Judgments of differences and ratios of subjective heaviness

Attention, Perception, & Psychophysics - Experimental instructions to judge differences or ratios of subjective heaviness numerically are generally assumed to produce judgments linearly...     

Differences in heaviness in relation to density and weight

Eight Ss (Group L) judged differences in heaviness between all pairs of stimuli in three series of five weights each, in the range of 100–300 g, presented randomly. Series L varied in weight and density, Series LVW varied only in weight, and Series LVD varied only in density. Another eight Ss (Group H) judged heaviness differences between all pairs of stimuli in three similar series (H, HVW, and HVD) in the range 700–900 g. Differences in density alone yielded relatively greater impressions of difference in heaviness in Group H than in Group L. Predictions from Ross and Di Lollo’s vector theory were confirmed.     

Rotational kinematics influence multimodal perception of heaviness

Perceived heaviness has been shown to be specific to an object’s rotational inertia (I ), its resistance to rotational acceleration. According to the kinematic specification of dynamics (KSD) principle, we hypothesized that I is optically specified by rotational kinematics. Using virtual depictions of wielded objects, we investigated whether the visually detected rotational kinematics of wielded objects would influence perceived heaviness in a manner consistent with the inertial model of heaviness perception. We scaled the virtual object’s movement so that it rotated more or less than its wielded counterpart, specifying lower and higher I, respectively. Perceived heaviness was inversely related to the rotational scaling factor, consistent with a KSD interpretation of the inertial model.     

Coming to grips with weight perception: effects of grasp configuration on perceived heaviness

We investigated how changes in grasp configuration affect perceived heaviness in a weight discrimination task in which participants compared the weights of a series of test objects with the weight of a reference object. In different experiments, we varied the width of the grasp, the number of digits employed, the angle of the grasp surface, and the size of the contact area between the digits and the object. We show that objects are perceived to be lighter when lifting with (1) a wide grip in comparison with a narrow grip, (2) five digits in comparison with two digits, and (3) a large contact area in comparison with a small contact area. However, the angle of the contact surfaces did not influence perceived weight. We suggest that changes in central motor commands associated with grasp differences may influence perceived weight, at least under some conditions.     

The dimensionality of judgments of heaviness

Two groups of Ss judged differences in heaviness between all pairs of stimuli in three series of five weights each. One group judged differences in the 100-300 g range, the other group judged differences in the 700–900 g range. The three series of weights in the two ranges consisted of one series of constant size varying in both weight and density, one series varying only in weight, and one series varying only in density. Multidimensional scaling analysis revealed at least two dimensions, and indicated that where both weight and density are allowed to vary, both will affect judgment of the magnitude of differences in heaviness. With heavier weights, density appears to exert an increasingly important influence on judgments of heaviness. Predictions from Ross and Di Lollo’s vector theory were confirmed.     

The relation between size and apparent heaviness

Attention, Perception, & Psychophysics - A formula for the size-weight illusion was derived from the Stevens and Rubin (1970) finding that heaviness functions form a family of power functions...     

The harmful and beneficial impacts of weight bias on well-being: the moderating influence of weight status

Weight bias is evident among normal weight and obese individuals. This weight bias may be associated with comparisons to others, which may enhance feelings of self-worth. However, the ego-enhancing versus ego-diminishing influence of these evaluations may be moderated by the individual's weight status, and the strength of these effects may be moderated by gender. Eight-five participants completed the Implicit Associations Test, questionnaires assessing explicit weight bias, body image, and self-esteem, and height and weight assessments. Implicit weight bias was prevalent among all individuals, p < .001, and was associated with a more positive body image, ps < .05, and higher self-esteem, ps < .01, for thinner individuals but a more negative body image and lower self-esteem for heavier individuals. Gender moderation effects were not observed. It is arguably problematic that the positive benefits to normal weight individuals’ self-esteem and body image appear to come via negative comparisons with overweight individuals.     

The interaction of objective and subjective organizations in a localization search task

We investigated how both objective and subjective organizations affect perceptual organization and how this perceptual organization, in turn, influences observers’ performance in a localization search task. Two groups of observers viewing exactly the same stimuli (objective organization) performed in significantly different ways, depending on how they were induced to parse the display (subjective organization). In Experiments 1 and 2, the observers were asked to describe the location of a tilted target among a varying number of vertical or horizontal distractors. Subjective organization was induced by instructing observers to parse the display into either three horizontal regions (rows) or three vertical regions (columns). The position of the target was critical: location performance, as assessed by reaction time and errors, was consistently impaired at the locations adjacent to the boundaries defining the regions, producing what we refer to as thesubjective boundary effect. Furthermore, the extent of this effect depended on whether the stimulus-driven and conceptually driven information concurred or conflicted. This made location information more or less accessible. In Experiment 1, the strength of objective grouping was a function of the proximity of the items (near or far conditions) and their orientation in a 6×6 matrix. In Experiment 2, the strength of objective grouping was a function of similarity of color (items were color coded by rows or by columns) and the orientation of the items in a 9×9 matrix. The subjective boundary effect was more pronounced when the display promoted grouping in the direction orthogonal to that of the task (e.g., when observers parsed by rows but vertical distractors were closer together [Experiment 1] or color coded [Experiment 2] to induce global columns). In contrast, this effect decreased when the direction of both objective and subjective organizations was parallel (e.g., when observers parsed by rows and horizontal distractors were closer together [Experiment 1] or were color coded [Experiment 2] to induce global rows). A localization search task proved to be an ideal forum in which objective and subjective organizations interacted. We discuss how these results indicated that observers’ performance in a localization task was determined by the interaction of objective and subjective organizations, and that the resulting perceptual organization constrained coarse location information.     

Psychophysical scales of apparent heaviness and the size-weight illusion

The apparent heaviness of a set of 40 cylindrical objects was scaled by the method of magnitude estimation. The objects varied in weight, volume. and density. There were three main conclusions: (1) For any constant volume, heaviness grows as a power function of weight; the larger the volume. the larger the exponent of the power function. The family of such power functions converge at a common point in the vicinity of the heaviest weight that can be lifted. (2) For any constant density (i:e., weight proportional to volume), heaviness does not grow as a power function of weight. (3) For any constant weight, heaviness decreases approximately as a logarithmic function of volume; the constants of the log function depend systematically on the weight of the object. The outcome furnishes a broad quantitative picture of apparent heaviness and of the size-weight illusion (Charpentier’s illusion).     

The surface-weight illusion: on the contribution of grip force to perceived heaviness

Previous psychophysical studies have shown that an object, lifted with a precision grip, is perceived as being heavier when its surface is smooth than when it is rough. Three experiments were conducted to assess whether this surface-weight illusion increases with object weight, as a simple fusion model suggests. Experiment 1 verified that grip force increases more steeply with object weight for smooth objects than for rough ones. In Experiment 2, subjects rated the weight of smooth and rough objects. Smooth objects were judged to be heavier than rough ones; however, this effect did not increase with object weight. Experiment 3 employed a different psychophysical method and replicated this additive effect, which argues strongly against the simple fusion model. The whole pattern of results is consistent with a weighted fusion model in which the sensation of grip force contributes only partially to the perceived heaviness of a lifted object.     

Metamers in the haptic perception of heaviness and moveableness

It is hypothesized that heaviness perception for a freely wielded nonvisible object can be mapped to a point in a three-dimensional heaviness space. The three dimensions are mass, the volume of the inertia ellipsoid, and the symmetry of the inertia ellipsoid. Within this space, particular combinations yield heaviness metamers (objects of different mass that feel equally heavy), whereas other combinations yield analogues to the size-weight illusion (objects of the same mass that feel unequally heavy). Evidence for the two types of combinations was provided by experiments in which participants wielded occluded hand-held objects and estimated the heaviness of the objects relative to a standard. Further experiments with similar procedures showed that metamers of heaviness were metamers of moveableness but not metamers of length. A promising conjecture is that the haptic perceptual system maps the combination of an object's inertia for translation and inertia for rotation to a perception of the object's maneuverability.     

The influence of subjective life expectancy on retirement transition and planning: A longitudinal study

This study examines the construct of subjective life expectancy (SLE), or the estimation of one's probable age of death. Drawing on the tenets of socioemotional selectivity theory (Carstensen, Isaacowitz, & Charles, 1999), we propose that SLE provides individuals with their own unique mental model of remaining time that is likely to affect their retirement planning and decision making. Longitudinal data from 1908 participants showed that SLE measured at Time 1 predicted mature-aged workers' intended retirement age and the extent that they were engaged in retirement preparation 12 months later at Time 2. Furthermore, a shorter SLE at Time 1 increased the odds of actual retirement by Time 2 after controlling for a set of known predictors of retirement. In contrast, a longer SLE at Time 1 increased the odds that a Time 1 retiree had returned to paid work by Time 2. The discussion highlights ways in which SLE can inform financial and vocational counselling for late career decision-makers.     

Seeing and feeling volumes: The influence of shape on volume perception

The volume of common objects can be perceived visually, haptically or by a combination of both senses. The present study shows large effects of the object's shape on volume perception within all these modalities, with an average bias of 36%. In all conditions, the volume of a tetrahedron was overestimated compared to that of a cube or a sphere, and the volume of a cube was overestimated compared to that of a sphere. Additional analyses revealed that the biases could be explained by the dependence of the volume judgment on different geometric properties. During visual volume perception, the strategies depended on the objects that were compared and they were also subject-dependent. However, analysis of the haptic and bimodal data showed more consistent results and revealed that surface area of the stimuli influenced haptic as well as bimodal volume perception. This suggests that bimodal volume perception is more influenced by haptic input than by visual information.     

The influence of diverse interaction contexts on students' sociometric status

Despite there being numerous studies on sociometric status, research that analyzes this variable from a contextualized viewpoint taking into account the different school settings in which a pupil establishes relationships is rare. The aim of this study is to analyze the stability of sociometric status in different school settings. For this purpose, 522 students filled in a sociometric questionnaire that investigated two different settings: the academic setting, which refers to the formal classroom setting; and the leisure setting, which investigates a more informal and playful setting like the playground. The main results indicate that identification percentages are almost the same in both settings. Nonetheless, all sociometric types are contextually dependent, and some are more dependent than others. Thus, rejection is observed as being the most independent of context, whereas the most dependent is that of controversial pupils. Differential analyses show that sex modifies the results obtained. It is shown that, excluding a few exceptions, combinations of sociometric types in both settings investigated can be made. These results are discussed in connection with the methodology used to identify sociometric types and their practical implication for better school adjustment.     

The influence of gender and temperament on children's interaction with a baby

This study examined gender differences in children's interaction with a baby who visited their day-care center over several weeks. Twenty-two children ranging in age from 47 to 64 months of age participated. The children's teacher filled out a questionnaire assessing each child's extraversion, activity level, and loudness. A female baby visited the day care center from one to three times a week over a two-month period. Each child's interactions with the baby were observed twice. Active, outgoing, loud girls were much more likely to interact with the baby than either quiet girls or any boys. Several of these highly interactive girls had no younger siblings. Children were found to interact with the baby more on their second observation.The research reported here was supported by a grant from the Purdue Research Foundation. I would like to thank Connie Clauss for her help with data collection.     

Sensation weighting in comparison and discrimination of heaviness

Participants lifted pairs of successively presented weights and compared them for heaviness, using the constant method with 2, 3, or 6 judgment categories. The standard weight (St) was 100, 200, or 300 g, either roving or fixed within a block. For each St, there were 5 comparison (Co) weights. The lifting orders were St-Co and, with 6 categories, Co-St. Time-order errors were negatively related to St magnitude, particularly with roving St. In terms of Hellstr?m's sensation-weighting theory, this result was accounted for by a smaller weighting coefficient for the first-presented stimulus than for the second. Time-order errors were negative on average, which was explained as the result of this weighting in conjunction with a low position of the reference level because of light background heaviness. With roving St, the dispersion of the subjective intrapair difference increased with St magnitude, providing evidence for Ekman's law (G. Ekman, 1956, 1959).