A common theme running through much of the visual recognition literature is that faces are special. Many studies now describe evidence for the idea that faces are processed in a dedicated center in cortex. Studies have also argued for the presence of evolutionarily expedient pathways dedicated to the processing of certain facial expressions. Evidence for this proposal comes largely from visual search tasks which have established that threatening expressions are more rapidly detected than other expressions: the 'face-in-the-crowd effect'. One open criticism of this effect is that it may be due to low-level visual artifacts, rather than biological preparedness. One attempt at controlling low-level differences has been to use schematic line-drawing versions of faces. This study aimed to discover if there might be alternative issues with schematic stimuli. The first study replicated the face-in-the-crowd threat advantage for schematic faces, but also measured a comparable effect using stimuli comprised of obliquely oriented lines. Similar results were achieved with these stimuli rotated, which had the effect of removing any residual resemblance to a face. The results suggest that low-level features probably underlie the face-in-the-crowd effect described for schematic face images, thereby undermining evidence for a search advantage for specific facial expressions.

Previous behavioural research (Land and Horwood in Nature 377:339-340, 1995) indicates that surprisingly little visual information is required to effect smooth and accurate steering through a curving roadway. Based on results from a driving simulator study, Land and Horwood reported that viewing the roadway through two horizontal apertures, one degree of visual angle in height, can result in steering performance which is indistinguishable from that obtained with the whole scene visible. The position of the apertures in the visual field, they claimed, is crucial; higher up leads to less accurate but more stable steering responses, whilst lower down leads to jerky steering but more accurate lane-keeping. These findings are consistent with a two-stage model of steering control proposed by Donges in Human Factors 20:691-707 (1978). However, in a driving simulator, the temporal lag between the input signal received from a control device and the output presented on the display can have profound effects on steering behaviour. In two experiments, we show that the effect of aperture position on steering accuracy and stability is pronounced when a slow frame update rate is used (7.2 Hz, as used by Land and Horwood in Nature 377:339-340, 1995), but largely attenuated with a faster update rate (72 Hz). These results are consistent with the broader empirical literature dealing with temporal delays in manual tracking, and urge a critical reappraisal of the behavioural evidence for the two-stage steering model.

When attempting to perform bi-phasic steering movements (such as a lane change) in the absence of visual and inertial feedback, drivers produce a systematic heading error in the direction of the lane change (Wallis et al., Curr Biol 12(4):295-299, 2002; J Exp Psychol Hum Percept Perform 33(55):1127-1144, 2007). Theories of steering control which employ exclusively open-loop control mechanisms cannot accommodate this finding. In this article we show that a similar steering error occurs with obstacle avoidance, and offer compelling evidence that it stems from a seemingly general failure of human operators to correctly internalise the dynamics of the steering wheel. With respect to lateral position, the steering wheel is an acceleration control device, but we present data indicating that drivers treat it as a rate control device. Previous findings from Wallis et al. can be explained the same way. Since an open-loop control mechanism will never succeed when the dynamics of the controller are internalised improperly, we go on to conclude that regular, appropriately timed sensory feedback-predominantly from vision-is necessary for regulating heading, even during well-practiced, everyday manoeuvres such as lane changing and obstacle avoidance.

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