The role of effective lever length in the perception of lifted weights

Objects are lifted through a system of body levers and, since the force required to lift objects decreases as the effective lever length is shortened, it was hypothesized that the perceived heaviness of objects would be less when they were lifted with the elbow bent than with it extended. Cans lifted from greater initial angles were consistently judged to be lighter by blindfolded Ss.     

The measurement of differential thresholds for lifted weights by microcomputer-controlled apparatus

The measurement of differential thresholds (DLs) for lifted weights normally involves lengthy test sessions. This is due partly to the statistical techniques for measuring the threshold and partly to the methods adopted to present the stimuli. Attempts to speed up test procedures tend to produce unreliable DL estimates, or to measure the sense of force or effort rather than weight perception. To facilitate the measurement of DLs for lifted weights, an Apple microcomputer was programmed to generate Wetherill tracking procedures and was interfaced with two stimulus bearing turntables. Various lifting methods are easily implemented, and DLs are reliably and quickly measured. The adaptation of the apparatus for general use in investigating the haptic sense modality is discussed.     

Mechanical advantage in the size-weight illusion

When a hand-held object is lifted by wrist flexion, the lifting system composed of muscles, bones, and the object lifted constitutes a third-class lever. Therefore, objects require greater lifting force as they are supported further distally The small can of the DeMoors size-weight illusion cans is usually supported further distally than the large one, possibly influencing their relative perceived weight When Ss are required to lift the small can through a shorter lever than the large one, there is a significant shift of judgments toward a reversal of the SWI in a paired-comparison situation. It is concluded that mechanical advantage does influence weight judgments and that biomechanical factors should be considered whenever weight judgments are made.     

The effect of timing of a perturbation on the execution of a lifting movement

Anticipation to the mass magnitude is important in lifting, but underestimation of a mass, in contrast to overestimation, does not cause major movement disturbances. This may be caused by corrections in muscle activity before the object is actually lifted. This study was designed to assess the importance of these corrections during the loading phase for the execution of a lifting movement when the mass is underestimated. Ten subjects lifted a box (1.6 kg), of which the mass was increased by 10 kg without them knowing so. The mass was added either before the box had been lifted from the ground (perturbation before lift-off, PBL) or right perturbation after lift-off (PAL). In the PBL condition back muscle activity was increased before lift-off. Even though this early corrective response could obviously not occur in the PAL condition, the lifting movement was executed without clear problems. In sum, corrections in muscle activity before lift-off are not necessary for adequate correction of a perturbation induced by an unexpected heavier object.     

Perception of Kinematic Characteristics in the Motion of Lifted Weight

It has been widely shown that human observers are able to perceive lifted weight from the observation of a point-light display of the lifter's action. In the experiments reported here, the kinematic information used by observers to perceive a lifted weight was determined. In Experiment 1, observers (N equals: 30) were able to identify weights (5, 10, 15, 20, and 25 kg) successfully by observing only the lift phase of the action. Other procedures, such as walking while holding the weight and placing the weight on a table, did not result in significantly improved estimations. In Experiment 2, the kinematic patterns used by 4 lifters with weights varying from 5 to 25 kg were examined. Changes in weight lifted resulted in changes in lift velocity, hip angle, and dwell time. In Experiment 3, in which 15 observers participated, these 3 kinematic variables were experimentally manipulated. The results indicated that observation was most significantly influenced by variations in lift velocity. The results are discussed in relation to kinematic specification of dynamics and heuristic approaches.     

Time error in lifted weights as affected by presentation order and judgment mode

In the method of constant stimulus differences, results obtained under two presentation orders (standard first and standard second) are commonly combined to eliminate time error. The present study shows that this technique is not adequate for controlling time error as the presentation orders have differential effects upon PSE. Using a two-handed technique, 96 subjects judged lifted weights on the comparative rating scale. The subjects lifted the standard before, with, or after the variable stimulus. They also either judged the standard in terms of the variable or the variable in terms of the standard (mode of judgment). Judgment mode, a previously uninvestigated confounding variable of presentation order was not an important factor in influencing the value of the PSE.     

Kinematic form and scaling: further investigations on the visual perception of lifted weight

Observers are able to judge accurately the weight lifted by another person when only the motions of reflective patches attached to the lifter's major limb joints and head can be seen (Runeson & Frykholm, 1981). What properties of these complex kinematic patterns allow judgments of weight to be made? The pattern of variation in velocity of the lifted object over position is explored as a source of information for weight: It is found to provide limited information. How are variations in kinematic patterns scaled to allow judgments of weight, a kinetic quantity? The possibility of a source of information for scaling in the kinematics is investigated. Judgments based only on patch-light displays are accurate to a degree that is improved by an extrinsic scaling basis. Finally, the sensitivity to scaling of alternative metrics used in judging is explored. Intrinsic metrics are discovered to be less sensitive to the absence of an extrinsic basis for scaling.     

Impaired visual perception of hurtful actions in patients with chronic low back pain

Visually presented biological motion stimuli activate regions in the brain that are also related to musculo-skeletal pain. We therefore hypothesized that chronic pain impairs the perception of visually presented actions that involve body parts that hurt. In the first experiment, chronic back pain (CLBP) patients and healthy controls judged the lifted weight from point-light biological motion displays. An actor either lifted an invisible container (5, 10, or 15 kg) from the floor, or lifted and manipulated it from the right to the left. The latter involved twisting of the lower back and would be very painful for CLBP patients. All participants recognized the displayed actions, but CLBP patients were impaired in judging the difference in handled weights, especially for the trunk rotation. The second experiment involved discrimination between forward and backward walking. Here the patients were just as good as the controls, showing that the main result of the first experiment was indeed specific to the sensory aspects of the task, and not to general impairments or attentional deficits. The results thus indicate that the judgment of sensorimotor aspects of a visually displayed movement is specifically affected by chronic low back pain.     

Is caching the key to exclusion in corvids? The case of carrion crows (Corvus corone corone)

Recently, two corvid species, food-caching ravens and non-caching jackdaws, have been tested in an exclusion performance (EP) task. While the ravens chose by exclusion, the jackdaws did not. Thus, foraging behaviour may affect EP abilities. To investigate this possibility, another food-caching corvid species, the carrion crow (Corvus corone corone), was tested in the same exclusion task. We hid food under one of two cups and subsequently lifted either both cups, or the baited or the un-baited cup. The crows were significantly above chance when both cups were lifted or when only the baited cup was lifted. When the empty cup was lifted, we found considerable inter-individual variation, with some birds having a significant preference for the un-baited but manipulated cup. In a follow-up task, we always provided the birds with the full information about the food location, but manipulated in which order they saw the hiding or the removal of food. Interestingly, they strongly preferred the cup which was manipulated last, even if it did not contain any food. Therefore, we repeated the first experiment but controlled for the movement of the cups. In this case, more crows found the food reliably in the un-baited condition. We conclude that carrion crows are able to choose by exclusion, but local enhancement has a strong influence on their performance and may overshadow potential inferential abilities. However, these findings support the hypothesis that caching might be a key to exclusion in corvids.     

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.     

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.     

Manual exploration and the perception of slipperiness

In this article, we report on two experiments that examined the haptic perception of slipperiness. The first experiment aimed to determine whether the type of finger motion across a surface influenced the ability to accurately judge the frictional coefficient (or slipperiness) of that surface. Results showed that when using static contact, participants were not as good at distinguishing between various surfaces, compared with when their finger moved across the surface. This raises the issue of how humans are able to generate the appropriate forces in response to friction during grasping (which involves static finger contact). In a second study, participants lifted objects with surfaces of varying coefficients of friction. The participants were able to accurately perceive the slipperiness of the surfaces that were lifted; however, the grasping forces were not scaled appropriately for the friction. That is, there was a dissociation between haptic perception and motor output.     

The number–weight illusion

Psychonomic Bulletin & Review - When objects are manually lifted to compare their weight, then smaller objects are judged to be heavier than larger objects of the same physical weights: the...     

Static one-legged balance in soccer players during use of a lifted leg

The goal was to describe static one-legged balance during use of a lifted leg and to compare balance between the dominant and nondominant legs of soccer players. Participants were 17 male soccer players and 17 untrained male students (control). Balance ability was evaluated with four sway measures: sway velocity, anterior-posterior sway, medial-lateral sway, and high-frequency sway. Soccer players had smaller magnitude mean anterior-posterior and medial-lateral sway than untrained students. Although mean sway velocity and anterior-posterior sway were higher with the dominant leg than in the nondominant leg of the control group, there was no significant difference on any sway factor between the two legs of the soccer group. In conclusion, the soccer players were observed to have superior static one-legged balance during use of a lifted leg, and there is no difference in balance for the two legs in the soccer group.     

Grasping the concept of personal property

The concept of property is integral to personal and societal development, yet understanding of the cognitive basis of ownership is limited. Objects are the most basic form of property, so our physical interactions with owned objects may elucidate nuanced aspects of ownership. We gave participants a coffee mug to decorate, use and keep. The experimenter also designed a mug of her own. In Experiment 1, participants performed natural lifting actions with each mug. Participants lifted the Experimenter’s mug with greater care, and moved it slightly more towards the Experimenter, while they lifted their own mug more forcefully and drew it closer to their own body. In Experiment 2, participants responded to stimuli presented on the mug handles in a computer-based stimulus–response compatibility task. Overall, participants were faster to respond in trials in which the handles were facing in the same direction as the response location compared to when the handles were facing away. The compatibility effect was abolished, however, for the Experimenter’s mug – as if the action system is blind to the potential for action towards another person’s property. These findings demonstrate that knowledge of the ownership status of objects influences visuomotor processing in subtle and revealing ways.     

Gesture changes thought by grounding it in action

When people talk, they gesture. We show that gesture introduces action information into speakers' mental representations, which, in turn, affect subsequent performance. In Experiment 1, participants solved the Tower of Hanoi task (TOH1), explained (with gesture) how they solved it, and solved it again (TOH2). For all participants, the smallest disk in TOH1 was the lightest and could be lifted with one hand. For some participants (no-switch group), the disks in TOH2 were identical to those in TOH1. For others (switch group), the disk weights in TOH2 were reversed (so that the smallest disk was the heaviest and could not be lifted with one hand). The more the switch group's gestures depicted moving the smallest disk one-handed, the worse they performed on TOH2. This was not true for the no-switch group, nor for the switch group in Experiment 2, who skipped the explanation step and did not gesture. Gesturing grounds people's mental representations in action. When gestures are no longer compatible with the action constraints of a task, problem solving suffers.     

Evaluating Effort: Influences of Evaluation Mode on Judgments of Task‐specific Efforts

The claim that humans adapt their actions in ways that avoid effortful processing (whether cognitive or physical) is a staple of various theories of human behavior. Although much work has been carried out focusing on the determinants of such behaviors, less attention has been given to how individuals evaluate effort. In the current set of experiments, we utilized the general evaluability theory to examine the evaluability of effort by examining subjective value functions across different evaluation modes. Individuals judged the anticipated effort of four task‐specific efforts indexed by stimulus rotation, items to be remembered, weight to be lifted, and stimulus degradation across joint (i.e., judged comparatively) and single evaluation modes (i.e., judged in isolation). General evaluability theory hypothesizes that highly evaluable attributes should be consistently evaluated (i.e., demonstrate similar subjective value functions) between the two modes. Across six experiments, we demonstrate that the perceived effort associated with items to be remembered, weight to be lifted, and stimulus degradation can be considered relatively evaluable, while the effort associated with stimulus rotation may be relatively inevaluable. Results are discussed within the context of subjective evaluation, internal reference information, and strategy selection. In addition, methodological implications of evaluation modes are considered. Copyright © 2017 John Wiley & Sons, Ltd.     

The voice of the counselee

Conclusion Unfortunately, case excerpts and histories in which the voice of counselee is largely ignored appear very frequently in the pastoral care and counseling literature. More unfortunately, these excerpts are often lifted up, as is the one discussed in this article, as examples of very good counseling. The plea from the counselees, which can be heard very clearly through these excerpts and histories, is quite simply that their voices be heard and their experiences of their own suffering validated.     

The validity of using prior ratings of perceive exertion to regulate resistance exercise intensity

This investigation examined the validity of using ratings of perceived exertion (RPE) to regulate intensity during resistance exercise. 19 male (M age = 22.2 yr., SD = 2.7) and 19 female (M age = 21.4 yr., SD = 2.3) participants estimated exertion when performing the knee extension at 40% to 90% of one-repetition maximum. One week later, participants were asked to produce weights for the knee extension that elicited the feelings of exertion associated with 9, 13, and 17 on the Borg RPE scale. The weight produced at 9, 13, and 17 during the production session was compared to the weight lifted at each RPE during the estimation session. The effect sizes associated with the differences in weight lifted across sessions at each RPE were generally small in magnitude, especially at the higher intensities (ES = .40, -.09, .15, respectively). The results of this investigation support the use of RPE as a method of prescribing the intensity of resistance exercise.     

In defence of an Indian approach to the psychology of emotion

The indigenous Indian approach to the psychology of emotions, which originated in Bharata's ancient classical work called the Nāṭyaśāstra, is articulated and its conceptual structure is situated in the contemporary psychological scholarship and the discourse on emotion. In particular an analysis of Bhakti Rasa is presented to illustrate how life gets transformed and lifted to higher levels of spirituality. The issues pertaining to theory and method in appreciating psychological reality are examined. It is concluded that emotions are complex phenomena that need different “paradigms” appropriate for understanding the different aspects.