How is gait visually regulated when the head is travelling faster than the legs?

Gait regulation patterns were examined under various visual conditions in order to determine whether speed information provided by peripheral vision is taken into account in gait adjustments. Nine subjects walking toward a visual target on the ground were required to place one foot exactly on it. peripheral vision was either restricted to a 12 degrees angle or decorrelated, corresponding to a moving speed greater than the actual walking speed. Decorrelation was obtained by placing the subject on a treadmill moving in the walking direction. The results show, by comparison with the control condition, that the restriction of peripheral visual information did not affect the accuracy of the foot positioning, whereas decorrelated conditions affected it significantly: we noted that the gait regulation was triggered early on and showed a very stable pattern so that the distance to the target was consistently underestimated. This suggest that, although visual speed information is not indispensable in this kind of task, it is nevertheless taken into account in stride adjustments when the whole visual field is available. The results are discussed, in the context of a time-based approach to locomotor activity, in relation to the possible visual methods that might be used in obtaining information about time to contact the target.     

Does switching between strategies within the same task involve a cost?

In two experiments, participants had to switch regularly between two cognitive strategies of a different complexity in the context of a numerosity judgement task. Expt 1 comprised bivalent stimuli (i.e. allowing the application of the two strategies), whereas Expt 2 involved univalent stimuli (i.e. allowing the application of only one strategy). Both experiments revealed that switching between strategies entailed a cognitive cost that was reflected in longer response times on switch compared to non‐switch trials but not in reduced accuracy. The size of this switch cost did not differ as a function of strategy complexity but tended to diminish as a strategy became more appropriate for solving a particular problem. We discuss the extent to which current theories of task switching can account for these findings.     

Sad people avoid the eyes or happy people focus on the eyes? Mood induction affects facial feature discrimination

Depressed people tend to avoid eye-contact in social situations and in experimental settings, whereas happy people actively seek eye-contact. We report an experiment in which participants made discriminations between faces that had either configural or featural changes made to the eyes, nose, or head shape. The results showed participants induced to be happy detected changes in eyes more often than participants induced to be sad, but failed to detect changes in other facial features. Sad-induced participants detected changes to the head shape but not the eyes. The results are interpreted in terms of differential use of features attended to by happy and sad participants, whereby happy people are more likely to attend to eyes during face perception than sad people.     

When are semantic targets detected faster than visual or acoustic ones?

Duration-discrimination data from an experiment using empty auditory intervals in a two-alternative forced-choice paradigm are presented. The observed functional relationship between standard deviation of the psychometric density function and stimulus duration is shown to be fit significantly better by a Weber’s law model of duration discrimination than by Creelman’s counter model. Both models fail to predict the rapid rise in the Weber fraction observed for durations longer than about 2 sec. However, the Weber’s law model, based on a generalization of Weber’s law, accurately predicts the initial drop in the Weber fraction for very short durations and the observed constancy of the Weber fraction for durations up to 2 sec.     

Transfer in discrimination learning: Do children mediate more than adults?

A series of four-dimensional, discrimination-learning problems were presented to second-, sixth-, eighth-, and twelfth-grade students (ages 7, 11, 13, and 17 years, respectively). One pretraining problem, using different dimensions, preceded the four experimental problems; these employed identical dimensions and stimulus values. Solutions were selected without dimensional replacement.Blank-trial probes enabled detection of initial predictions. Results clearly indicated that (1) older subjects made dramatically fewer intradimensional predictions (utilizing the solution dimension from the preceding problem) than did younger subjects, (2) all age groups demonstrated systematic changes over problems; these reflected the specific solution sequence experienced, and (3) there were consistent developmental differences in the speed with which subjects noted and utilized regularities across problems.The pattern of data is not congruent with the expectations of mediation theory. However, it is in accord with the transfer hypothesis, which is a recent extension of hypothesis theory. The transfer hypothesis provides a theoretical framework which suggests when we should observe “mediational” behavior (i.e., intradimensional transfer) and when to expect the inverse.     

Are three-sample tasks less sensitive than two-sample tasks? Memory effects in the testing of taste discrimination

In order to provide insights into why discrimination protocols with three stimuli sometimes tend to be less sensitive than protocols with two stimuli, two experiments were conducted. In these experiments, the relative effects of memory decay and memory interference were investigated. Both experiments involved purified water and/or solutions of low NaCl concentration. In Experiment 1, three protocols were compared: the traditional same-different test (Protocol 1), the same protocol with a rinse between the two samples (Protocol 2), and Protocol 2 with an added time delay between the first sample and the intermediate rinse (Protocol 3.) The decrease in measured d' values as time delay increased indicated that memory decay might be a factor for tests with three stimuli, such as the triangle method, rendering it less sensitive than tests with two stimuli, such as the same-different method. In Experiment 2, four protocols were compared: the traditional same-different test, the two-rinse same-different test, the triangle test, and what will be called duo same-different test. The experimental design allowed the individual consideration of memory decay and interference effects. From this last experiment, the substantial effect of memory interference was uncovered. Further experimentation will be necessary to estimate the exact relative effects of memory interference and memory decay.     

Is the discrimination of motion-path length unique?

Discrimination of the extent of a motion path may present a special problem since the discrimination calls on memory for changing position and involves pursuit movements of the eye. To determine how these factors affect judgment, discrimination of extents represented by motion paths, successively appearing endpoints, and simultaneously present endpoints was compared under a variety of eye-movement conditions: fixation, pursuit, and saccadic. Discrimination was assessed by the method of adjustment and also by the method of magnitude estimation. Discrimination of motion path extent was found to be as accurate as discrimination of an interspace demarcated by simultaneously presented points or by successively presented points. This was true for brief single presentations of the extents as well as for repeated exposures to the extents. The findings were applied to the analysis of the perception of velocity and the perception of extent.     

Positive facial expressions are recognized faster than negative facial expressions, but why?

Three experiments examined the recognition speed advantage for happy faces. The results replicated earlier findings by showing that positive (happy) facial expressions were recognized faster than negative (disgusted or sad) facial expressions (Experiments 1 and 2). In addition, the results showed that this effect was evident even when low-level physical differences between positive and negative faces were controlled by using schematic faces (Experiment 2), and that the effect was not attributable to an artifact arising from facilitated recognition of a single feature in the happy faces (up-turned mouth line, Experiment 3). Together, these results suggest that the happy face advantage may reflect a higher-level asymmetry in the recognition and categorization of emotionally positive and negative signals.     

When can an object feel heavier than itself? Perceived heaviness of a wielded object depends on grasp position

Perceived heaviness is a function of how an object resists being moved, and such resistance is determined by object mass and the distribution of that mass relative to the wrist. Whereas mass is independent of grasp position on an object, distribution of mass relative to the wrist is not. Therefore, perceived heaviness should vary with grasp position. Blindfolded participants wielded internally weighted cylindrical objects while grasping them at different distances from the centre of mass. They rated how heavy each object felt at each location relative to a standard object. The results show that objects felt heavier as they were grasped farther from the centre of mass, highlighting the role of the touch system in controlling movement.     

What drives the organization of object knowledge in the brain?

Various forms of category-specificity have been described at both the cognitive and neural levels, inviting the inference that different semantic domains are processed by distinct, dedicated mechanisms. In this paper, we argue for an extension of a domain-specific interpretation to these phenomena that is based on network-level analyses of functional coupling among brain regions. On this view, domain-specificity in one region of the brain emerges because of innate connectivity with a network of regions that also process information about that domain. Recent findings are reviewed that converge with this framework, and a new direction is outlined for understanding the neural principles that shape the organization of conceptual knowledge.     

Sex differences in face processing: Are women less lateralized and faster than men?

The aim of this study was to determine the influence of sex on hemispheric asymmetry and cooperation in a face recognition task. We used a masked priming paradigm in which the prime stimulus was centrally presented; it could be a bisymmetric face or a hemi-face in which facial information was presented in the left or the right visual field and projected to the right or the left hemisphere. The target stimulus was always a bisymmetric face presented centrally. Faces were selected from Minear and Park’s (2004) database. Fifty-two right-handed students (26 men, 26 women) participated in this experiment, in which accuracy (percentage of correct responses) and reaction times (RTs in ms) were measured. Although accuracy data showed that the percentage of correct recognition – when prime and target matched – was equivalent in men and women, men’s RTs were longer than women’s in all conditions. Accuracy and RTs showed that men are more strongly lateralized than women, with right hemispheric dominance. These results suggest that men are as good at face recognition as women, but there are functional differences in the two sexes. The findings are discussed in terms of functional cerebral networks distributed over both hemispheres and of interhemispheric transmission.     

Do top and bottom contribute to object perception more than left and right?

To examine whether the top–bottom axis has an inherent advantage in object perception over the left–right one, three experiments were conducted. In all of them, on each trial one of two alternative stimuli, identical in shape but opposite in direction (viz, related by reflection), was presented. Both reflection about the vertical axis and reflection about the horizontal axis were applied, in different blocks. In Experiment 1, objects with an orientation-free definition (arrows, incomplete squares) were presented. Subjects were to respond when the stimulus pointed in a specific direction, and to refrain from responding when it was reflected, namely pointed in the opposite direction. Axis of reflection (vertical, horizontal) was varied between blocks. In Experiment 2, the object was a Hebrew character asymmetric on both axes, presented either in its normal appearance or reflected. Subjects were to respond only when the stimulus was normal. Both axis of reflection (vertical, horizontal) and orientation angle (upright, tilted by 90°) were varied between blocks. In Experiment 3, stimuli were the same as in Experiment 2, but the task explicitly asked for a binary reflection judgment (normal vs. reflected). No sign for the presence of an axis effect was observed in any of those experiments, which seems incompatible with the hypothesis of vertical advantage in object perception. It is suggested that most vertical advantage observed before is due to extra-perceptual processing.

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How do the internal details of the object contribute to recognition?

Object recognition becomes difficult when the main axis of the object is foreshortened. It has previously been reported that this so-called foreshortened disadvantage is larger when the silhouette of the object is presented than when the line drawing of the object is presented. The pronounced foreshortened disadvantage in silhouette recognition indicates that the internal details of the object, which are absent in the silhouette, provide useful information, particularly when the main axis is foreshortened. But the role of these internal details remains controversial. One account for the pronounced disadvantage is that the internal details contribute to the derivation of the main axis. The other account is that internal details provide the distinctive features that are directly matched to the object represented in memory. The aim in the present study was to determine which of these two explanations best accounts for the differential foreshortened disadvantage between line drawings and silhouettes. To reduce the uncertainty regarding the axis orientation, a 3-D arrow indicating the orientation of the main axis was presented as a cue before the object itself was presented. As a result, the difference in the foreshortened disadvantage between silhouettes and line drawings disappeared. This indicated that the pronounced foreshortened disadvantage for silhouettes was caused by a lack of axis information. In other words, the internal details provided the information necessary for axis derivation when the axis was foreshortened.     

Does the brain's ventral visual pathway compute object shape?

A rich behavioral literature has shown that human object recognition is supported by a representation of shape that is tolerant to variations in an object's appearance. Such 'global' shape representations are achieved by describing objects via the spatial arrangement of their local features, or structure, rather than by the appearance of the features themselves. However, accumulating evidence suggests that the ventral visual pathway – the primary substrate underlying object recognition – may not represent global shape. Instead, ventral representations may be better described as a basis set of local image features. We suggest that this evidence forces a reevaluation of the role of the ventral pathway in object perception and posits a broader network for shape perception that encompasses contributions from the dorsal pathway.     

The boundary conditions for Bohr’s law: when is reacting faster than acting?

In gunfights in Western movies, the hero typically wins, even though the villain draws first. Niels Bohr (Gamow, The great physicists from Galileo to Einstein. Chapter: The law of quantum, 1988) suggested that this reflected a psychophysical law, rather than a dramatic conceit. He hypothesized that reacting is faster than acting. Welchman, Stanley, Schomers, Miall, and Bülthoff (Proceedings of the Royal Society of London B: Biological Sciences, 277, 1667-1674, 2010) provided empirical evidence supporting "Bohr's law," showing that the time to complete simple manual actions was shorter when reacting than when initiating an action. Here we probe the limits of this effect. In three experiments, participants performed a simple manual action, which could either be self-initiated or executed following an external visual trigger. Inter-button time was reliably faster when the action was externally triggered. However, the effect disappeared for the second step in a two-step action. Furthermore, the effect reversed when a choice between two actions had to be made. Reacting is faster than acting, but only for simple, ballistic actions.     

Clergymen and clergywomen: the same inclusive gospel?

Some commentators suggest that clergywomen bring a different perspective to ministry in comparison with that brought by clergymen. This paper explores the extent to which clergywomen bring a more inclusive set of values and beliefs to the pulpit. Data from the Church Times Survey conducted in April 2001 enable this question to be examined across four main areas: inclusive beliefs, pastoral inclusivity, inclusive views on ordained ministry, and social inclusivity. The analysis suggests that clergywomen do bring a more inclusive perspective to ministry than clergymen across the four areas explored in this study.