Perceived arm posture and remote haptic perception of whether an object can be stepped over

The authors investigated whether the perceived posture of the arm plus a hand-held object influences remote haptic perception of whether an object can be stepped over. Blindfolded participants (N = 20) determined whether they could step over bars at different heights by exploring the bars with a T-shaped rod. The rod was weighted so that the perceived posture of the arm-plus-rod was shifted up, down, or left unchanged. Both the leg length of the participant and the perceived posture of the arm-plus-rod systematically influenced perception of whether the bar could be stepped over. The results highlight the role of perceived posture of the arm-plus-rod in remote haptic perception and have potential implications for the design of navigation aids for the visually impaired.     

Inhibition of return to an occluded object depends on expectation

Inhibition of return (IOR) is indexed by slower reaction times to targets presented at previously attended locations or objects. If a moving object is occluded, some studies find IOR, others do not. Four experiments examined whether this inconsistency hinges on the observer's expectation as to whether the object continues to exist at the end of its motion sequence. Results showed that observer expectation is a powerful determining factor: IOR occurs only if the observer expects the object to continue to exist. In contrast, if the object is not occluded, IOR occurs only if the object remains on view immediately before the target is presented. It was concluded that 2 factors, object continuity and observer expectation, mediate both location- and object-based IOR.     

Inhibition of return can be associated with object identity but not with object category

In this study, pre-schoolers and a comparison sample of fifth graders and high school students were presented with prediction tasks that varied by content of the base rate information (perceptual vs semantic) either presented alone (simple task) or accompanied by individuating data (complex task). Base rate choices, confidence scores, and explanations of the choices were registered. It is assumed that the presence of content effects in the processing of the base rates is in favour of a mental model account. Results indicated that pre-schoolers are able to build one-dimensional models with perceptual base rates in simple tasks. Fifth graders and high school students are able to build one-dimensional models with both types of content in simple tasks, as well as two-dimensional models in complex tasks. There is a local facilitation effect of semantic contents for fifth graders that disappears for high-school students. Consistency between subjects' choices, confidence scores and rationales depends on the subjects' grade, the number of sources involved, and the base rate content. Developmental trends are discussed in the light of previous research within formal, heuristic, and mental model approaches.     

Perception of the length of an object through dynamic touch is invariant across changes in the medium

Rotational inertia—a mechanical quantity that describes the differential resistance of an object to angular acceleration in different directions—has been shown to support perception of the properties of that object through dynamic touch (wielding). The goal of the present study was to examine if perception of the length of an object through dynamic touch depends on its rotational inertia, independent of the medium in which it is wielded. The participants (n = 14) wielded 12 different objects held in air or completely immersed in water and reported perceived lengths of those objects. Each object consisted of a rod of a particular density with a particular number of stacked steel rings attached at a particular location along its length. Perceived length was invariant across medium. In addition, a single-valued function of the major eigenvalue, I ₁, and the minor eigenvalue, I ₃, of the rotational inertia, I, of the 12 objects predicted the perceived lengths of those objects in both air and water, and the perceived lengths were invariant across the two media. These results support the hypothesis that the informational support for perception of the length of an object through dynamic touch is invariant across changes in the medium.     

The effects of 'non-directive' questioning on an anticipated decision whether to undergo predictive testing for heart disease: an experimental study

This study investigates how individuals can be helped to make decisions about predictive genetic testing. Participants (n = 120) rated how likely they would be to opt for predictive testing for heart disease if it were available, and other variables such as anxiety about heart disease. They received information on predictive testing for heart disease and ratings were repeated. Participants were then randomly allocated to one of three groups and focused on the personal relevance of positive issues or negative issues which had been mentioned as part of the standardised information previously given. The third group focused on issues irrelevant to testing for heart disease. The form of questioning used in this focusing manipulation was intended to model the processes involved in non-directive questioning. Results showed a significant increase in likelihood of testing in the positive group, and a significant decrease in the negative group. There was also a significant decrease in rated anxiety about heart disease and perceived severity of an increased susceptibility to heart disease of the negative group relative to the positive and control groups. The results may have implications for the ways in which pre-test counselling is carried out.     

Perception of facial expression depends on prior attention

Attending versus ignoring a stimulus can later determine how it will be affectively evaluated. Here, we asked whether attentional states could also modulate subsequent sensitivity to facial expressions of emotion. In a dual-task procedure, participants first rapidly searched for a gender-defined face among two briefly displayed neutral faces. Then a test face with the previously attended or ignored face’s identity was presented, and participants judged whether it was emotionally expressive (happy, angry, or fearful) or neutral. Intensity of expression in the test face was varied so that an expression detection threshold could be determined. When fearful or angry expressions were judged, expression sensitivity was worse for faces bearing the same identity as a previously ignored versus attended face. When happy expressions were judged, sensitivity was unaffected by prior attention. These data support the notion that the motivational value of stimuli may be reduced by processes associated with selective ignoring.     

Priming on perceptual implicit memory tests can be achieved through presentation of associates

Roediger and McDermott (1995) presented lists of semantic associates (e.g.,door, glass, pane, shade, ledge) to induce false recall of related, nonpresented words (e.g.,window). This study procedure was used in an attempt to determine whether associative activation of target words would be sufficient to produce priming on perceptual implicit memory tests. Priming of the nonpresented items occurred on both word stem completion and word fragment completion, but the level of priming was generally lower than for items that had been studied. Priming of the related, nonpresented words occurred on a conceptual implicit test of word association; further, the level of priming was equivalent to that of presented words.     

Perception and understanding of effects of gravity and inertia on object motion

Experiments using a preferential looking method, a perceptual judgment method, and a predictive judgment method investigated the development, from 7 months to 6 years of age, of sensitivity to the effects of gravity and inertia on inanimate object motion. The experiments focused on a situation in which a ball rolled off a flat surface and either continued in linear motion (contrary to gravity), turned abruptly and moved downward (contrary to inertia), or underwent natural, parabolic motion. When children viewed the three fully visible motions, both the preferential looking method and the perceptual judgment method provided evidence that sensitivity to inertia developed between 7 months and 2 years, and that sensitivity to gravity began to develop after 3 years. When children predicted the future location of the object without viewing the motions, the predictive judgment method provided evidence that sensitivity to gravity had developed by 2 years, whereas sensitivity to inertia began to develop only at 5–6 years. These findings suggest that knowledge of object motion develops slowly over childhood, in a piecemeal fashion. Moreover, the same system of knowledge appears to be tapped both in preferential looking tasks and in judgment tasks when children view fully visible events, but a different system may underlie children’s inferences about unseen object motions.     

The direction of hemispheric asymmetries for object categorization at different levels of abstraction depends on the task

In this study hemispheric asymmetries for categorizing objects at the basic versus subordinate level of abstraction were investigated. As predictions derived from different theoretical approaches are contradictory and experimental evidence is inconclusive in this regard, we conducted two categorization experiments, where we contrasted two experimental paradigms. In the first experiment, subjects had to verify whether a word and a laterally presented picture matched or not. In the second experiment, subjects had to identify laterally presented pictures of animals either at the basic or subordinate level by pressing a corresponding response key. Whereas the first experiment revealed an advantage of the left hemisphere (LH) for categorizing objects at the basic level and of the right hemisphere (RH) for categorizing at the subordinate level, just the opposite brain asymmetry was found in the second experiment. As the stimuli were identical in both experiments, hemispheric asymmetries seem to be strongly task dependent.     

Influence of perturbation induced by an anticipated load on human motor regulatory systems.

To investigate how human motor regulatory systems are modified by prior knowledge of a predictable external perturbation, six normal human subjects, each when sitting on a chair, were required to maintain a stable elbow flexion angle (90 degrees) while different weight perturbations were applied (0.5 kg or 2-kg loads). Loads were applied either by the experimenter Without Anticipation or With Anticipation by the subject's own contralateral hand. Acceleration of the forearm movement (elbow extension and flexion) by loads and electromyograms (EMGs) of the biceps brachii (BB) and the triceps brachii (TB) muscle were recorded. Under With Anticipation conditions, preceding EMG activities of BB and TB muscles prior to the onset time of perturbation were clearly observed. Furthermore, the amount of these preceding EMG activities was larger in the heavy load perturbation than in the light load perturbation. Under Without Anticipation conditions, however, these preceding EMG activities were not observed. In the preceding EMG activities, EMG bursts (latency 20 msec.) of a presumed stretch reflex induced by the perturbation were clearly observed. Thus, the function of anticipatory adjustment of mainitaining the elbow angle definitely appears to optimize limb stability in the case of the mechanical self-applied perturbation. Furthermore, the extent of the anticipatory adjustment of the elbow angle was dependent on the predicted magnitude of load.     

Re-construction of action awareness depends on an internal model of action-outcome timing

The subjective time of an instrumental action is shifted towards its outcome. This temporal binding effect is partially retrospective, i.e., occurs upon outcome perception. Retrospective binding is thought to reflect post-hoc inference on agency based on sensory evidence of the action – outcome association. However, many previous binding paradigms cannot exclude the possibility that retrospective binding results from bottom-up interference of sensory outcome processing with action awareness and is functionally unrelated to the processing of the action – outcome association. Here, we keep bottom-up interference constant and use a contextual manipulation instead. We demonstrate a shift of subjective action time by its outcome in a context of variable outcome timing. Crucially, this shift is absent when there is no such variability. Thus, retrospective action binding reflects a context-dependent, model-based phenomenon. Such top-down re-construction of action awareness seems to bias agency attribution when outcome predictability is low.     

The effect of performance trend on performance ratings occurs through observer attributions,but depends on performance variability

Research regarding the influence of dynamic performance characteristics on performance ratings suggests that raters are remarkably susceptible to observed trends in performance over time, such that systematic trends or patterns in performance can have an undue influence on how performance is evaluated. However, research in this domain has not fully explained how dynamic performance characteristics influence performance judgments. Drawing on attribution theory, we introduce a model whereby the impact of dynamic performance characteristics on subsequent performance judgments occurs through attributions for performance. Then, in three experimental studies, we show that dynamic performance characteristics influence attributions for performance, which in turn affect performance ratings.     

‘Unconscious transference’ can be an instance of ‘change blindness’

Three experiments investigated the role of ‘change blindness’ in mistaken eyewitness identifications of innocent bystanders to a simulated crime. Two innocent people appeared briefly in a filmed scene in a supermarket. The ‘continuous innocent’ (CI) walked down the liquor aisle and passed behind a stack of boxes, whereupon the perpetrator emerged and stole a bottle of liquor, thereby resulting in an action sequence promoting the illusion of continuity between perpetrator and innocent. The ‘discontinuous innocent’ (DI) was shown immediately afterward in the produce aisle. Results revealed that: (1) more than half of participants failed to notice the change between the CI and the perpetrator, (2) among those who failed to notice the change, more misidentified the ‘CI’ than the ‘DI’, a pattern that did not hold for those who did notice the change. Participants were less likely to notice the change when they were distracted while watching the video. Copyright © 2007 John Wiley & Sons, Ltd.     

Influence of numerical magnitudes on the free choice of an object position

The link between numerical magnitude and mechanisms of spatial orienting has been underlined in an increasing number of studies. Similarly, the relationship between numerical magnitude and grasping actions has started to be investigated. The present study focuses on the influence of numerical magnitude processing in the free choice of the position of an object. Participants were presented with a digit (1-9 without 5) and were required to decide whether it was smaller or larger than 5. Then, they had to grasp a small cube and change its position before vocally responding "higher" or "lower". Results showed that in the initial phase of the grasp movement, the grip aperture was modulated by the numerical magnitude. Moreover, participants shifted the position of the cube more leftward with smaller digits compared with larger ones, and they tended to position the object closer to themselves with smaller digits compared with larger ones. These results extend the previous findings indicating that the processing of magnitude is tightly related to the mechanisms of spatial orienting that subserve action execution.     

Effects of head orientation on gaze perception: how positive congruency effects can be reversed

Several past studies have considered how perceived head orientation may be combined with perceived gaze direction in judging where someone else is attending. In three experiments we tested the impact of different sources of information by examining the role of head orientation in gaze-direction judgements when presenting: (a) the whole face; (b) the face with the nose masked; (c) just the eye region, removing all other head-orientation cues apart from some visible part of the nose; or (d) just the eyes, with all parts of the nose masked and no head orientation cues present other than those within the eyes themselves. We also varied time pressure on gaze direction judgements. The results showed that gaze judgements were not solely driven by the eye region. Gaze perception can also be affected by parts of the head and face, but in a manner that depends on the time constraints for gaze direction judgements. While “positive” congruency effects were found with time pressure (i.e., faster left/right judgements of seen gaze when the seen head deviated towards the same side as that gaze), the opposite applied without time pressure.     

Effects of head orientation on gaze perception: How positive congruency effects can be reversed

Several past studies have considered how perceived head orientation may be combined with perceived gaze direction in judging where someone else is attending. In three experiments we tested the impact of different sources of information by examining the role of head orientation in gaze-direction judgements when presenting: (a) the whole face; (b) the face with the nose masked; (c) just the eye region, removing all other head-orientation cues apart from some visible part of the nose; or (d) just the eyes, with all parts of the nose masked and no head orientation cues present other than those within the eyes themselves. We also varied time pressure on gaze direction judgements. The results showed that gaze judgements were not solely driven by the eye region. Gaze perception can also be affected by parts of the head and face, but in a manner that depends on the time constraints for gaze direction judgements. While “positive” congruency effects were found with time pressure (i.e., faster left/right judgements of seen gaze when the seen head deviated towards the same side as that gaze), the opposite applied without time pressure.