Transfer of calibration in dynamic touch: What do perceivers learn when they learn about length of a wielded object?

Successfully performing everyday behaviours requires that perceptions and actions are properly calibrated to environmental properties. In three experiments, the authors tested whether calibration was specific to perception of a particular property of a wielded object from a particular grasp position on that object. The experiments investigate whether transfer of recalibration occurs across changes in grasp position (Experiment 1), object property (Experiment 2), and grasp position and object property (Experiment 3). The results suggest that a complete transfer of recalibration occurred in each case. Such results are consistent with recent research on dynamic touch and suggest that rather than recalibrating participants to one particular property of the wielded objects, feedback about a particular property served to recalibrate participants to the properties of the rod set as a whole.     

Transfer of calibration in dynamic touch: what do perceivers learn when they learn about length of a wielded object?

Successfully performing everyday behaviours requires that perceptions and actions are properly calibrated to environmental properties. In three experiments, the authors tested whether calibration was specific to perception of a particular property of a wielded object from a particular grasp position on that object. The experiments investigate whether transfer of recalibration occurs across changes in grasp position (Experiment 1), object property (Experiment 2), and grasp position and object property (Experiment 3). The results suggest that a complete transfer of recalibration occurred in each case. Such results are consistent with recent research on dynamic touch and suggest that rather than recalibrating participants to one particular property of the wielded objects, feedback about a particular property served to recalibrate participants to the properties of the rod set as a whole.     

The role of feedback information for calibration and attunement in perceiving length by dynamic touch

Two processes have been hypothesized to underlie improvement in perception: attunement and calibration. These processes were examined in a dynamic touch paradigm in which participants were asked to report the lengths of unseen, wielded rods differing in length, diameter, and material. Two experiments addressed whether feedback informs about the need for reattunement and recalibration. Feedback indicating actual length induced both recalibration and reattunement. Recalibration did not occur when feedback indicated only whether 2 rods were of the same length or of different lengths. Such feedback, however, did induce reattunement. These results suggest that attunement and calibration are dissociable processes and that feedback informs which is needed. The observed change in variable use has implications also for research on what mechanical variables underlie length perception by dynamic touch.     

Direct Learning in Auditory Perception: An Information-Space Analysis of Auditory Perceptual Learning of Object Length

The theory of direct learning characterizes perception of a given property as occupying a locus in an information space and characterizes perceptual learning as continuous movement in that information space toward a more optimal locus. Three experiments investigated whether such an information-based account of learning could be applied to perceptual learning in audition. The results of Experiment 1 showed that perception of length by audition could be characterized as occupying a locus in an information space consisting of inertial variables that constrain perception of length by dynamic or effortful touch. Experiments 2 and 3 showed that feedback about length led to predictable movements across the information space from less optimal to more optimal loci. Such results provide additional support for the theory of direct learning and suggest that convergence information may be modality independent.     

Changing grasp position on a wielded object provides self-training for the perception of length

Calibration of perception to environmental properties typically requires experiences in addition to the perceptual task, such as feedback about performance. Recently, it has been shown that such experiences need not come from an external source or from a different perceptual modality. Rather, in some cases, a given perceptual modality can train itself. In this study, we sought to expand on the range of experiences in which this can occur for perception of the length of a wielded occluded object. Specifically, in two experiments, we investigated whether the act of perceiving the length of a wielded object from a given grasp position could recalibrate the perception of length from a different grasp position. In both experiments, three groups of participants perceived the lengths of wielded rods in a pretest, practice, and a posttest. The practice included either (a) experimenter feedback, (b) changing the grasp position on the object (and again attempting to perceive length), or (c) no additional experiences. In Experiment 1, participants changed their grasp position from the middle to the end of each rod, and in Experiment 2, they did so from the end to the middle of each rod. In both experiments, the results showed that perceiving length from a different grasp position can recalibrate (i.e., provide self-training for) the perception of length.     

Three-month-old infants' object recognition across changes in viewpoint using an operant learning procedure

Object knowledge refers to the understanding that all objects share certain properties. Various components of object knowledge (e.g., object occlusion, object causality) have been examined in human infants to determine its developmental origins. Viewpoint invariance--the understanding that an object viewed from different viewpoints is still the same object--is one area of object knowledge, however, that has received less attention. To this end, infants' capacity for viewpoint-invariant perception of multi-part objects was investigated. Three-month-old infants were tested for generalization to an object displayed on a mobile that differed only in orientation (i.e., viewpoint) from a training object. Infants were given experience with a wide range of object views (Experiment 1) or a more restricted range during training (Experiment 2). The results showed that infants generalized between a horizontal and vertical viewpoint (Experiment 1) that they could clearly discriminate between in other contexts (i.e., with restricted view experience, Experiment 2). Overall, the outcome shows that training experience with multiple viewpoints plays an important role in infants' ability to develop a general percept of an object's 3D structure and promotes viewpoint-invariant perception of multi-part objects; in contrast, restricting training experience impedes viewpoint-invariant recognition of multi-part objects.     

Transfer of calibration in length perception by dynamic touch

Earlier studies suggested that the calibration of actions is functionally, rather than anatomically, specific; thus, calibration of an action ought to transfer to actions that serve the same goal (Rieser, Pick, Ashmead, & Garing, 1995). In the present study, we investigated whether the calibration of perception also follows a functional organization: If one means of detecting an information variable is recalibrated, are other means of detection recalibrated as well? In two experiments, visual feedback was used to recalibrate perceived length of a rod wielded by the right hand; the recalibration was found to transfer to length perception with the left hand. This implies that calibration in perception is organized functionally rather than anatomically, and supports the general view that calibration applies to functional systems.     

An Information Space for Partial Length Perception in Dynamic Touch

Two experiments evaluated change in the perception of an environmental property (object length) in each of 3 perceptual modalities (vision, audition, and haptics) when perceivers were provided with the opportunity to experience the same environmental property by means of an additional perceptual modality (e.g., haptics followed by vision, vision followed by audition, or audition followed by haptics). Experiment 1 found that (a) posttest improvements in perceptual consistency occurred in all 3 perceptual modalities, regardless of whether practice included experience in an additional perceptual modality and (b) posttest improvements in perceptual accuracy occurred in haptics and audition but only when practice included experience in an additional perceptual modality. Experiment 2 found that learning curves in each perceptual modality could be accommodated by a single function in which auditory perceptual learning occurred over short time scales, haptic perceptual learning occurred over middle time scales, and visual perceptual learning occurred over long time scales. Analysis of trial-to-trial variability revealed patterns of long-term correlations in all perceptual modalities regardless of whether practice included experience in an additional perceptual modality.     

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.     

Learning From Gesture and Action: An Investigation of Memory for Where Objects Went and How They Got There

Speakers often use gesture to demonstrate how to perform actions—for example, they might show how to open the top of a jar by making a twisting motion above the jar. Yet it is unclear whether listeners learn as much from seeing such gestures as they learn from seeing actions that physically change the position of objects (i.e., actually opening the jar). Here, we examined participants' implicit and explicit understanding about a series of movements that demonstrated how to move a set of objects. The movements were either shown with actions that physically relocated each object or with gestures that represented the relocation without touching the objects. Further, the end location that was indicated for each object covaried with whether the object was grasped with one or two hands. We found that memory for the end location of each object was better after seeing the physical relocation of the objects, that is, after seeing action, than after seeing gesture, regardless of whether speech was absent (Experiment 1) or present (Experiment 2). However, gesture and action built similar implicit understanding of how a particular handgrasp corresponded with a particular end location. Although gestures miss the benefit of showing the end state of objects that have been acted upon, the data show that gestures are as good as action in building knowledge of how to perform an action.     

Perceiving action-relevant properties of tools through dynamic touch: effects of mass distribution, exploration style, and intention

At issue in the present series of experiments was the ability to prospectively perceive the action-relevant properties of hand-held tools by means of dynamic touch. In Experiment 1, participants judged object move-ability. In Experiment 2, participants judged how difficult an object would be to hold if held horizontally, and in Experiments 3 and 4, participants rated how fast objects could be rotated. In each experiment, the first and second moments of mass distribution of the objects were systematically varied. Manipulations of wielding speed and orientation during restricted exploration revealed perception to be constrained by (a) the moments of mass distribution of the hand-tool system, (b) the qualities of exploratory wielding movements, and (c) the intention to perceive each specific property. The results are considered in the context of the ecological theory of dynamic touch. Implications for accounts of the informational basis of dynamic touch and for the development of a theory of haptically perceiving the affordance properties of tools are discussed.     

Metamers for Hammer-With-Ability Are Not Metamers for Poke-With-Ability

Studies on dynamic (i.e., kinesthetic) touch perception have shown that perception of many properties of wielded objects are linked to variables related to the rotational inertia of those objects. The broad nature of the sensitivity to such variables invites the question of whether various perceived functional properties of wielded objects are distinct (i.e., whether they map to rotational inertia via different functions) or whether they are perceptually equivalent (i.e., whether they map to opposite extremes of the same function). Two experiments investigated whether hammer-with-ability and poke-with-ability are perceptually equivalent (i.e., metamers) using a metameric matching strategy. The results show that metamers for hammering were not metamers for poking, and vice versa. The results suggest that haptic perception of poke-with-ability and hammer-with-ability are distinct percepts.     

Congruency effects between auditory and tactile motion: Extending the phenomenon of cross-modal dynamic capture

Behavioral studies of multisensory integration in motion perception have focused on the particular case of visual and auditory signals. Here, we addressed a new case: audition and touch. In Experiment 1, we tested the effects of an apparent motion stream presented in an irrelevant modality (audition or touch) on the perception of apparent motion streams in the other modality (touch or audition, respectively). We found significant congruency effects (lower performance when the direction of motion in the irrelevant modality was incongruent with the direction of the target) for the two possible modality combinations. This congruency effect was asymmetrical, with tactile motion distractors having a stronger influence on auditory motion perception than vice versa. In Experiment 2, we used auditory motion targets and tactile motion distractors while participants adopted one of two possible postures: arms uncrossed or arms crossed. The effects of tactile motion on auditory motion judgments were replicated in the arms-uncrossed posture, but they dissipated in the arms-crossed posture. The implications of these results are discussed in light of current findings regarding the representation of tactile and auditory space.     

Principles of part-whole selective perception by dynamic touch extend to the torso

The haptic subsystem of dynamic touch expresses a novel form of part-whole selective perception. When wielding a nonvisible rod grasped at some intermediate point along its length, an individual can attend to and report the length of a part of the rod (e.g., the segment forward of the hand) or the length of the whole rod. Both perceptions relate to the rod's mass moments about the point of grasp but in systematically different ways. Previous demonstrations of this part-whole selectivity have been in respect to rods grasped by hand or attached to a foot. The authors demonstrated the part-whole selectivity for nonvisible rods attached to the shoulder girdle and wielded primarily by movements of the trunk with benchmark performance provided by the same rods grasped and wielded by hand. Their results suggest that part-whole selectivity is a haptic capability general to the body.     

Perceptual Learning of Tooling Affordances of a Jointed Object via Dynamic Touch

We investigated whether perceptual learning via dynamic touch can facilitate the discovery of tooling affordances. Twelve blindfolded participants manipulated two structurally identical aluminum objects consisting of a blade and a shaft; one object was seven and a half times heavier than and twice as large as the other object. Flexions/extensions at two joints in the shaft changed the configuration and functionality of each object. A rigid shaft (one of four possible configurations) rendered each object a functional hoe. The number of changes in the configuration produced prior to determining that the grasped object had been rendered a functional hoe greatly exceeded the number of possible configurations and declined with experience, whereas the rate of change in configuration increased with experience. Inertial properties specifically support perception via dynamic touch and explained the observed differences in actions with the two objects. These findings demonstrate that perceptual learning via dynamic touch can facilitate the discovery of tooling affordances.     

Perceiving by Dynamic Touch the Distances Reachable With Irregular Objects

Observers wielded occluded objects and reported the distances reachable with the distal tips of the objects. Each object consisted of a cylindrical stem with two branches attached perpendicularly along its length; stem and branch lengths varied across objects. In Experiment 1, the branches were 180 deg. apart, both attached halfway along the stem. In Experiment 2, the branches were 180 deg. apart, one at one fourth and the other at three fourths of the stem length. In Experiment 3, the branches were 90 deg. apart, one at one fourth and the other at three fourths of the stem length. Observers had no foreknowledge of the objects' shapes. In each experiment, perceived reachable distance was found to be dependent on the maximum eigenvalue of the object's inertia tensor computed about the point of rotation in the wrist. Discussion focused on (a) quantifying shape for dynamic touch through the inertia ellipsoid, (b) the significance of the inertia tensor to the spatial abilities of dynamic touch, and (c) contrasting bases for theories of space perception (Lotze vs. Gibson).     

Recalibrating positive and negative weighting tendencies in attitude generalization

Individual differences in the weighting of positive versus negative information when generalizing attitudes towards novel objects predict a variety of assessments that involve the integration of valence information (Pietri, Fazio, & Shook, 2013). The goal of the current research was to manipulate valence weighting in attitude generalization to demonstrate its causal impact on various judgments and behaviors. In four experiments, participants first played BeanFest—a game in which they approached/avoided novel stimuli (beans) varying in shape and speckles, in order to increase and not decrease their points (Fazio et al., 2004). Following the game, participants classified game beans, and novel ones that varied in resemblance to the game beans as either positive or negative. In the recalibration condition, participants were told whether each classification was or was not correct. Thus, they received feedback regarding the appropriate valence weighting of resemblance to a known positive versus a known negative. In Experiment 1, this recalibration influenced individuals' attitude generalizations regarding other (non-bean) novel objects. We then examined if recalibration would produce far-transferring effects by influencing interpretations of ambiguous situations (Experiment 2), risk assessments (Experiment 3), and finally risk-taking behavior (Experiment 4). Across the four experiments, the recalibration procedure led participants who were initially relatively cautious to be more positive when making these various judgments, whereas people who exhibited an initial risky bias became more negative as a function of recalibration.     

Head up, foot down: object words orient attention to the objects' typical location

Many objects typically occur in particular locations, and object words encode these spatial associations. We tested whether such object words (e.g., head, foot) orient attention toward the location where the denoted object typically occurs (i.e., up, down). Because object words elicit perceptual simulations of the denoted objects (i.e., the representations acquired during actual perception are reactivated), we predicted that an object word would interfere with identification of an unrelated visual target subsequently presented in the object's typical location. Consistent with this prediction, three experiments demonstrated that words denoting objects that typically occur high in the visual field hindered identification of targets appearing at the top of the display, whereas words denoting low objects hindered target identification at the bottom of the display. Thus, object words oriented attention to and activated perceptual simulations in the objects' typical locations. These results shed new light on how language affects perception.     

Self-training of dynamic touch: Striking improves judgment by wielding

In traditional theories of perceptual learning, sensory modalities support one another. A good example comes from research on dynamic touch, the wielding of an unseen object to perceive its properties. Wielding provides the haptic system with mechanical information related to the length of the object. Visual feedback can improve the accuracy of subsequent length judgments; visual perception supports haptic perception. Such cross-modal support is not the only route to perceptual learning. We present a dynamic touch task in which we replaced visual feedback with the instruction to strike the unseen object against an unseen surface following length judgment. This additional mechanical information improved subsequent length judgments. We propose a self-organizing perspective in which a single modality trains itself.