Configuration perception and face memory,and face context effects in developmental prosopagnosia

This study addresses two central and controversial issues in developmental prosopagnosia (DP), configuration- versus feature-based face processing and the influence of affective information from either facial or bodily expressions on face recognition. A sample of 10 DPs and 10 controls were tested with a previously developed face and object recognition and memory battery (Facial Expressive Action Stimulus Test, FEAST), a task measuring the influence of emotional faces and bodies on face identity matching (Face–Body Compound task), and an emotionally expressive face memory task (Emotional Face Memory task, FaMe-E). We show that DPs were impaired in upright, but not inverted, face matching but they performed at the level of controls on part-to-whole matching. Second, DPs showed impaired memory for both neutral and emotional faces and scored within the normal range on the Face–Body Compound task. Third, configural perception but not feature-based processing was significantly associated with memory performance. Taken together the results indicate that DPs have a deficit in configural processing at the perception stage that may underlie the memory impairment.     

Perceptual separability of featural and configural information in congenital prosopagnosia

The deficit in face recognition in individuals with prosopagnosia has often been attributed to an underlying impairment in holistic processing. Exactly what constitutes holistic processing has remained controversial, however. Here, we compare how configural information and featural information interact during face processing in a group of individuals with congenital prosopagnosia (CP) and matched controls. We adopted Amishav and Kimchi's version of Garner's speeded classification task, in which observers classify upright faces based on configural (intereyes and nose–mouth spacing) or featural (shape of eyes, nose, and mouth) information while the other dimension remains constant or varied randomly. We replicated the finding that normal observers evince symmetric Garner interference—failure to selectively attend to features without being influenced by irrelevant variation in configuration, and vice versa—indicating that featural and configural information are integral in normal face processing. In contrast, the CPs showed no Garner interference: They were able to attend to configural information without interference from irrelevant variation in featural information, and they were able to attend to featural information without interference from irrelevant variation in configural information. The absence of Garner interference in CP provides strong evidence that featural information and configural information are perceptually separable in CP's face processing. These findings indicate that CPs do not perceive faces holistically; rather, they process featural and configural information independently.     

Effects of facial expression on shared attention mechanisms

We investigated the effects of facial expression on shared attention mechanisms. A female or male facial stimulus with one of 3 facial expressions (happiness, neutral, or anger) was presented at the center of a display. This facial stimulus gazed toward a subject, or toward the left or right side of the display. After the facial stimulus was offset, a target appeared on the left or right side of the display and the reaction time to the target was measured. In the statistical analysis by ANOVA, there was a significant main effect of congruity between the target position and the gaze direction in both the female and male facial cues, indicating that gaze direction significantly affected reaction time. When the female facial cues were presented, the reaction times for the congruent target position to the gaze direction were significantly shorter in the happy than other facial expressions. However, there were no significant differences in reaction time when the facial stimuli were presented in an inverted orientation. The results demonstrated that facial expression significantly affected shared attention mechanisms.     

The observer observed: Frontal EEG asymmetry and autonomic responses differentiate between another person's direct and averted gaze when the face is seen live

Recently, we showed that another person's gaze direction influenced the perceiver's frontal EEG asymmetry and autonomic arousal in response to freely viewed real faces, but not in response to face pictures. However, the lack of a task during the viewing may have resulted in less attention allocation to face pictures vs. live faces. In the present study, the participants performed two online tasks while viewing the faces presented live through an electronic shutter and as pictures on a computer screen. The results replicated those from our previous experiment showing that direct gaze elicited greater relative left-sided frontal EEG asymmetry and autonomic arousal than averted gaze but, again, only in the live condition. However, the results also showed that two live stimulus faces (male and female) elicited differential EEG asymmetry responses in our participants (all females), and the effects of gaze direction were observed only for the (live) female faces. The results suggest that the discriminative responses to live faces vs. pictures are likely to reflect the participants' enhanced mental-state attributions and self-awareness when looking at and being looked by live faces. Thus, the motivation- and affect-related psychophysiological responses to gaze direction are most discriminative in the presence of another person, regardless of whether the face/gaze is actively monitored or not.     

Aging effects on early-stage face perception: An ERP study

We compared early stages of face processing in young and older participants as indexed by ERPs elicited by faces and non-face stimuli presented in upright and inverted orientations. The P1 and N170 components were larger in older than in young participants. However, the early distinction between stimulus categories as reflected by N170 face was similar across groups. Face inversion increased and delayed the N170 peak in the younger group while in older participants inversion delayed the N170 peak but had no effect on amplitude. The N170 amplitude was right-lateralized in the young, but not in the older group. Yet, the difference between the N170 elicited by faces and non-face stimuli was similarly right-lateralized in both groups. These data suggest that detection of faces and their streaming to face-characteristic structural encoding is not altered by age. In contrast, the absence of face-inversion effects on N170 amplitudes in the elderly suggest that face individuation, which is probably the default strategy in younger people, might not be attempted by default in older people, at least when they look at young faces.     

The perceived duration of emotional face is influenced by the gaze direction

The present research investigates the effects of gaze direction on the perceived duration of the presentation of angry and happy expressions. When the facial expression was angry, a straight gaze elongated the perceived duration of the expression compared with an averted gaze. However, there was no effect of gaze direction when the facial expression was happy. These findings indicate that the subjective estimation of time is elongated when the observer encounters a socially important survival signal, considering that an angry face with a straight gaze may be perceived as a threat requiring a fight-or-flight response.     

The effect of face inversion on intracranial and scalp recordings of event-related potentials

The face inversion effect (FIE) refers to a disproportionate disruption of the processing of face information by inverting faces. We investigated the FIE in epilepsy patients by simultaneous intracranial and scalp recordings of event-related potentials (ERPs). In scalp recordings, a typical FIE on ERPs was observed with increased latencies and amplitudes of the positive counterpart of the occipito-temporal N170, namely, the vertex positive potential (VPP), in response to inverted faces. Similar amplitude and latency increases were revealed for the intracranial N200 recorded over face-sensitive and non-face-sensitive areas in the lateral occipital cortex, but not in the ventral temporal cortex. Peak latencies did not differ between the scalp VPP and intracranial N200. Findings indicate that the lateral occipital cortex but not the ventral temporal cortex contributes primarily to the FIE observed in scalp recordings.     

倒位携带者遗传学及临床效应分析

目的研究染色体倒位的遗传效应,探讨染色体倒位对携带者生育的影响。方法取患者外周血淋巴细胞按实验室常规染色体标本制备方法进行G-显带,9号染色体倒位者,则加做C带进行染色体核型分析以证实之。结果经G-显带和C-显带分析,11313例患者中共有128例为倒位携带者,发生率为1.13%,涉及的染色体有1-4,7,9-11和Y。其中以9号染色体臂间倒位的发生率最高,其次为Y染色体。9号染色体臂间倒位者有87例,发生率为0.77%,占倒位携带者的67.96%;Y染色体臂间倒位者有19例,发生率为0.17%,占倒位携带者的14.84%。结论染色体倒位是否对生育有影响目前尚无定论,但是对倒位携带者依据其病史及家族史给予正确的遗传咨询以指导临床是必要的。     

Double dissociation of configural and featural face processing on P1 and P2 components as a function of spatial attention

Face recognition relies on both configural and featural processing. Previous research has shown that P1 is sensitive to configural face processing, but it is unclear whether any component is sensitive to featural face processing; moreover, if there is such a component, its temporal sequence relative to P1 is unknown. Thus, to avoid confounding physical stimuli differences between configural and featural face processing on ERP components, a spatial attention paradigm was employed by instructing participants to attend an image stream (faces and houses) or an alphanumeric character stream. The interaction between attention and face processing type on P1 and P2 components indicates different mechanisms of configural and featural face processing as a function of spatial attention. The steady‐state visual evoked potential (SSVEP) results clearly demonstrated that participants could selectively attend to different streams of information. Importantly, configural face processing elicited a larger posterior P1 (approximately 128 ms) than featural face processing, whereas P2 (approximately 248 ms) was greater for featural than for configural face processing under attended condition. The interaction between attention and face processing type (configural vs. featural) on P1 and P2 components indicates that there are different mechanisms of configural and featural face processing operating as functions of spatial attention. While the P1 result confirms previous findings separating configural and featural face processing, the newly observed P2 finding in the present study extends this separation to a double dissociation. Therefore, configural and featural face processing are modulated differently by spatial attention, and configural face processing precedes featural face processing.     

平衡易位和倒位携带者对子代的影响

目的研究平衡易位和倒位携带者对下一代的影响.方法对94例染色体异常者,其中平衡易位70例、倒位携带者24例的妊娠结果进行分析.结果94例染色体异常者,其中70例平衡易位携带者流产或死胎、生育畸形儿、平衡易位携带者及生育正常儿的机会分别为:68.86%、8.33%、11.84%、10.09%;24例倒位携带者流产或死胎、生育畸形儿、倒位携带者及生育正常儿的机会分别为:35.29%、23.53%、21.53%、19.61%.结论平衡易位和倒位携带者,因产生不平衡配子而导致反复流产、死胎、生育畸形儿和染色体异常携带者的风险很大.     

Face recognition impairments despite normal holistic processing and face space coding: Evidence from a case of developmental prosopagnosia

Holistic processing and face space coding are widely considered primary perceptual mechanisms behind good face recognition. Here, however, we present the case of S.P., a developmental prosopagnosic who demonstrated severe impairments in face memory and face perception, yet showed normal holistic processing and face space coding. Across three composite experiments, S.P. showed normal-strength holistic processing for upright faces and no composite effect for inverted faces. Across five aftereffect experiments, S.P. showed normal-sized face aftereffects, which derived normally from face space rather than shape-generic mechanisms. The case of S.P. implies: (a) normal holistic processing and face space coding can be insufficient for good face recognition even when present in combination; and (b) the focus of recent literature on holistic processing and face space should be expanded to include other potential face processing mechanisms (e.g., part-based processing). Our article also highlights the importance of internal task reliability in drawing inferences from single-case studies.     

The effect of numeracy on the comprehension of information about medicines in users of a patient information website

Objective

To investigate the relationship between numeracy and the accuracy of side effect risk estimation following the presentation of information about a medicine via the Cancer Research UK (CR-UK) patient information website.

Methods

591 website users were presented with information in different formats about the risks of side effects from taking tamoxifen. Participants estimated the risk of each side effect, provided other subjective ratings about the information and completed a numeracy task.

Results

Regardless of presentation format, numeracy was correlated with the accuracy of three side effect risk estimates. People with cancer and tamoxifen users showed stronger correlations for all side effect estimates. In addition, numeracy was positively related to the perceived influence of the information on the decision to take the medicine and was negatively related to ratings of satisfaction with the information.

Conclusion

People with a lower numeracy level make larger errors in interpreting medicines side effect risk information.

Practice implications

Pharmacists, other health professionals and patient information websites should ensure they provide clear explanations of risk, particularly to people with low numeracy, and assess their understanding of those explanations. Future research into risk communication should take account of numeracy level, to investigate the impact of different formats.     

The effect of enslaving on perception of finger forces

The primary purpose was to examine the effect of enslaving on finger force perception during isometric finger force production using an ipsilateral force-matching paradigm. Fourteen subjects were instructed to produce varying levels of reference forces [10, 20, 30, and 40% maximal voluntary contraction (MVC)] force using one finger (index, I or little, L) and to reproduce these forces using the same finger (homo-finger tasks, I/I and L/L) or a different finger (hetero-finger tasks, I/L and L/I). Forces of all fingers were recorded. During homo-finger tasks, no differences were found in force magnitude or relative level of force (expressed as a proportion of MVC). The index finger matching force magnitudes were greater than the little finger reference force magnitudes, with significantly lower levels of relative force during L/I tasks; while the little finger matching forces underestimated the index finger reference forces with significantly higher levels of relative force during I/L tasks. The difference in the matching and reference forces by the instructed finger(s), i.e., matching error, was larger in hetero-finger tasks than in homo-finger tasks, particularly at high reference force levels (30, 40% MVC). When forces of all fingers were considered, enslaving (uninstructed finger forces) significantly minimized matching errors of the total force during both I/L and L/I hetero-finger tasks, especially at high reference force levels. Our results show that there is a tendency to match the absolute magnitude of the total force during ipsilateral finger force-matching tasks. This tendency is likely related to enslaving effects. Our results provide evidence that all (instructed and uninstructed) finger forces are sensed, thus resulting in perception of the absolute magnitude of total finger force.     

The N2pc component in ERP and the lateralization effect of language on color perception

This study examined the electrophysiological bases of the effect of language on color perception. In a visual search task, a target was presented to the left or right visual field. The target color was either from the same category as a set of distractors (within-category condition) or from a different category (between-category condition). For both category conditions, the targets elicited a clear N2pc (N2-posterior-contralateral) component in the event-related potential (ERP) in the contralateral hemisphere. In the left hemisphere only, the N2pc amplitude for the between-category condition was larger than that for the within-category condition. These results indicate that the N2pc could be used as an index to describe the lateralization effect of language on color perception.     

Functional asymmetry and interhemispheric cooperation in the perception of emotions from facial expressions

The present study used the redundant target paradigm on healthy subjects to investigate functional hemispheric asymmetries and interhemispheric cooperation in the perception of emotions from faces. In Experiment 1 participants responded to checkerboards presented either unilaterally to the left (LVF) or right visual half field (RVF), or simultaneously to both hemifields (BVF), while performing a pointing task for the control of eye movements. As previously reported (Miniussi et al. in J Cogn Neurosci 10:216-230, 1998), redundant stimulation led to shorter latencies for stimulus detection (bilateral gain or redundant target effect, RTE) that exceeded the limit for a probabilistic interpretation, thereby validating the pointing procedure and supporting interhemispheric cooperation. In Experiment 2 the same pointing procedure was used in a go/no-go task requiring subjects to respond when seeing a target emotional expression (happy or fearful, counterbalanced between blocks). Faster reaction times to unilateral LVF than RVF emotions, regardless of valence, indicate that the perception of positive and negative emotional faces is lateralized toward the right hemisphere. Simultaneous presentation of two congruent emotional faces, either happy or fearful, produced an RTE that cannot be explained by probability summation and suggests interhemispheric cooperation and neural summation. No such effect was present with BVF incongruent facial expressions. In Experiment 3 we studied whether the RTE for emotional faces depends on the physical identity between BVF stimuli, and we set a second BVF congruent condition in which there was only emotional but not physical or gender identity between stimuli (i.e. two different faces expressing the same emotion). The RTE and interhemispheric cooperation were present also in this second BVF congruent condition. This shows that emotional congruency is the sufficient condition for the RTE to take place in the intact brain and that the cerebral hemispheres can interact in spite of physical differences between stimuli.     

The effect of intervening forces on finger force perception

The purpose of the present study was to investigate the effect of intervening forces on the estimation of finger forces. To do this, we introduced intervening forces during a delayed force matching task. The basic idea in the present study was that when a reference force (or to-be-remembered force) is followed by another force, this second force (i.e., intervening force) will interfere with the estimation of the reference force. Subjects performed a modified delayed force matching task using the index finger of their dominant hand. This study consisted of eight experimental conditions which combined two reference forces (i.e., 10 and 30% MVCs) with four intervening forces (i.e., No, Half, Same and Double the reference force). The main finding of the present study was that the matching performance was systematically affected by intervening forces. The results showed that the reference force was underestimated in the condition where the intervening force was half the reference force, and overestimated in the condition where the intervening force was double the reference force. When the reference and intervening forces were the same, no intervening force effect was found. The effect of intervening force was explained by a distortion of force memory.     

The N400-concreteness effect reflects the retrieval of semantic information during the preparation of meaningful actions

The present ERP study investigated when and how action semantics, i.e. the conceptual knowledge that we acquired over the course of our lives, is activated during the preparation of object-directed actions. Subjects were required to grasp one of two objects and were implicitly instructed to either perform a meaningful action (e.g. moving a cup towards the mouth) or a meaningless action with the object (e.g. moving a cup towards the eye). A larger anterior N400 was found for the preparation of meaningful compared to meaningless actions, likely reflecting the retrieval of action semantic information in case a meaningful action was required with the object. The distribution and the latency of the anterior N400-effect were strongly related to standard N400-repetition effects, thereby further corroborating the semantic nature of the effect. In sum, the present study provides new insight in the neural and temporal dynamics underlying semantics for action.     

Amblyopic processing of positional information. Part I: Vernier acuity

Summary Psychometric functions for the recognition of vernier displacements have been measured in 6 strabismic amblyopes, 1 anisometropic amblyope, and 1 bilateral amblyope of unknown aetiology. In the non-amblyopic eyes of the 7 unilateral amblyopes the mean threshold vernier offset was about half of that of a group of 7 experienced normal observers. No correlation was found between vernier acuities and Snellen acuities in the abnormal eyes of squinters. These eyes also displayed massive distortions of horizontal spatial values causing perceptual distortions. In all but one of the amblyopic eyes tested hyperacuity virtually disappeared at the brief exposure duration of 50 ms. None of the observed effects could be predicted from the amblyopic contrast sensitivities, grating resolutions, or letter acuities. This suggests that the loss of positional information is an independent and most significant feature of amblyopic visual dysfunction.Study supported by Deutsche Forschungsgemeinschaft Re 337/4-1     

The effect of frequency on the visual perception of relative phase and phase variability of two oscillating objects

Relative phase has been studied extensively as a measure of interlimb coordination. Only two relative phases, namely 0 degrees and 180 degrees, are stably produced at the preferred frequency (approximately 1 Hz). When frequency is increased, movement at 180 degrees becomes unstable and relative phase typically switches to 0 degrees, which remains stable at higher frequencies. The current study was designed to investigate the perception of relative phase and of phase variability. Observers viewed two circles moving rhythmically in a computer display. Mean phases varied from 0 degrees to 180 degrees in 30 degrees steps. Phase variability at each mean phase varied from 0 degrees to 5 degrees, 10 degrees, and 15 degrees phase standard deviation (SD). Frequency of oscillation was either 0.75 Hz or 1.25 Hz. One group of ten observers judged mean relative phase. Another group judged phase variability. As predicted, increase in frequency yielded an increase in perceived phase variability at 180 degrees mean phase and other mean phases, but not at 0 degrees mean phase. In contrast, increase in actual phase variability affected judgments of 0 degrees mean phase most strongly. A second control experiment showed that the frequency effects were not produced by changes in display durations or frames per cycle of oscillation. The results are consistent with those in studies of interlimb coordination and indicate that understanding of interlimb coordination requires further investigation of phase perception.     

The genetic correlation between intelligence and speed of information processing

This study examined the contributions of genetic and environmental factors to the observed correlation between intelligence test scores and speed of information processing, based on data for same-sex adult twin pairs (age, 15–57). Verbal and performance IQ scores from the Multidimensional Abilities Battery, as well as 11 reaction-time measures derived from a battery of information-processing tasks, were available for 50 monozygotic and 32 dizygotic pairs of twins. Multivariate biometrical analyses were used to estimate genetic and environmental parameters underlying observed variances and covariances among intelligence test scores and a general speed of information-processing factor (based on a linear composite of the 11 reaction-time scores). A common-factor model with loadings on general speed of processing, verbal IQ, and performance IQ fit the data well. The common factor was influenced primarily by additive genetic effects, such that the observed relationships among the speed and IQ measures are mediated entirely by hereditary factors. There was additional specific genetic variance for Verbal IQ and specific shared-twin environmental variance for Performance IQ. However, twin similarity for general speed of processing was explained entirely by genetic factors related to intelligence. The results emphasize the importance of common, heritable, biological mechanisms underlying the speed-IQ association.This research was supported by funding from the Pioneer Fund, Inc.