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.     

Dispositional Theories of the Colours of Things

Dispositional theories of the colours of objects identify an object’s having a certain colour with its being such that it would produce perceptions of certain kinds in perceivers of certain kinds under certain specified conditions. Without doubting that objects have dispositions to produce perceptions of certain kinds, this paper questions whether the relevant kinds of perceptions, perceivers, and conditions can be specified in a way that (i) does not rely on acceptance of any objects as being coloured in a non-dispositional sense and (ii) secures the necessity of the identity between an object’s having the disposition so specified and its having the colour in question. Accepting any theory that looked as if it succeeded on both these counts would require an explanation of why a parallel identity does not hold for an object’s disposition to produce, e.g., perceptions of shape.     

When can an object feel heavier than itself? Perceived heaviness of a wielded object depends on grasp position

Perceived heaviness is a function of how an object resists being moved, and such resistance is determined by object mass and the distribution of that mass relative to the wrist. Whereas mass is independent of grasp position on an object, distribution of mass relative to the wrist is not. Therefore, perceived heaviness should vary with grasp position. Blindfolded participants wielded internally weighted cylindrical objects while grasping them at different distances from the centre of mass. They rated how heavy each object felt at each location relative to a standard object. The results show that objects felt heavier as they were grasped farther from the centre of mass, highlighting the role of the touch system in controlling movement.     

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.     

Statues and Lumps: A Strange Coincidence?

Puzzles about persistence and change through time, i.e., about identity across time, have foundered on confusion about what it is for ‘two things’ to be have ‘the same thing’ at a time. This is most directly seen in the dispute over whether material objects can occupy exactly the same place at the same time. This paper defends the possibility of such coincidence against several arguments to the contrary. Distinguishing a temporally relative from an absolute sense of ‘the same’, we see that the intuition, ‘this is only one thing’, and the dictum, ‘two things cannot occupy the same place at the same time’, are individuating things at a time rather than absolutely and are therefore compatible with coincidence. Several other objections philosophers have raised ride on this same ambiguity. Burke, originating what has become the most popular objection to coincidence, argues that if coincidence is possible there would be no explanation of how objects that are qualitatively the same at a time could belong to different sorts. But we can explain an object’s sort by appealing to its properties at other times. Burke’s argument to the contrary equivocates on different notions of ‘cross-time identity’ and ‘the statue’. From a largely negative series of arguments emerges a positive picture of what it means to say multiple things coincide and of why an object’s historical properties explain its sort rather than vice versa – in short, of how coincidence is possible.     

Rea’s Revenge and the Persistent Problem of Persistence for Realism

Realism about material objects faces a variety of epistemological objections. Recently, however, some realists have offered new accounts in response to these long-standing objections; many of which seem plausible. In this paper, I raise a new objection against realism vis-à-vis how we could empirically come to know mind-independent essential properties for objects. Traditionally, realists hold kind-membership and persistence as bound together for purposes of tracing out an object’s essential existence conditions. But I propose kind-membership and persistence for objects can conceptually come apart and function epistemologically distinctly from one another—in which case the usual reliance by realists on an assumption of persistence to determine kind-membership conditions is unjustified. Thus, present realist attempts to explain how empirical detection of mind-independent essential properties for objects could possibly occur inevitably results in circularity. The charge against the realist is to explain why we don’t have to first discover persistence conditions for an object before we can ascertain kind-membership conditions for an object. If no answer is forthcoming, then it seems the weight of the epistemological objection to realism is back in full force.     

Biased competition and visual search: the role of luminance and size contrast

The biased-competition theory of attention proposes that objects compete for cortical representation in a mutually inhibitory network; competition is biased in favor of the attended item. Here we test two predictions derived from the biased-competition theory. First we assessed whether increasing an object’s relative brightness (luminance contrast) biased competition in favor of (i.e., prioritized) the brighter object. Second we assessed whether increasing an object’s size biased competition in favor of the larger object. In fulfillment of these aims we used an attentional capture paradigm to test whether a featural singleton (an item unique with respect to a feature such as size or brightness) can impact attentional priority even when those features are irrelevant to finding the target. The results support the prediction that a singleton with respect to luminance contrast receives attentional prioritization and extend the biased-competition account to include size contrast, because a large singleton also receives attentional prioritization.     

Basic-level kinds and object persistence

In three experiments, we explored the basis of adults’ judgments of individual object persistence through transformation. Participants watched scenarios in which an object underwent a transformation into an object belonging to the same or a different basic-level kind. Participants were queried about the object’s persistence through the transformation as an individual (indexed by its proper name) and as a member of the original kind (indexed by its basic-level count noun in Experiments 1 and 2, or by its superordinate-level noun in Experiment 3). In all experiments, participants rated objects that were altered in a way that maintained basic-level kind to be less likely to retain their proper name than those that were altered in a way that changed basic-level kind. These findings suggest that shared basic-level kind membership serves as a dimension of similarity over which objects’ unique individual identities are highlighted. We discuss the implications of the results for existing theoretical accounts of adults’ judgments of individual object persistence.     

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.     

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.     

Vision-for-action: The effects of object property discrimination and action state on affordance compatibility effects

When a person views an object, the action the object evokes appears to be activated independently of the person’s intention to act. We demonstrate two further properties of this vision-to-action process. First, it is not completely automatic, but is determined by the stimulus properties of the object that are attended. Thus, when a person discriminates the shape of an object, action affordance effects are observed; but when a person discriminates an object’s color, no affordance effects are observed. The former, shape property is associated with action, such as how an object might be grasped; the latter, color property is irrelevant to action. Second, we also show that the action state of an object influences evoked action. Thus, active objects, with which current action is implied, produce larger affordance effects than passive objects, with which no action is implied. We suggest that the active object activates action simulation processes similar to those proposed in mirror systems.     

Prospective object search in dogs: mixed evidence for knowledge of <Emphasis Type="Italic">What</Emphasis> and <Emphasis Type="Italic">Where</Emphasis>

We investigated whether two dogs that had been specially trained to retrieve objects by their names were able to integrate information about the identity (What) as well as the location (Where) of those objects so that they could plan their search accordingly. In a first study, two sets of objects were placed in two separate rooms and subjects were asked to retrieve the objects, one after the other. Both dogs remembered the identity of the objects as they reliably retrieved the correct objects. One of the dogs was also able to integrate information about the object’s location as he chose the correct location in which the object had been placed. Further investigation of the second dog’s behavior revealed that she followed a more stereotyped search strategy. Despite this variation in performance, this study provides evidence for the memory of What and Where in a domestic dog and shows the prospective use of such information in a search task.     

Heuristics and invariants in dynamic event perception: Immunized concepts or nonstatements?

There is ample evidence showing that observers are able to judge dynamic properties of moving objects on the basis of visual kinematics. It is, however, widely disputed as to how to explain this body of data. While direct perceptionists claim that observers have direct access to the underlying dynamics of the event (kinematic specification of dynamics, or KSD, principle), contenders of the perceptual heuristics approach (PH) suggest that observers use the visual equivalent of a heuristic to arrive at their judgments about dynamics. First, the critical assumptions of the KSD principle are discussed in order to motivate the claim that the KSD principle cannot be falsified and is thus immune to empirical criticism. Then the same scrutiny is applied to the PH approach. It is, in its general form at least, afflicted with a similar lack of falsifiability. In comparing the concepts underlying invariants and perceptual heuristics, my conclusion is that a critical experiment aimed at deciding between the two approaches is impossible, and that KSD and PH can be regarded as nonstatements. The findings reported in the event-perception literature must therefore be reevaluated on these grounds.     

How to Define Extrinsic Properties

There are, broadly, three sorts of account of intrinsicality: ‘self-sufficiency’, ‘essentiality’ and ‘pure qualitativeness’. I argue for the last of these, and urge that we take intrinsic properties of concrete objects to be all and only those shared by actual or possible duplicates, which only differ extrinsically. This approach gains support from Francescotti’s approach: defining ‘intrinsic’ in contradistinction to extrinsic properties which ‘consist in’ relations which rule out intrinsicality. I answer Weatherson’s criticisms of Francescotti, but, to answer criticisms of my own, I amend his account, proposing that possession of an extrinsic property consists in a relation to one or more actual or possible distinct concrete objects. Finally I indicate ways to avoid some apparent objections to this account.     

Phonological priming effects on speech onset latencies and viewing times in object naming

An earlier experiment (Meyer, Sleiderink, & Levelt, 1998) had shown that speakers naming object pairs usually inspected the objects in the required order of mention (left object first) and that the viewing time for the left object depended on the word frequency of its name. In the present experiment, object pairs were presented simultaneously with auditory distractor words that could be phonologically related or unrelated to the name of the object to be named first. The speech onset latencies and the viewing times for that object were shorter after related distractors than after unrelated distractors. Since this phonological priming effect, like the word frequency effect, most likely arises during wordform retrieval, we conclude that the shift of gaze from the first to the second object is initiated after the word form of the first object’s name has been accessed.     

Habermas on Understanding: Virtual Participation,Dialogue and the Universality of Truth

Although the success of Habermas’s theory of communicative action depends on his dialogical model of understanding in which a theorist is supposed to participate in the debate with the actors as a ‘virtual participant’ and seek context-transcendent truth through the exchange of speech acts, current literature on the theory of communicative action rarely touches on the difficulties it entails. In the first part of this paper, I will examine Habermas’s argument that understanding other cultural practices requires the interpreter to virtually participate in the “dialogue” with the actors as to the rationality of their cultural practice and discuss why, according to Habermas,such dialogue leads to the “context-transcendent truth”. In the second part, by using a concrete historical example, I will reconstruct a “virtual dialogue” between Habermas and Michael Polanyi as to the rationality of scientific practice and indicate why Habermas’s dialogical model of understanding based on the methodology of virtual participation cannot achieve what it professes to do.     

Impetus beliefs as default heuristics: Dissociation between explicit and implicit knowledge about motion

We examined the extent to which findings from the literature on naive physics and representational momentum studies are consistent with impetus beliefs postulating imparted internal energy as a source of motion. In a literature review, we showed that, for situations in which impetus theory and physical principles make different predictions, representational momentum effects are consistent with impetus beliefs. In three new experiments, we examined people’s implicit and explicit knowledge of the effect of mass on the rate of ascending motion. The results suggest that implicit knowledge is consistent with impetus theory and is unaffected by explicit knowledge. Expert physicists, whose explicit knowledge is in accord with Newtonian principles, exhibited the same implicit impetus beliefs as novices when asked to respond in a representational momentum paradigm. We propose that, in situations in which an immediate response is required and one does not have specific contextual knowledge about an object’s motion, both physics experts and novices apply impetus principles as a default heuristic.     

The effects of occlusion and past experience on the allocation of object-based attention

There is considerable evidence indicating that cuing a specific portion of an object results in the entire object’s being attended to. In the present study, we examined whether previous experience with an object could halt perceptual (i.e., amodal) completion. In Experiment 1, two parallel rectangles were initially displayed, and then the middle portions of these objects were occluded. Attentional cuing effects were found for both discrete portions of the completed rectangles. In the final two experiments, four discrete objects were initially displayed, followed by the same occluder as that used in the first experiment. The appearance of the occluder (500 msec before the cue in Experiment 2, 100 msec before the cue in Experiment 3) allowed the four discrete objects to be completed into two rectangles. Attentional cuing effects were found for the completed rectangles in both experiments, indicating that previous experience was not sufficient to halt the amodal completion of objects.     

Scene context influences without scene gist: Eye movements guided by spatial associations in visual search

Although the use of semantic information about the world seems ubiquitous in every task we perform, it is not clear whether we rely on a scene’s semantic information to guide attention when searching for something in a specific scene context (e.g., keys in one’s living room). To address this question, we compared contribution of a scene’s semantic information (i.e., scene gist) versus learned spatial associations between objects and context. Using the flash-preview–moving-window paradigm Castelhano and Henderson (Journal of Experimental Psychology: Human Perception and Performance 33:753–763, 2007), participants searched for target objects that were placed in either consistent or inconsistent locations and were semantically consistent or inconsistent with the scene gist. The results showed that learned spatial associations were used to guide search even in inconsistent contexts, providing evidence that scene context can affect search performance without consistent scene gist information. We discuss the results in terms of hierarchical organization of top-down influences of scene context.