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...     

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 influence of the interaction of weight and volume on subjective heaviness

A model previously proposed for the size-weight illusion (Cross & Rotkin, 1975) was found unsatisfactory because the postulated volume parameter was not independent of the unit of measurement of weight and the model yielded a paradoxical prediction that the perceived heaviness of small objects should decrease as their weight increased. A new model was proposed based on Stevens and Rubin’s (1970) finding that heaviness functions are a family of con-verging power functions and some of Cross and Rotkin’s developments. The model was ex-amined by estimating its parameters from data previously reported by Cross and Rotkin, Stevens and Rubin, and Kolehmainen and Mikkonen (1970). The equations was found to fit each set of data well. Four independent estimates of a volume parameter of the model were in close agreement, .18, .21, .21, and .24, which is consistent with the model. nt]mis|This research was supported by Grants A0151 and A9582 from the National Research Council of Canada.     

Subjective ratios and differences in perceived heaviness

In previous studies, judgments of ratios and differences in subjective magnitude have yielded similar orders, consistent with a hypothesis that a single perceived relation underlies both judgment tasks. In the present research, 15 subjects estimated heaviness differences between 28 pairs of eight weights and each of 8 groups of 10 subjects evaluated heaviness ratios of eight variable stimuli with respect to a different standard stimulus. Presenting stimuli that were equally spaced on a cube-root scale of weight enhanced expected ordinal discrepancies between ratio and difference estimates, and employing independent groups for each standard stimulus in ratio estimation eliminated a possible bias due to varying standards within the presentation sequence. Differences in orders of ratio and difference estimates together with differences in scales obtained from non-metric analyses in terms of a difference model indicated that the judgments were based on two perceived relations that are ordinally consistent with arithmetic operations of ratios and differences. A ratio scale of heaviness was derived from the combined orders of subjective ratios and differences.     

Rotational inertia and multimodal heaviness perception

Perceived heaviness of wielded objects has been shown to be a function of the objects’ rotational inertia—the objects’ resistance to rotational acceleration. Studies have also demonstrated that if virtual objects rotate faster than the actual wielded object (i.e., a rotational gain is applied to virtual object motion), the wielded object is perceived as systematically lighter. The present research determined whether combining those inertial and visual manipulations would influence heaviness perception in a manner consistent with an inertial model of multimodal heaviness perception. Rotational inertia and optical rotational gain of wielded objects were manipulated to specify inertia multimodally. Both visual and haptic manipulations significantly influenced perceived heaviness. The results suggest that rotational inertia is detected multimodally and that multimodal heaviness perception conforms to an inertial model.     

Contributions of weight perceptions to weight loss attempts: Differences by body mass index and gender

Previous studies have consistently observed that women are more likely to perceive themselves as overweight compared to men. Similarly, women are more likely than men to report trying to lose weight. Less is known about the impact that self-perceived weight has on weight loss behaviors of adults and whether this association differs by gender. We conducted a cross-sectional analysis among an employee sample (n = 899) to determine the association of self-perceived weight on evidence-based weight loss behaviors across genders, accounting for body mass index (BMI) and demographic characteristics. Women were more likely than men to consider themselves to be overweight across each BMI category, and were more likely to report attempting to lose weight. However, perceiving oneself to be overweight was a strong correlate for weight loss attempts across both genders. The effect of targeting accuracy of self-perceived weight status in weight loss interventions deserves research attention.     

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).     

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.     

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).     

Neural activity in relation to temporal distance: Differences in past and future temporal discounting

This study investigated the differences between past and future temporal discounting in terms of neural activity in relation to temporal distance. Results show that brain regions are engaged differently in past and future temporal discounting. This is likely because past temporal discounting requires memory reconstruction, whereas future temporal discounting requires the processing of uncertainty about the future. In past temporal discounting, neural activity differed only when preferences were made between rewards received one hour prior and rewards received further in the past. The peak amplitudes of P2 and P3 varied as the temporal distance increased from 2 weeks to 50 years. In future temporal discounting, neural activity differed only when preferences were evaluated between two delayed rewards. The delay conditions (6 months:5 years) and (6 months:50 years) had a significant influence on P2 and N2. Findings indicate the existence of different decision-making systems operating in past and future temporal discounting.     

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...     

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.     

Sex differences in the relation of children's height and weight to academic performance and others' attributions of competence

The purposes of the present study were to examine the relation of elementary-school girls' and boys' height and weight to (a) teachers' and peers' perceptions of the children's independence and academic, athletic, and social competence; and (b) children's achievement test scores and grades. Teachers rated kindergarteners' through fourth graders' competence both at the beginning of the school year and four months later; first and third graders rated their peers' competence once midyear. In general, size and/or bulk were positively related to teachers' attributions of competence, grades, and achievement test scores for boys, especially for the older boys. Heaviness was negatively related to teachers' ratings of females' competence (especially athletic competence and especially for older girls). Moreover, large size (height not controlling for weight) was positively related to younger but not older children's nominations of males for athletic ability. The results are discussed in terms cultural stereotypes and their implications for the development of children's competence.     

Differences in locus of control between obese adult and adolescent females undergoing weight reduction

Rotter's (1966) Internal-External (I-E) Scale was administered to 65 adult and adolescent females in two outpatient obesity treatment programs. The adults were significantly higher in internal locus of control (LOC) and the adolescents higher in external LOC. These differences suggest that although the adults felt limited control over their weight and eating behavior, this did not reflect a lack of perceived control over other factors in their lives. In contrast, the adolescents appeared to feel that they had limited control over an array of factors in their lives.     

Differences in American English, Spanish, and monkey perception of thesay-stay trading relation

An interesting phenomenon in human speech perception is the trading relation, in which two different acoustic cues both signal the same phonetic percept. The present study compared American English, Spanish, and monkey listeners in their perception of the trading relation between gap duration andFl transition onset frequency in a syntheticsay-stay continuum. For all the subjects, increased gap duration caused perception to change fromsay tostay; however, subjects differed in the extent to which theFl cue traded with gap duration. For American English listeners, a change from a low to a highF1 onset caused a phoneme boundary shift of 26 msec toward shorter gap durations, indicating a strong trading relation. For Spanish listeners, the shift was significantly smaller at 13.7 msec, indicating a weaker trading relation. For monkeys, there was no shift at all, indicating no trading relation. These results provide evidence that thesay-stay trading relation is dependent on perceptual learning from linguistic exposure.     

不同相关线索下海洛因成瘾者的反应差异及反应抑制特征：来自ERP的证据

采用ERP技术, 探究海洛因成瘾者在不同相关线索下的脑电反应及其与冲动性的关系。实验采用组间实验设计和双选择Oddball范式, 要求海洛因成瘾组和健康对照组被试对标准刺激与偏差刺激分别做不同的按键反应, 记录他们的EEG数据。结果发现：相比对照组被试, 海洛因成瘾者在观看药物相关线索时诱发的N2波幅更小, P3波幅更大; 在成瘾组内, 相比用药工具线索, 用药动作线索诱发了更小的N2波幅和更大的P3波幅。这表明海洛因成瘾者对药物相关线索存在反应抑制缺陷, 且不同的药物相关线索会激发海洛因成瘾者不同程度的反应抑制缺陷, 用药动作线索比用药工具线索更大程度地影响成瘾者的反应抑制能力, 反映出更高的动作冲动性。     

Affordance, proper function, and the physical basis of perceived heaviness

The physical basis of perceived heaviness requires consideration of the haptic perceptual system's role in controlling actions (the system's proper function) and the relation of an object's inertial properties to properties of the human movement system (the object's affordance). We show that the mass of a wielded object and particular scalar variables calculated from the object's inertia tensor combine linearly in determining perceived heaviness. The tensor-derived scalars reflect the symmetry and volume of the corresponding inertia ellipsoid. These measures bear directly on the object's wieldability, that is, on the patterning and level of muscular forces required to move the object in a controlled fashion.     

Differences in Parental Investment Contribute to Important Differences Between Men and Women

Parental investment theory addresses sex differences that result from the trade-off between parenting effort and mating effort. For example, relative to men, women spend more time caring for offspring, are more selective in assenting to sexual intercourse, are more upset by a partner's emotional infidelity than by a partner's sexual infidelity, and are better able to inhibit their behaviors in certain situations. These and other sex differences are attributable to evolved mechanisms that work in interaction with the physical and social environments.