional P3b component, and the lateralized readiness potential (LRP) starting at ∼350 ms. The N170 effect was observed equally early when only the unattended bottom part of the face changed, indicating that an identity change was perceived across the whole face in this condition. Importantly, there was no behavioral response bias for the bottom change trials, and no evidence of decisional biases from electrophysiological data (no P3b and LRP deflection in no-go trials). These data show that an early CFE can be measured in ERPs in the absence of any decisional response bias, indicating that the CFE reflects primarily the visual perception of the whole face.     

Deconstructing the tower: Parameters and predictors of problem difficulty on the Tower of London task

The Tower of London (TOL) task has been widely used in both clinical and research realms. In the current study, 104 healthy participants attempted all possible moderate- to high-difficulty TOL problems in order to determine: (1) optimal measures of problem solving performance, (2) problem characteristics, other than the minimum moves necessary to solve the problem, that determine participants’ difficulty in solving problems successfully, quickly, and efficiently, and (3) effects of increased task experience on which problem characteristics determine problem difficulty. A factor analysis of six performance measures found that, regardless of task experience, problem difficulty could be captured well either by a single factor corresponding to general quality of solution or possibly by three subordinate factors corresponding to solution efficiency, solution speed, and initial planning speed. Regression analyses predicting these performance factors revealed that in addition to a problem’s minimum moves three problem parameters were critical in determining the problem difficulty: goal position hierarchy, start position hierarchy, and number of solution paths available. The relative contributions of each of the characteristics strongly depended on which performance factor defined performance. We conclude that TOL problem performance is multifaceted, and that classifying problem difficulty using only the minimum moves necessary to solve the problem is inadequate.     

The influence of heightened body‐awareness on walking through apertures

The reported study measured the ratio between aperture‐width and hip‐width that marked the critical transition from frontal walking to body rotation for male and female participants. Half of the participants of each sex wore form‐fitting lycra clothes and half loose‐fitting jogging suits. Participants wearing the form‐fitting clothing reported heightened body awareness relative to those wearing the loose‐fitting clothing. For male participants this difference was reflected in a smaller aperture‐to‐hip ratio in the form‐fitting than loose‐fitting clothing condition. That is, males walked frontally through smaller apertures when wearing form‐fitting than when wearing loose‐fitting clothing. For females there was no difference in walking action as a function of clothing style. Results are discussed in terms of the perception of action opportunities in the environment, the influence of body awareness on such perception and sex differences. Copyright © 2009 John Wiley & Sons, Ltd.     

Effects of anesthetic agents on socially transmitted olfactory memories in mice

Mice can learn a food preference from odor cues transmitted on the breath of a conspecific, even if the “demonstrator” is anesthetized. To our knowledge there are no studies examining the effect of anesthetizing the “observer” on development of memory for socially transmitted food preferences (STFP). In Experiment 1 we found that 2–4 month-old F2 C57Bl/6x129sv male and female mice demonstrated a STFP after a 5 min exposure to an anesthetized demonstrator mouse when tested 24 h later. In Experiment 2, observer mice anesthetized with Sagatal (60 mg/kg) prior to the “social interaction” preferentially avoided the cued food when tested 24 h later. This aversion was not due to any overt aversive effects of this dose of Sagatal because mice that ate the food and were then anesthetized, or could only smell the food for 5 min while anesthetized, showed no preference or aversion. In a third experiment we found that the Sagatal-induced aversion was not a general property of anesthesia because there were varied results produced by observer mice treated with anesthetic drugs with different mechanisms of action. Vetalar (200 mg/kg) and Rompun (10 mg/kg) treated animals ate similar amounts of cued and non-cued food at test, indicating an absence of learning. Hypnorm (0.5 ml/kg) treated animals showed a preference for the cued food whereas those treated with Hypnovel (2.5 ml/kg) showed an aversion to the cued food. These results show that the food aversion observed with Sagatal is not a general property of anesthetic agents, but appears to be restricted to those acting primarily on the GABAergic system. Thus, we have shown that under certain conditions it is possible for an anesthetized observer mouse to learn a preference or aversion of a socially-linked olfactory cue.     

The Role of Occupational Characteristics and Occupational Imbalance in Explaining Well-being

One of the key factors for promoting well-being lies in balancing one’s daily life occupations and the nature of these occupations. Occupation refers to a group of everyday life goal-directed activities which may be associated to any life domain, not necessarily work, such as leisure, education, or self-care. Yet it is not clear what constitutes occupational imbalance, and its association to other factors has not been examined systematically. This study proposed and tested a theoretical model for specifying the structural relationships between occupational imbalance, occupational characteristics, personality and well-being. 288 working adults completed the following questionnaires: Inter-goal Relations Questionnaire (occupational imbalance), Personal Projects Analysis (occupational characteristics), the Big Five Inventory (personality traits) and the Satisfaction with Life Scale (well-being). Twenty-five models were tested using structural equation modeling. All the models fit the data well. Occupational characteristics, with the exception of stress, served as significant mediators between personality and well-being, yet occupational imbalance did not play a significant role across all models. Our findings provide substantial support for the importance of occupation to well-being, however occupational imbalance is still an elusive concept that requires further investigation theoretically and empirically.     

From Theory to Intervention: Mapping Theoretically Derived Behavioural Determinants to Behaviour Change Techniques

Theory provides a helpful basis for designing interventions to change behaviour but offers little guidance on how to do this. This paper aims to illustrate methods for developing an extensive list of behaviour change techniques (with definitions) and for linking techniques to theoretical constructs. A list of techniques and definitions was generated from techniques published in two systematic reviews, supplemented by "brainstorming" and a systematic search of nine textbooks used in training applied psychologists. Inter-rater reliability of extracting the techniques and definitions from the textbooks was assessed. Four experts judged which techniques would be effective in changing 11 theoretical constructs associated with behaviour change. Thirty-five techniques identified in the reviews were extended to 53 by brainstorming and to 137 by consulting textbooks. Agreement for the 53 definitions was 74.7 per cent (15.4% cells completed and 59.3% cells empty for both raters). Agreement about the link between the 35 techniques and theoretical constructs was 71.7 per cent of 385 judgments (12.2% agreement that effective and 59.5% agreement that not effective). This preliminary work demonstrates the possibility of developing a comprehensive, reliable taxonomy of techniques linked to theory. Further refinement is needed to eliminate redundancies, resolve uncertainties, and complete technique definitions.     

Neurophysiology and neuroanatomy of reflexive and voluntary saccades in non-human primates

A multitude of cognitive functions can easily be tested by a number of relatively simple saccadic eye movement tasks. This approach has been employed extensively with patient populations to investigate the functional deficits associated with psychiatric disorders. Neurophysiological studies in non-human primates performing the same tasks have begun to provide us with insights into the neural mechanisms underlying many cognitive functions. Here, we review studies that have investigated single neuron activity in the superior colliculus (see glossary), frontal eye field, supplementary eye field, dorsolateral prefrontal cortex, anterior cingulate (see glossary) cortex and lateral intraparietal area associated with the performance of visually guided saccades, anti-saccades and memory-guided saccades in awake behaving monkeys.     

Substance Use and Health and Safety among Homeless Youth

This study examines how substance use is associated with the health and safety of homeless youth using cross-sectional, self-report data from 285 homeless adolescents. Path models were used to examine concurrent relationships between youth’s substance use and multiple aspects of their health and safety, including measures of psychological distress, housing risk and instability, and medical problems. Substance use was examined with both global (i.e., a composite of days of use across various drugs and alcohol) and specific (i.e., rates of use of specific drugs, injection drug use) measures. After controlling for demographic and historical variables, number of days of use was significantly related to psychological distress, whereas injection drug use was significantly related to housing risk. Examination of specific drugs revealed relationships between psychological distress and the use of alcohol, cocaine, and amphetamines, and a specific relationship between housing risk and the use of heroin. None of the measures of substance use was significantly related to youth’s medical problems. Implications for interventions with homeless adolescents are discussed.