The time course of processing external and internal features of unfamiliar faces

The time course of processing internal and external facial features was studied in a sequential face matching task, where first a target face was presented, followed by a test face. The exposure duration of the test face was varied systematically (90, 120, 150ms, and self-paced). In three tasks, participants were instructed to match either the whole face, only external features, or only internal features of the target and test face. Taken together, the results in all the three tasks provide evidence for very fast matching processes. For upright faces, maximal performance was achieved at 90ms exposure duration and longer exposure durations (120, 150ms, self-paced) did not improve accuracy. For inverted whole faces, reduced exposure duration resulted in an increase of matching errors, suggesting that below 150ms of exposure duration, inverted faces cannot be matched reliably. When matching selected facial features only, no such inversion effect was found. Our data challenges previous claims that external features are matched faster than internal: no difference of time course was found between external and internal features. However, external features were matched more accuratel

The inversion effect on gaze perception reflects processing of component information

When faces are turned upside-down they are much more difficult to recognize than other objects. This "face inversion effect” has often been explained in terms of configural processing, which is impaired when faces are rotated away from the upright. Here we report a "gaze inversion effect” and discuss whether it is related to configural face processing of the whole face. Observers reported the gaze locations of photographed upright or inverted faces. When whole faces were presented, we found an inversion effect both for constant errors and observer sensitivity. These results were closely replicated when only the eyes were visible. Together, our findings suggest that gaze processing is largely based on component-based information from the eye region. Processing this information is orientation-sensitive and does not seem to rely on configural processing of the whole fac

Does musical training improve school performance?

In a retrospective study, we compared school performance of 53 children practicing music (group1) with 67 controls not practicing music (group2). Overall average marks as well as average marks of all school subjects except sports were significantly higher in children who do (group1) than in those who do not practice music (group2). In a multiple regression analysis, musical training, parent's income, and educational level (grades) correlated significantly with overall average marks. A slight decrease of overall average marks over 4years from grades3 to 6 was found in the control group only. Musical training evidently correlates with children's better performance at school, but is obviously part of a multifactorial dependence. Continuous musical training appears to help achieve and maintain school performance at a high level over tim

Evaluating the two-component inspection model in a simplified luggage search task

Visual inspection of X-ray images of luggage is a time-pressured task that typically shows large initial training effects, but there exists a paucity of models capable of evaluating performance and speed concurrently. In the present study, visual inspection ability during learning was modeled using Drury's two-component inspection model (TCM; Drury, 1975) in a laboratory experiment involving 12 younger (mean age = 20.8 years) and 12 older (mean age = 60.0 years) naive participants undertaking a simplified luggage search task. Model fits and assumptions were found to be reliable and accurately reflected improvement with training for decision time, although neither search nor decision components of the model individually showed a significant effect of age. The decision component of the model showed larger improvement with training than did the search component, and stopping-time policy accurately reflected the improvements found between ages and within training levels. The TCM is a useful supplement to detection theory when speed of performance is a facto

The time course of processing external and internal features of unfamiliar faces

The time course of processing internal and external facial features was studied in a sequential face matching task, where first a target face was presented, followed by a test face. The exposure duration of the test face was varied systematically (90, 120, 150ms, and self-paced). In three tasks, participants were instructed to match either the whole face, only external features, or only internal features of the target and test face. Taken together, the results in all the three tasks provide evidence for very fast matching processes. For upright faces, maximal performance was achieved at 90ms exposure duration and longer exposure durations (120, 150ms, self-paced) did not improve accuracy. For inverted whole faces, reduced exposure duration resulted in an increase of matching errors, suggesting that below 150ms of exposure duration, inverted faces cannot be matched reliably. When matching selected facial features only, no such inversion effect was found. Our data challenges previous claims that external features are matched faster than internal: no difference of time course was found between external and internal features. However, external features were matched more accuratel

Symptoms, toxicities, and analytical results for a patient after smoking herbs containing the novel synthetic cannabinoid MAM-2201

We report a case of intoxication by the synthetic cannabinoid MAM-2201 ([1-(5-fluoropentyl)-1H-indol-3-yl](4-methyl-1-naphthalenyl)-methanone). A 31-year-old man smoked about 300mg of a herbal blend. He experienced an acute transient psychotic state with agitation, aggression, anxiety, and vomiting associated with a sympathomimetic syndrome. MAM-2201 was detected and quantified in a plasma sample using liquid chromatography-tandem mass spectrometry (LC-MS-MS). The level was 49ng/ml 1h after smoking. The use of other drugs was analytically excluded. The presence of MAM-2201 was confirmed in the herbal blend using gas chromatography-mass spectrometry (GC-MS) and LC-high resolution MS. This is the first description of an analytically confirmed intoxication and of the determination of MAM-2201 in human blood plasm

Configural processing and perceptions of head tilt.

Configural processing is important for face recognition, but its role in other types of face processing is unclear. In the present study, participants made judgments of head tilt for faces in which the vertical position of the internal facial region was varied. We found a highly reliable relationship between inner-face position and perceived head tilt. We also found that changes in inner-face position affected the perceived dimensions of an individual unchanged facial feature: compared to control faces, nearly two-thirds of faces in which the features had been moved down were judged to have a longer nose. This finding suggests an early integration of configural and featural processing to create a stable holistic percept of the face. The demonstration of holistic processing at a basic perceptual level (as opposed to during face recognition) is important as it constrains possible models of the relationships between featural and configural processing

Expertise, Automation and Trust in X-Ray Screening of Cabin Baggage

X-ray screening of passenger baggage is a key component in aviation security. The current study investigated how experts and novices performed in an X-ray baggage screening task while being assisted by an adaptable diagnostic aid. Furthermore, it examined how both groups operated and trusted this automated system. 30 experts (certified screeners) and 31 novices (students) had to indicate whether a target item (either a knife or a gun) was present in a series of X-ray images of cabin baggage. Half of the participants could choose between three different support levels of the diagnostic aid (DA): (1) no support, (2) a cue indicating the presence of a potential target without locating it, or (3) a cue indicating the presence of a potential target by surrounding it with a red frame. As expected, experts achieved higher detection performance (d’), were more self-confident and felt more competent in achieving the task than novices. Furthermore, experts experienced less time pressure and fatigue. Although both groups used the DA in a comparable way (in terms of support level used and frequency of level switches), results showed a performance increase for novices working with the DA compared to novices without support. This benefit of DA was not observed for experts. Interestingly, despite no difference in perceived trust ratings, experts were more compliant (i.e., following DA recommendations when it indicated the presence of a target) and reliant (i.e., following DA recommendations when it indicated the absence of a target) than novices. Altogether, the results of the present study suggested that novices benefited more from a DA than experts. Furthermore, compliance and reliance on DA seemed to depend on expertise with the task. Since experts should be better at assessing the reliability of the DA than novices, they may have used the DA as ‘back-up’ to confirm their decisions based on expertise (confirmatory function), while novices may have used it as a guide to base their decisions on (support function). Finally, trust towards a DA was associated with the degree to which participants found the DA useful

Visual search in ecological and non-ecological displays: Evidence for a non-monotonic effect of complexity on performance

Copyright @ 2013 PLoSThis article has been made available through the Brunel Open Access Publishing Fund.Considerable research has been carried out on visual search, with single or multiple targets. However, most studies have used artificial stimuli with low ecological validity. In addition, little is known about the effects of target complexity and expertise in visual search. Here, we investigate visual search in three conditions of complexity (detecting a king, detecting a check, and detecting a checkmate) with chess players of two levels of expertise (novices and club players). Results show that the influence of target complexity depends on level of structure of the visual display. Different functional relationships were found between artificial (random chess positions) and ecologically valid (game positions) stimuli: With artificial, but not with ecologically valid stimuli, a “pop out” effect was present when a target was visually more complex than distractors but could be captured by a memory chunk. This suggests that caution should be exercised when generalising from experiments using artificial stimuli with low ecological validity to real-life stimuli.This study is funded by Brunel University and the article is made available through the Brunel Open Access Publishing Fund