Visual Marking of Locations and Feature Maps: Evidence from Within-dimension Defined Conjunctions

Recently, Watson and Humphreys (1997, 1998) proposed that the selection of new visual events can be aided by the top-down inhibition of old information-visual marking (VM) and that the mechanisms of marking differ for static and moving stimuli. Stationary stimuli are marked by location-based inhibition, whereas moving stimuli are marked by inhibition applied at the level of whole-feature maps. Here we provide a test of this 'two-mechanism' account. We show that static items can be marked even when old and new stimuli contain the same features and so cannot be distinguished by activation within a unique feature map. However, moving old items could not be marked unless they possessed a unique feature (colour). Manipulations of grouping strength, both within and between distractor sets, did not affect the basic findings. The results support the existence of two mechanisms for VM and counter an object-based inhibition explanation of performance.     

The Eysenck personality scales: stability and change after therapy.

Eysenck has linked personality theory with the aetiology and treatment of abnormal behaviour (Eysenck, 1970). At least four levels of explanation link hypothetical neurophysiological mechanisms to self-report measures of personality, laboratory task performance and observed social habits and attitudes (Eysenck, 1960). The phenomena of neurotic breakdown and recovery provide one natural test of predictions from personality theory with respect to neuroticism (N) and extraversion (E). Taking phobias as an example, it is predicted that persons with a high score on N (a low threshold for emotional activation) develop phobic reactions more readily, and the more introverted the person, the more quickly and strongly are the phobic reactions acquired and lastingly maintained (Eysenck and Rachman, 1965, p. 36).In a prospective study of university students. Kelvin et al. (1965) were unable to find a relationship between initial N score and psychological distress up to 2.5 years later. Rather, the N scale appeared to reflect current mental status, increasing when distress was reported. E scores also dropped in a group of students who happened to be referred to a psychiatrist. Similarly, in a 3-year follow-up of patients who had attended a psychiatrist. Ingham (1966) found that change in clinical status was reflected in a change of N, with the score of the improved group returning to the population mean. Initial personality did not predict change in clinical status. It was also found in a number of analyses that improvement was related to an increase in extraversion.The present study was designed to replicate Ingham's experiment on a more homogeneous group of neurotic patients—all phobic—who had received fantasy or in vivo exposure treatment (Marks, 1974). This treatment can be compared to an extinction procedure, i.e. the non-reinforced presentation of the CS, and should therefore provide a good testing ground of personality theory. Eysenck's theory predicts that the speed and success of treatment will be related to initial E and N scores. In particular, the speed of extinction of the neurotic fear should be related to extraversion; the more extraverted the patient the more rapidly should the fear extinguish.     

Courageous acts or courageous actors?

The title question was addressed by relating psychometric, psychiatric and field-performance measures obtained from a group of military bomb-disposal operators. The outstandingly successful operators in this highly competent group of soldiers were found to have some distinctive features. The excellent performance and personal stability of the group as a whole was noteworthy and may have precluded the emergence of more distinctive features of courage. Evidence was obtained of acts of courage and of courageous actors.     

Dissociating the effects of similarity, salience, and top-down processes in search for linearly separable size targets

In two experiments, we explored the role of foreknowledge on visual search for targets defined along the size continuum. Targets were of large, medium, or small size and of high or low similarity relative to the distractors. In Experiment 1, we compared search for known and unknown singleton feature targets as a function of their size and similarity to the distractors. When distractor similarity was high, target foreknowledge benefited targets at the end of the size continuum (i.e., large and small) relatively more than targets of medium size. In Experiment 2, participants were given foreknowledge of what the target was not The beneficial effect of foreknowledge for endpoint targets was reduced. The data indicate the role of top-down templates in search, which can be "tuned" more effectively for targets at the ends of feature dimensions.     

The time course of figure-ground reversal

We report the results from five experiments employing a modified version of the short-term visual matching (STVM) method introduced by Driver and Baylis (1996). In STVM, participants see a study display with ambiguous figure-ground relations. After the study display, participants have to decide which of two shapes in a match display was seen before in the study display. STVM has been used by Vecera, Vogel, and Woodman (2002) to demonstrate that the lower region is a figure-ground cue. In our modified version of STVM, the study stimulus was preceded by a brief prime. This caused a biasing of the figural interpretation of the ambiguous figure-ground displays that contained the lower region cue. We show that 100-msec priming with an unambiguous display is enough to affect the subsequent interpretation of the ambiguous figure-ground display. It takes maximally 350 msec to complete a transition from the nondominant interpretation to the dominant interpretation of an ambiguous figure-ground display that contains the lower region cue.     

Direct and indirect effects of action on object classification

We report three experiments in which name verification responses to either objects (Experiments 1 and 2) or hand movements (Experiment 3) were compared with action decisions, where participants verified whether an object is typically used in the way described by a verbal label. In Experiments 1 and 2, we report that action decisions show more consistent and larger effects of the congruency of either a handgrip or a type of movement than do name verification responses, although there was some effect of the congruency of the handgrip on name verification. In Experiment 3, we demonstrate that the congruency of the object being moved affects both action and name verification responses to hand movements. We discuss the]data relative to accounts of how actions and names are accessed by visually presented objects and in relation to work on the information called upon in classification tasks.     

Driving attention with the top down: The relative contribution of target templates to the linear separability effect in the size dimension

Bauer, Jolicoeur, and Cowan (1996a, 1996b, 1998) have shown that visual search for a target among distractors is apparently serial if the target is nonlinearly separable from the distractors in a particular feature space (e.g., color or size). In contrast, if the target is linearly separable from the distractors, search is relatively easy and seemingly spatially parallel. We examined the contribution of top-down knowledge of the target to the linear separability effect on search. Two visual search experiments were conducted using small, medium, or large circles as targets. In the first experiment, participants could use knowledge of the target to guide search, whereas, in the second, the target was unknown on each trial. Search for a medium (nonlinearly separable) target among small or large distractors benefited least from knowledge of the target as compared with search for a small or large target. Thus, the linear separability effect can be determined in part by use of top-down knowledge to facilitate the detection of targets at the ends of a continuum defining the stimuli.     

Understanding emotion: lessons from anxiety

We agree that conceptualisation is key in understanding the brain basis of emotion. We argue that by conflating facial emotion recognition with subjective emotion experience, Lindquist et al. understate the importance of biological predisposition in emotion. We use examples from the anxiety disorders to illustrate the distinction between these two phenomena, emphasising the importance of both emotional hardware and contextual learning.     

Immediate small number perception: evidence from a new numerical carry-over procedure

Evidence is presented for the immediate apprehension of exact small quantities. Participants performed a quantification task (are the number of items greater or smaller than?), and carry-over effects were examined between numbers requiring the same response. Carry-over effects between small numbers were strongly affected by repeats of pattern and number identity relative to when displays were from the same response category but contained different numbers. Carry-over effects with large items were less sensitive to both pattern and number identity, even when the numbers in the small and large categories were matched for discriminability. The data suggest that small numbers are immediately apprehended through a direct subitization process distinct from pattern recognition and the apprehension of approximate number.