Event-related potentials indicate different processes to mediate categorical and associative priming in person recognition

Whether representations of people are stored in associative networks based on co-occurrence or are stored in terms of more abstract semantic categories is a controversial question. In the present study, participants performed fame decisions to unfamiliar or famous target faces (Experiment 1) or names (Experiment 2), which were primed, either by highly associated celebrity names or by names from the same occupational category, or were unprimed. Reaction times and event-related potentials (ERPs) were recorded. Reaction times yielded significant priming effects for both associated and same category conditions. ERPs to targets in the associated condition were significantly more positive than were ERPs in all other conditions over central and parietal areas (300-600 ms; N400 priming effect). By contrast, a more posterior effect was found for categorical priming. These findings held for both cross-domain (Experiment 1) and within-domain conditions (Experiment 2). Results (a) demonstrate behavioral and ERP evidence for categorical priming in person recognition, consistent with the assumption that shared semantic information units can mediate semantic priming, and (b) suggest that associative and categorical priming are based on mechanisms that are at least partially different.     

On the interplay between familiarity and emotional expression in face perception

Traditional models of face perception (e.g. Bruce and Young 1986) stress independent routes for processing identity and emotional expression. We investigated the interplay between familiarity and emotional expression by systematically varying both factors. In contrast to earlier studies which used binary forced-choice decisions, participants had to judge the familiarity of the presented face and the emotional hedonic valence and emotional arousal of its expressed emotion (angry, happy or neutral), using rating scales. The results demonstrated symmetric, strong interactions between familiarity and expressed emotion. Thus, this study supports more recent models of face perception (Haxby et al. 2000) that were mostly based on brain imaging data. These data together with our behavioural results emphasize the interaction of emotional expression and personal identity and support approaches that propose a relative segregation of these processes, rather than completely independent coding (Calder and Young 2005).     

The Swedish National Adult Reading Test (NART-SWE): a test of premorbid IQ

The purpose of this study was to construct a Swedish version of the National Adult Reading Test (NART-SWE), a test for assessment of premorbid IQ, and to investigate its validity and reliability on healthy controls and patients with mild Alzheimer's disease. As Swedish pronunciation rules are fixed, NART-SWE was constructed using loan words. NART-SWE has satisfactory psychometric properties: Inter-rater and retest reliability as well as internal consistency are very high. The NART-SWE demonstrates face validity. In addition, high correlation with IQ was obtained. A significant model emerged when using NART-SWE to predict IQ. Furthermore, no significant differences were observed when comparing performance for healthy controls' with that of patients with Alzheimer's disease on NART-SWE. It does appear that reading of irregular words is intact in mild Alzheimer's disease.     

Negative self-focused cognitions mediate the effect of trait social anxiety on state anxiety

The cognitive model of social anxiety predicts that negative self-focused cognitions increase anxiety when anticipating social threat. To test this prediction, 36 individuals were asked to anticipate and perform a public-speaking task. During anticipation, negative self-focused cognitions or relaxation were experimentally induced while self-reported anxiety, autonomic arousal (heart rate, heart rate variability, skin conductance level), and acoustic eye-blink startle response were assessed. As predicted, negative self-focused cognitions mediated the effects of trait social anxiety on self-reported anxiety and heart rate variability during negative anticipation. Furthermore, trait social anxiety predicted increased startle amplitudes. These findings support a central assumption of the cognitive model of social anxiety.     

The conjunction fallacy and the many meanings of and

According to the conjunction rule, the probability of A and B cannot exceed the probability of either single event. This rule reads and in terms of the logical operator wedge, interpreting A and B as an intersection of two events. As linguists have long argued, in natural language "and" can convey a wide range of relationships between conjuncts such as temporal order ("I went to the store and bought some whisky"), causal relationships ("Smile and the world smiles with you"), and can indicate a collection of sets rather than their intersection (as in "He invited friends and colleagues to the party"). When "and" is used in word problems researching the conjunction fallacy, the conjunction rule, which assumes the logical operator wedge, therefore cannot be mechanically invoked as a norm. Across several studies, we used different methods of probing people's understanding of and-conjunctions, and found evidence that many of those respondents who violated the conjunction rule in their probability or frequency judgments inferred a meaning of and that differs from the logical operator wedge. We argue that these findings have implications for whether judgments involving ambiguous and-conjunctions that violate the conjunction rule should be considered manifestations of fallacious reasoning or of reasonable pragmatic and semantic inferences.     

Attention capture by faces

We report three experiments that investigate whether faces are capable of capturing attention when in competition with other non-face objects. In Experiment 1a participants took longer to decide that an array of objects contained a butterfly target when a face appeared as one of the distracting items than when the face did not appear in the array. This irrelevant face effect was eliminated when the items in the arrays were inverted in Experiment 1b ruling out an explanation based on some low-level image-based properties of the faces. Experiment 2 replicated and extended the results of Experiment 1a. Irrelevant faces once again interfered with search for butterflies but, when the roles of faces and butterflies were reversed, irrelevant butterflies no longer interfered with search for faces. This suggests that the irrelevant face effect is unlikely to have been caused by the relative novelty of the faces or arises because butterflies and faces were the only animate items in the arrays. We conclude that these experiments offer evidence of a stimulus-driven capture of attention by faces.     

Centrifugal acceleration to 3Gz is related to increased release of stress hormones and decreased mood in men and women

It has been suggested that the central and peripheral neural processes (CPNP) are affected by gravitational changes. Based on the previous experiments during parabolic flights, central and peripheral changes may not only be due to the changed gravitational forces but also due to neuroendocrine reactions related to the psycho-physiological consequences of gravitational changes. The present study focuses on the interaction of neuroendocrine changes and the physical and mental states after acceleration to three-time terrestrial gravity (3Gz). Eleven participants (29.4+/-5.1 [SD] years (male (n=8): 30+/-5.1 years; female (n=3): 27.7+/-2.1 years) underwent a 15 min acceleration to 3Gz in a human centrifuge. Before and after the acceleration to 3Gz circulating stress hormone concentrations (cortisol, adrenocorticotropic hormone (ACTH), prolactin, epinephrine, norepinephrine) and perceived physical and mental states were recorded. A second control group of 11 participants underwent the same testing procedure in a laboratory session. Serum cortisol concentration during exposure to the centrifugal acceleration increased by 70%, plasma concentration of ACTH increased threefold, prolactin twofold, epinephrine by 70% and norepinephrine by 45%, whereas the perceived physical well-being decreased. These findings demonstrate that psycho-physiological changes have to be regarded as a relevant factor for the changes in CPNP during phases of hypergravity exposure.     

Stimulus frequency influences spontaneous perceptual reversals in ambiguous apparent motion

The temporal integration of continuous sensory information into a temporally extended percept becomes evident in spontaneous reversals of ambiguous apparent motion. To study the temporal relation of spontaneous percept reversals and temporal stimulus properties, we systematically varied presentation frequency in an ambiguous-apparent-motion paradigm. Moreover, we triggered percept reversals in a manner that was not consciously perceived by manipulating the duration of single frames. We found that the reversal rate depended on the stimulus frequency (with higher frequencies resulting in faster percept reversals) and that we could externally trigger perceptual reversals. Our findings support the idea that spontaneous reversals of ambiguous apparent motion are influenced by bottom-up effects at early processing levels. The paradigm allows for specific contrasts of spontaneous and externally triggered (but otherwise identical) perceptual reversals and, by this means, for further study of the underlying mechanisms.     

Trunk and center of mass movements during gait in children with juvenile idiopathic arthritis

Motion of the body center of mass (CoM) can often indicate the overall effect of the strategy of forward progression used. In the present study, focus is placed on trunk movements in the sagittal, coronal, and transverse/rotation plane, as well as placement of the CoM, during gait in children with juvenile idiopathic arthritis (JIA). Seventeen children with JIA, all with polyarticular lower extremity involvement were examined before and approximately two weeks after treatment with intra-articular cortico-steroid injections. Movement was recorded with a 6-camera 3D motion analysis system in both the children with JIA and in 21 healthy controls. Trunk and center of mass movements were compared between JIA and controls, and effects of intra-articular cortico-steroid treatment were evaluated. Children with JIA were more posteriorly tilted in the trunk, contrary to the common clinical impression, and had their CoM placed more posterior and off-centred, which may have been a result of pain. With such knowledge, it might be possible to better understand the effects of their pain and involvement, and ultimately to plan a treatment strategy for improving their gait patterns.