Background surface and horizon effects in the perception of relative size and distance

The projected height of an object in a scene relative to a ground surface influences its perceived size and distance, but the effect of height should change when the object is moved above the horizon. In four experiments, observers judged relative size or relative distance for pairs of objects varying in height with respect to the horizon. Higher objects equal in projected size were judged larger below the horizon, but the relative size effect was reversed either when one object was on the horizon and one was above the horizon or when both objects were above the horizon. With the real horizon not explicitly present in the display, relative size judgements were affected both by the boundary of the visible surface and the vanishing point implied by the converging lines. For relative distance judgements, the higher object was judged more distant regardless of the height of the objects relative to the perceptual horizon, resulting in a reversal of the relation between size and distance judgements for objects above the horizon.     

Young children's coordination of motive and outcome in judgements of satisfaction and morality

Three- to seven-year-old children judged a story-character's satisfaction. Their comprehension of the relationship between motives and outcomes of action was tested by presenting them with matching and with mismatching outcomes. For example, one character's motive, depicted in a ‘thinks’ bubble, was to throw a ball to one of two children. In a matching outcome, the intended child caught the ball, whereas in a mismatching outcome, the other child caught it. Even the youngest children judged the character more pleased when the outcome matched his motive than when it did not. This suggests that children from three years old can integrate motive and outcome information. Children under seven years failed to judge satisfaction appropriately when motives and outcomes were bad. Comparisons of children's satisfaction judgements with their moral judgements of the story-characters suggested possible reasons for this failure. The implications of the results for social cognition and information integration are discussed.     

Auditory-visual interactions in the perception of a ball's path

We carried out two experiments to measure the combined perceptual effect of visual and auditory information on the perception of a moving object's trajectory. All visual stimuli consisted of a perspective rendering of a ball moving in a three-dimensional box. Each video was paired with one of three sound conditions: silence, the sound of a ball rolling, or the sound of a ball hitting the ground. We found that the sound condition influenced whether observers were more likely to perceive the ball as rolling back in depth on the floor of the box or jumping in the frontal plane. In a second experiment we found further evidence that the reported shift in path perception reflects perceptual experience rather than a deliberate decision process. Instead of directly judging the ball's path, observers judged the ball's speed. Speed is an indirect measure of the perceived path because, as a result of the geometry of the box and the viewing angle, a rolling ball would travel a greater distance than a jumping ball in the same time interval. Observers did judge a ball paired with a rolling sound as faster than a ball paired with a jumping sound. This auditory-visual interaction provides an example of a unitary percept arising from multisensory input.     

Relations between subjective evaluations of memory and objective memory performance.

Several explanations for the weak relations between subjective memory judgements and objective memory performance were investigated in two groups of normal older adults. Group 1 sampled a general population (mean age 61.6 yr., range 46-89), while Group 2 sampled subjects who were on a waiting list for memory training (mean age 63.0 yr., range 45-85 years). In both groups, subjective memory judgments were assessed with global ratings of memory capacity and with ratings of frequency of forgetting in specific memory situations. Memory performance was assessed with several well-known tests and with recently developed tests for domain-specific aspects of memory. Most tests concerned episodic memory. Study 1 also included measures of semantic, incidental and working memory. Study 2 further examined the influence of the domain-specificity of objective and subjective measures for remembering names, intentions, and texts. Relations between memory self-reports and performance were weak in both groups and for all kinds of tests. Against expectations, the low correlations could not be explained by differences between ecological and laboratory tests or incidentally and intentionally remembered information, or by differences between specific failures compared to global, stereotyped judgments. Surprisingly, correlations did not increase when subjective and objective measures assessed the same ability, like remembering names. Also noncognitive variables (mood and lifestyle) did not influence the relations. The (weak) relations between subjective and objective memory measures were comparable for subjects over and under 65 years of age. Furthermore, relations were comparable for the general population sample and the memory compliant group.     

Toward a unified fielder theory: what we do not yet know about how people run to catch a ball.

Linear optic trajectory theory claims that people catch balls by running in a direction that keeps an optic trajectory of the ball linear. The authors show a range of ball trajectories for which departures of the optic trajectory from linearity do not predict which direction people will run, and the direction they choose does not correct these departures. Data from a wide range of ball trajectories show that people run so that the angle of elevation of gaze to the ball increases at a decreasing rate. But it is not yet known why people choose the particular path they do from the many that would achieve this.     

Rate of change of angular bearing as the relevant property in a horizontal interception task during locomotion

The authors ran 3 experiments to investigate how catchers deal with the horizontal component of the ball's trajectory in an interception task during locomotion. The experiments were built upon the finding that velocity adaptations are based upon changes in the horizontal angular position or velocity of the ball with respect to the observer (M. Lenoir, M. Janssens, E. Musch, E. Thiery, J. Uyttenhove, 1999) a potential underlying information source for that strategy is described. In Experiment 1, actor (N = 10 participants)and ball approached each other along the legs of a V-shaped track. When the velocity and the initial angular bearing of the ball were varied, the observed behavior fitted with nulling the horizontal angular velocity of the ball: A positive or negative angular velocity was compensated by a velocity change. Evidence was obtained that those adaptations are modulated by a critical change in, rather than by a critical state of, the environment-actor system. In Experiment 2, the distance between the head and an artificial end-effector was varied. Irrespective of that distance, participants (N = 7) accelerated and decelerated in order to keep the angular velocity of the ball with respect to the end-effector close to constant. The ecological relevance of that constant bearing angle strategy was confirmed in Experiment 3: Participants (N = 7) in that experiment freely ran to catch fly balls. The present results support the concept that one can explain with a limited number of control variables an actor's behavior in an interception task during self-motion.     

Measuring the size of mental images

Mental images seem to have a size; the experimental problem was to map that image size onto a scale of physical measurement. To this end, two experiments were conducted to measure the size of mental images in degrees of visual angle. In Experiment 1, college students employed light pointers to indicate the horizontal extent of projected mental images of words (the letter string, not the referent). Imagined words covered about 1.0 degress of visual angle per letter. In Experiment 2, a more objective eye-movement response was used to measure the visual angle size of imagined letter strings. Visual angle of eye movement was found to increase regularly as the letter distance between the fixation point and a probed letter position increased. Each letter occupied about 2.5 degrees of visual angle for the four-letter strings in the control/default size condition. Possible relations between eye movements and images are discussed.     

Evidence for a distinction between judged and perceived causality

Two experiments investigated Michotte's launch event, in which successive motion of two objects appears to evoke an immediate perception that the first motion caused the second, as in a collision. Launching was embedded in event sequences where a third event (a colour change of the second object) was established as a competing predictor of the second motion, in an attempt to see whether subjects' learning of alternative predictive relationships would influence their causal impressions of launch events. In Experiment 1 subjects saw launch events in which temporal contiguity at the point of impact was varied so that an impact was varied so that an impact itself did not reliably predict when the second object would move. Half of these scenes, however, contained a colour change of the second object which did reliably predict when it would move. In accordance with Michotte's theory, subjects' ratings of the degree of perceived causality were not affected by the colour change. In Experiment 2 subjects saw scenes that contained launch events with or without temporal contiguity and a colour change. These were interspersed with events in which a colour change alone did or did not precede the second motion. Thus, movement of the second object was either contingent on or independent of the impact. Subjects repeatedly (a) rated perceived causality in single launch events and (b) judged the necessity of collisions for movement in the overall set of events. These responses dissociated, in that ratings type (a) showed only a substantial contiguity effect, whereas judgements of type (b) showed both a contingency and a much smaller contiguity effect. These results appear to support a distinction between judged and perceived causality and are discussed with respect to Michotte's theory of direct causal perception.     

Embodied information affects judgements about politicians: The impact of haptic weight sensations and hand cleansing

Politicians' characteristics attract voters' attention and dominate impression formation. Thereby, social judgements are deduced from different information being available in a certain situation. The literature suggests that incidental bodily sensations can influence judgement processes. Here, two bodily treatments—the haptic sensation of weight and the act of hand cleansing—simultaneously contribute to judgements about politicians. This study expands previous works by (a) investigating potential interactions of two haptic information cues, (b) providing evidence for the significant role of conceptual closeness between embodied cues and judgement dimensions, (c) showing that hand cleansing leads to harsher moral judgements independently of whether a misconduct has been committed or not, and (d) showing that the familiarity of the target to be judged does not moderate the effect of embodied information. The results demonstrate that judgements can be modulated by basal sensorimotor experiences. We discuss implications and the important issue of result generalisation and replicability.     

Bouncing between model and data: stability, passivity, and optimality in hybrid dynamics

Rhythmically bouncing a ball with a racket is a seemingly simple task, but it poses all the challenges critical for coordinative behavior: perceiving the ball's trajectory to adapt position and velocity of the racket for the next ball contact. To gain insight into the underlying control strategies, the authors conducted a series of studies that tested models with experimental data, with an emphasis on deriving model-based hypotheses and trying to falsify them. Starting with a simple dynamical model of the racket and ball interactions, stability analyses showed that open-loop dynamics affords dynamical stability, such that small perturbations do not require corrections. To obtain this passive stability, the ball has to be impacted with negative acceleration--a strategy that subjects adopted in a variety of conditions at steady state. However, experimental tests that applied perturbations revealed that after perturbations, subjects applied active perceptually guided corrections to reestablish steady state faster than by relying on the passive model's relaxation alone. Hence, the authors derived a model with active control based on optimality principles that considered each impact as a separate reaching-like movement. This model captured some additional features of the racket trajectory but failed to predict more fine-grained aspects of performance. The authors proceed to present a new model that accounts not only for fine-grained behavior but also reconciles passive and active control approaches with new predictions that will be put to test in the next set of experiments.     

Launching at a distance: The effect of spatial markers

It has been widely reported that spatial contiguity is important to judgements of causality involving one object launching another [Michotte's “launching effect” (1963, 1991)]. The present study examined the impact of different types of spatial markers on causal judgements of a distal launch (one object approaching other, stopping short of it, and the second object subsequently moving along the same trajectory). The spatial markers were objects that either partially or completely bridged the spatial gap between two objects (Experiment 1), or they were dashed lines that marked the stopping location of the first object or the starting location of the second object (Experiment 2). The presence of either objects or dashed lines could produce higher causal ratings, but the location of the marker mattered. The results suggest that altering a cause's ability to predict when the effect would occur (via a spatial marker) and the presence of a conduit for energy transmission have independent effects on causal judgements of object interaction.     

The time it takes to make veridical size and distance judgments

Two experiments measuring the time it takes to make veridical size judgments under normal (unreduced) conditions of viewing showed that RT tended to increase with increases in viewing distance between 122 and 305 cm, even for targets subtending the same visual angle at all distances. Two experiments measuring the time it takes to judge distance under the same conditions did not reveal any difference in RT as a function of the extent-of-distance judged. Established accounts of size perception do not suggest an explanation of these findings.     

Causal judgement from contingency information: Judging interactions between two causal candidates

In two experiments participants judged the extent to which occurrences and non-occurrences of an effect could be attributed to an interaction between two causal candidates A and B. In Experiment 1 judgements were influenced by the proportion of instances normatively evaluated as confirmatory for the interaction interpretation, when the objective contingency was held constant. Information about instances in which both candidates were present and the effect occurred was more influential than information about instances in which both candidates were absent and the effect did not occur. In Experiment 2 the occurrence rate of the effect when both candidates were present, when A alone was present, when B alone was present, and when both were absent was manipulated. Interaction judgements were mainly determined by occurrence rate when both were present. There was also a significant effect of occurrence rate when both were absent, but the other two occurrence rates had no significant effect. These results are interpreted as supporting a general model in which causal judgements are made according to the proportion of instances evaluated as supporting the interpretation being judged.     

Auditory perception of relative distance of traffic sounds

This study examines the accuracy of judgements of relative distance of traffic sounds (car and lorry) compared with nonattributed sounds (white noise). Adults judged whether sounds were comparatively nearer or further away in both conditions when decibel levels were the same and when decibel levels differed. Results indicated that judgement of relative distance is generally difficult and that such judgements are not based on loudness alone, particularly for traffic sounds. More errors were made when decibel levels were the same, indicating a reluctance to rely on loudness as an indicator of distance. Also more errors were made for traffic sounds. It was suggested that nonauditory criteria may be used in interpreting sounds, possibly including past experience and visual imagery. Finally, the implications of the results for road safety are discussed.     

Auditory perception of relative distance of traffic sounds

This study examines the accuracy of judgements of relative distance of traffic sounds (car and lorry) compared with nonattributed sounds (white noise). Adults judged whether sounds were comparatively nearer or further away in both conditions when decibel levels were the same and when decibel levels differed. Results indicated that judgement of relative distance is generally difficult and that such judgements are not based on loudness alone, particularly for traffic sounds. More errors were made when decibel levels were the same, indicating a reluctance to rely on loudness as an indicator of distance. Also more errors were made for traffic sounds. It was suggested that nonauditory criteria may be used in interpreting sounds, possibly including past experience and visual imagery. Finally, the implications of the results for road safety are discussed.     

The effects of angle-arm length on judgments of angle magnitude and orientation contrast

Acute angles frequently are overestimated, an effect that has been attributed to lateral inhibitory mechanisms. It can be derived from such theories that lengthening the arms of an angle should either reduce or not affect its judged subtense. However, in Experiments 1 and 2, it was found that angles with longer arms were judged larger. In Experiment 3, direct measures of anglearm orientation indicated that orientation contrast does not increase with angle-arm length, that it decreases with distance from the angle vertex, and that these effects are not averaged along the entire length of the arm. It follows that inhibitory mechanisms alone cannot explain why longer armed angles appear larger or why angle arms appear straight rather than bowed. It is suggested that a distinction is required between the orientation and the angular domains and that the latter judgments depend, at least partially, on the space or area within an angle. The fact that angles appear unbowed may reflect the fact that perceived orientation differences occur along an angle’s arm only when matches are made to small segments of the arm.     

Rate of Change of Angular Bearing as the Relevant Property in a Horizontal Interception Task During Locomotion

The authors ran 3 experiments to investigate how catchers deal with the horizontal component of the ball's trajectory in an interception task during locomotion. The experiments were built upon the finding that velocity adaptations are based upon changes in the horizontal angular position or velocity of the ball with respect to the observer (M. Lenoir, M. Janssens, E. Musch, E. Thiery, & J. Uyttenhove, 1999); a potential underlying information source for that strategy is described. In Experiment 1, actor (N = 10 participants) and ball approached each other along the legs of a V-shaped track. When the velocity and the initial angular bearing of the ball were varied, the observed behavior fitted with nulling the horizontal angular velocity of the ball: A positive or negative angular velocity was compensated by a velocity change. Evidence was obtained that those adaptations are modulated by a critical change in, rather than by a critical state of, the environment-actor system. In Experiment 2, the distance between the head and an artificial end-effector was varied. Irrespective of that distance, participants (N = 7) accelerated and decelerated in order to keep the angular velocity of the ball with respect to the end-effector close to constant. The ecological relevance of that constant bearing angle strategy was confirmed in Experiment 3: Participants (N = 7) in that experiment freely ran to catch fly balls. The present results support the concept that one can explain with a limited number of control variables an actor's behavior in an interception task during self-motion.     

Surface lightness influences perceived room height

Surprisingly little scientific research has been conducted on the effects of colour and lightness on the perception of spaciousness. Practitioners and architects typically suggest that a room's ceiling appears higher when it is painted lighter than the walls, while darker ceilings appear lower. Employing a virtual reality setting, we studied the effects of the lightness of different room surfaces on perceived height in two psychophysical experiments. Observers judged the height of rooms varying in physical height as well as in the lightness of ceiling, floor, and walls. Experiment 1 showed the expected increase of perceived height with increases in ceiling lightness. Unexpectedly, the perceived height additionally increased with wall lightness, and the effects of wall lightness and ceiling lightness were roughly additive, incompatible with a simple effect of the lightness contrast between the ceiling and the walls. Experiment 2 demonstrated that the floor lightness has no significant effect on perceived height, and that the total brightness of the room is not the critical factor influencing the perceived height. Neither can the results be explained by previously reported effects of brightness on apparent depth or perceived distance.     

ON THE RELATIONSHIP BETWEEN PHENOMENAL SPACE AND PHENOMENAL VELOCITY

The hypothesis that changing the phenomenal distance traversed by a moving spot, while keeping the physical distance constant, should affect the phenomenal velocity in a like direction was tested by having the stimulus motion path bounded by Müller-Lyer figures. It was found that while these affected motion path length judgements in the same direction as static length judgements, they did not have a corresponding effect on velocity judgements. The Müller-Lyer figure producing a decreased length judgement was actually found to increase velocity judgements. Two possible explanations of this result were tested and the conclusion drawn that this increase could be due to the enclosing nature of the Müller-Lyer figure in question.     

Influences of familiarity on the processing of faces

Three experiments are reported in which undergraduate subjects made simple perceptual judgements about the faces of familiar and unfamiliar academic staff. Any effects of familiarity in these tasks were assessed by comparison with performance on the two groups of faces when both sets were unfamiliar to student subjects at a different university. In experiment 1 there was no effect of familiarity of the faces on a task requiring judgements of expression, consistent with recent models of face processing in which expression analysis proceeds independently from the analysis of identity. In experiment 2 there was a significant effect of familiarity on a task in which the sex of the faces was judged. This appeared to be due to familiarity acting to facilitate only those faces whose sex was difficult to judge from the picture presented. In experiment 3, significant effects of familiarity were also observed when the task was to distinguish intact faces from jumbled faces. Although the effects of familiarity in experiments 2 and 3 were small and emerged in interactions between item sets and university, they suggest that a simple perceptual hierarchy of the kind proposed by Ellis requires some revision.