A plea for logical objects

An account of validity that makes what is invalid conditional on how many individuals there are is what I call a conditional account of validity. Here I defend conditional accounts against a criticism derived from Etchemendy’s well-known criticism of the model-theoretic analysis of validity. The criticism is essentially that knowledge of the size of the universe is non-logical and so by making knowledge of the extension of validity depend on knowledge of how many individuals there are, conditional accounts fail to reflect that the former knowledge is basic, i.e., independent of knowledge derived from other sciences. Appealing to Russell’s pre-Principia logic, I defend conditional accounts against this criticism by sketching a rationale for thinking that there are infinitely many logical objects.     

Infants' formation and use of categories to segregate objects

Four- and-a-half-month-old infants' (N = 100) category formation and use was studied in a series of five experiments. For each experiment, the test events featured a display composed of a cylinder and a box. Previous research showed that this display is not clearly parsed as a single unit or as two separate units by infants of this age. Immediately prior to testing, infants were shown a set of category exemplars. Knowledge about this category could help infants disambiguate the test display, which contained a novel exemplar of this category. Clear interpretation of the test display as composed of two separate units (as indicated by infants' longer looking at the move-together than at the move-apart test event) was taken as evidence of category formation and use. In Experiments 1 and 5, infants' prior experience with a set of three different boxes that were similar to the test box facilitated their segregation of the test display. Experiment 2 showed that three different exemplars are necessary: prior experience with any two of the three boxes used in Experiment 1 did not facilitate infants' segregation of the test display. Experiment 3 showed that variability in the exemplar set is necessary: prior experience with three identical boxes did not facilitate infants' segregation of the test display. Experiment 4 showed that under these conditions of very brief prior exposure, similarity between the exemplar set and test box is necessary: prior experience with three different boxes that were not very similar to the test box did not facilitate infants' segregation of the test display. Together, these findings suggest that: (a) number of exemplars, variability, and similarity in the exemplar set are important for infants' category formation, and (b) infants use their category knowledge to determine the boundaries of the objects in a display.     

The Logical Basis of the Tractarian Ontology

This paper focuses on the relation between logic and ontology. In particular, it demonstrates how classical logical theory can clarify the ontological part of Ludwig Wittgenstein’s Tractatus Logico-Philosophicus. To this end, the work examines the adequacy of a formal system that was devised by the Polish logician, mathematician and philosopher Roman Suszko (1919–1979) as a model for the Tractatus. Following a brief explanation of the Tractarian ontology, the main ideas of Suszko’s system and its philosophical significance will be considered. The latter will be illustrated in the context of central Tractarian concepts. Finally, two implications for a better understanding of the Tractarian ontology will be pointed out.

Visual working memory capacity for objects from different categories: a face-specific maintenance effect

The capacity of visual working memory was examined when complex objects from different categories were remembered. Previous studies have not examined how visual similarity affects object memory, though it has long been known that similar-sounding phonological information interferes with rehearsal in auditory working memory. Here, experiments required memory for two or four objects. Memory capacity was compared between remembering four objects from a single object category to remembering four objects from two different categories. Two-category sets led to increased memory capacity only when upright faces were included. Capacity for face-only sets never exceeded their nonface counterparts, and the advantage for two-category sets when faces were one of the categories disappeared when inverted faces were used. These results suggest that two-category sets which include faces are advantaged in working memory but that faces alone do not lead to a memory capacity advantage.     

Using logical relevance for question answering

We propose a novel method of determining the appropriateness of an answer to a question through a proof of logical relevance rather than a logical proof of truth. We define logical relevance as the idea that answers should not be considered as absolutely true or false in relation to a question, but should be considered true more flexibly in a sliding scale of aptness. This enables us to reason rigorously about the appropriateness of an answer even in cases where the sources we are getting answers from are incomplete or inconsistent or contain errors. We show how logical relevance can be implemented through the use of measured simplification, a form of constraint relaxation, in order to seek a logical proof than an answer is in fact an answer to a particular question. We then give an example of such an implementation providing a set of specific rules for this purpose.     

Apes know that hidden objects can affect the orientation of other objects

Four bonobos, seven gorillas, and six orangutans were presented with two small rectangular boards on a platform. One of the boards had a piece of food under it so that it acquired an inclined orientation whereas the other remained flat on the platform. Subjects preferentially selected the inclined board. In another experiment, subjects were initially presented with two inclined boards and a transformation took place in which one of the boards fell flat to the platform while the other remained inclined. Subjects also preferred the board that remained inclined. Two additional experiments highlighted some of the possible limitations of their reasoning in this task. Presented with two inclined boards, one of which was visibly supported by a piece of wood, they failed to systematically select the unsupported one whose only reason for being inclined was the presence of the reward. Another experiment presented two rewards in each trial (instead of the customary one) in one of the following two combinations: large banana vs. small carrot or small banana vs. large carrot. Prior to the test, E presented both rewards to the subject and then hid each of them under one of the boards so that both boards were differentially inclined due to the different sizes of the rewards involved. Although subjects selected the board that showed a greater inclination (thus securing the larger reward), they disregarded the type of food that was involved. This often meant that they chose the large carrot over the small banana even though they reversed such a choice when the rewards were not occluded by the boards. Providing subjects with a 'reminder' of the type of reward hidden under the boards did not alter the original results. There was no evidence of learning throughout the various experiments and control tests ruled out the possibility of inadvertent cuing by the experimenter, poor performance due to a lack of motivation, or good performance due to a predisposition to select objects with sloped surfaces. It is concluded that subjects made some inferences about the reason for the inclined orientation of the boards, and not simply associated an inclined orientation with the presence of the reward.     

Basic objects in natural categories

Categorizations which humans make of the concrete world are not arbitrary but highly determined. In taxonomies of concrete objects, there is one level of abstraction at which the most basic category cuts are made. Basic categories are those which carry the most information, possess the highest category cue validity, and are, thus, the most differentiated from one another. The four experiments of Part I define basic objects by demonstrating that in taxonomies of common concrete nouns in English based on class inclusion, basic objects are the most inclusive categories whose members: (a) possess significant numbers of attributes in common, (b) have motor programs which are similar to one another, (c) have similar shapes, and (d) can be identified from averaged shapes of members of the class. The eight experiments of Part II explore implications of the structure of categories. Basic objects are shown to be the most inclusive categories for which a concrete image of the category as a whole can be formed, to be the first categorizations made during perception of the environment, to be the earliest categories sorted and earliest named by children, and to be the categories most codable, most coded, and most necessary in language.     

Object manipulation facilitates kind-based object individuation of shape-similar objects

Five experiments investigated the importance of shape and object manipulation when 12-month-olds were given the task of individuating objects representing exemplars of kinds in an event-mapping design. In Experiments 1 and 2, results of the study from Xu, Carey, and Quint (2004, Experiment 4) were partially replicated, showing that infants were able to individuate two natural-looking exemplars from different categories, but not two exemplars from the same category. In Experiment 3, infants failed to individuate two shape-similar exemplars (from Pauen, 2002a) from different categories. However, Experiment 4 revealed that allowing infants to manipulate objects shortly before the individuation task enabled them to individuate shape-similar objects from different categories. In Experiment 5, allowing object manipulation did not induce infants to individuate natural-looking objects from the same category. These findings suggest that object manipulation facilitates kind-based individuation of shape-similar objects by 12-month-olds.     

Detecting objects is easier than categorizing them

Two experiments compared performance in an object detection task, in which participants categorized photographs as objects and nonobject textures, and an object categorization task, in which photographs were categorized into basic-level categories. The basic-level categorization task was either easy (e.g., dogs vs. buses) or difficult (e.g., dogs vs. cats). Participants performed similarly in the detection and the easy-categorization tasks, but response times to the difficult-categorization task were slower. This latter finding is difficult to reconcile with the conclusions of Grill-Spector and Kanwisher (2005) who reported equivalent performance on detection and basic-level categorization tasks and took this as evidence that figure-ground segregation and basic-level categorization are mediated by the same mechanism.     

Detecting objects is easier than categorizing them

Two experiments compared performance in an object detection task, in which participants categorized photographs as objects and nonobject textures, and an object categorization task, in which photographs were categorized into basic-level categories. The basic-level categorization task was either easy (e.g., dogs vs. buses) or difficult (e.g., dogs vs. cats). Participants performed similarly in the detection and the easy-categorization tasks, but response times to the difficult-categorization task were slower. This latter finding is difficult to reconcile with the conclusions of Grill-Spector and Kanwisher (2005) Grill-Spector, G. and Kanwisher, N. 2005. Visual recognition: As soon as you know it is there, you know what it is. Psychological Science, 16: 152–160. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar] who reported equivalent performance on detection and basic-level categorization tasks and took this as evidence that figure–ground segregation and basic-level categorization are mediated by the same mechanism.     

The use of stories as autistic objects

This paper reviews Frances Tustin's concept of the 'autistic object' and its development over the course of her writings. Clinical material from work with a 4-year-old boy is brought to suggest that the concept can usefully be extended to include such cultural artefacts as stories as well as the physical objects emphasized by Tustin. It is also emphasized that the awareness of reality which autistic objects are used to defend against refers both to internal as well as external reality. The paper argues that it is the function to which the object is put that is critical in determining whether or not it should be viewed as an autistic object.     

Infants' representations of three-dimensional occluded objects

Infants' ability to represent objects has received significant attention from the developmental research community. With the advent of eye-tracking technology, detailed analysis of infants' looking patterns during object occlusion have revealed much about the nature of infants' representations. The current study continues this research by analyzing infants' looking patterns in a novel manner and by comparing infants' looking at a simple display in which a single three-dimensional (3D) object moves along a continuous trajectory to a more complex display in which two 3D objects undergo trajectories that are interrupted behind an occluder. Six-month-old infants saw an occlusion sequence in which a ball moved along a linear path, disappeared behind a rectangular screen, and then a ball (ball-ball event) or a box (ball-box event) emerged at the other edge. An eye-tracking system recorded infants' eye-movements during the event sequence. Results from examination of infants' attention to the occluder indicate that during the occlusion interval infants looked longer to the side of the occluder behind which the moving occluded object was located, shifting gaze from one side of the occluder to the other as the object(s) moved behind the screen. Furthermore, when events included two objects, infants attended to the spatiotemporal coordinates of the objects longer than when a single object was involved. These results provide clear evidence that infants' visual tracking is different in response to a one-object display than to a two-object display. Furthermore, this finding suggests that infants may require more focused attention to the hidden position of objects in more complex multiple-object displays and provides additional evidence that infants represent the spatial location of moving occluded objects.     

Categorical perception of familiar objects

We report three experiments where the categorical perception of familiar, three-dimensional objects was investigated. A continuum of shape change between 15 pairs of objects was created and the images along the continuum were used as stimuli. In Experiment 1 participants were first required to discriminate pairs of images of objects that lay along the shape continuum. Then participants were asked to classify each morph-image into one of two pre-specified classes. We found evidence for categorical perception in some but not all of our object pairs. In Experiment 2 we varied the viewpoint of the objects in the discrimination task and found that effects of categorical perception generalized across changes in view. In Experiment 3 similarity ratings for each object pair were collected. These similarity scores correlated with the degree of perceptual categorization found for the object pairs. Our findings suggest that some familiar objects are perceived categorically and that categorical perception is closely tied to inter-object perceptual similarity.     

Preschoolers search for hidden objects

The issue of whether young children use spatio-temporal information (e.g., movement of objects through time and space) and/or contact-mechanical information (e.g., interaction between objects) to search for a hidden object was investigated. To determine whether one cue can have priority over the other, a dynamic event that put these cues into conflict was created, with only spatio-temporal information being valid. The 3-year-olds used in the study were found to use the valid spatio-temporal cue exclusively and seemed to ignore the contact-mechanical cue. Both search behavior and eye tracking during the event support the view of a sophisticated sensitivity to the validity of a cue in indicating a target’s hidden location.     

Visual working memory for dynamic objects: Impaired binding between object feature and location

In daily life, people frequently need to observe dynamic objects and temporarily maintain their representations in visual working memory (VWM). The present study explored the mechanism underlying the binding between perceptual features and locations of dynamic objects in VWM. In three experiments, we measured and compared the memory performance for feature-location binding of multiple dynamic and static objects. The results showed that the feature-location binding was impaired for the dynamic objects compared with the static objects. The impairment persisted when the global spatial configuration of the objects remained intact during the motion, as well as when the binding task was relatively easy, such as binding between single-feature objects and coarse locations. The results indicate that object features and locations are not maintained in VWM as well-integrated object files; rather, the formation of feature-location binding may require additional processes, which are disrupted by the constant change of locations in dynamic circumstances. We propose a consolidation process as possible underlying mechanism, and discuss factors that may influence the strength of feature-location binding in dynamic circumstances.     

Individuation of visual objects over time

How does an observer decide that a particular object viewed at one time is actually the same object as one viewed at a different time? We explored this question using an experimental task in which an observer views two objects as they simultaneously approach an occluder, disappear behind the occluder, and re-emerge from behind the occluder, having switched paths. In this situation the observer either sees both objects continue straight behind the occluder (called "streaming") or sees them collide with each other and switch directions ("bouncing"). This task has been studied in the literature on motion perception, where interest has centered on manipulating spatiotemporal aspects of the motion paths (e.g. velocity, acceleration). Here we instead focus on featural properties (size, luminance, and shape) of the objects. We studied the way degrees and types of featural dissimilarity between the two objects influence the percept of bouncing vs. streaming. When there is no featural difference, the preference for straight motion paths dominates, and streaming is usually seen. But when featural differences increase, the preponderance of bounce responses increases. That is, subjects prefer the motion trajectory in which each continuously existing individual object trajectory contains minimal featural change. Under this model, the data reveal in detail exactly what magnitudes of each type of featural change subjects implicitly regard as reasonably consistent with a continuously existing object. This suggests a simple mathematical definition of "individual object:" an object is a path through feature-trajectory space that minimizes feature change, or, more succinctly, an object is a geodesic in Mahalanobis feature space.     

Infants' ability to use luminance information to individuate objects

Recent research indicates that infants first use form and then surface features as the basis for individuating objects. However, very little is known about the underlying basis for infants' differential sensitivity to form than surface features. The present research assessed infants' sensitivity to luminance differences. Like other surface properties, luminance information typically reveals little about an object. Unlike other surface properties (e.g. pattern, color), the visual system can detect luminance differences at birth. The outcome of two experiments indicated that 11.5-month-olds, but not 7.5-month-olds, used luminance differences to individuate objects. These results suggest that it is not the age at which infants can detect a feature, but the nature of the information carried by the feature, that determines infants' capacity to individuate objects.     

Optimal and preferred eye landing positions in objects and scenes

Viewing position effects are commonly observed in reading, but they have only rarely been investigated in object perception or in the realistic context of a natural scene. In two experiments, we explored where people fixate within photorealistic objects and the effects of this landing position on recognition and subsequent eye movements. The results demonstrate an optimal viewing position—objects are processed more quickly when fixation is in the centre of the object. Viewers also prefer to saccade to the centre of objects within a natural scene, even when making a large saccade. A central landing position is associated with an increased likelihood of making a refixation, a result that differs from previous reports and suggests that multiple fixations within objects, within scenes, occur for a range of reasons. These results suggest that eye movements within scenes are systematic and are made with reference to an early parsing of the scene into constituent objects.     

A direct comparison of infants' use of featural and spatiotemporal information when individuating objects in a non-occlusion event-monitoring design

A central issue within the field of object individuation concerns the kind of information that infants rely on when they succeed in individuating objects. By means of the violation-of-expectation strategy, the present study reports a comparison of 8.0- and 6.5-month-old infants' use of featural and spatiotemporal information in a new non-occlusion event-monitoring design. Using a mirror setup the memory demands were minimized, because all apparent changes in the unexpected test events took place in full view of the infants. The results indicate that the 8.0- and 6.5-month-old infants individuated objects successfully regardless of whether they were provided with featural or spatiotemporal information. The results are discussed in relation to the relevant literature.