Effects of binding in the identification of objects

The binding problem requires a solution at the level of individual neurons, but no definite mechanism has yet be given. Therefore, the neuronal level is as yet inadequate for modeling cognitive processes in which binding plays a crucial role. Moreover, the neuronal level involves too many details that are unlikely to be essential for understanding cognition. A general model of cognitive brain functioning is described in which cognitive tasks are represented in a network of cell assemblies. In the network, binding is functionally defined in a way that is compatible with the neuronal level. A computer simulation of the model clarifies how the binding of location and identity of a set of simultaneously presented letters takes place and how questions about the location and identity of the letters are answered. From the simulation of the task three predictions on the logistics of neural processes are derived: 1. When the cell assembly representing a letter participates in more than one temporary excitation loop, it will reach its critical threshold faster. At the behavioral level this means that as the number of identical letters in the display increases, responses will be faster. 2. In order to answer questions about the location and identity of presented letters cell assemblies representing the target location and the target identity have to become bound to their appropriate values. As a consequence the facilitatory effect of identical letters will be stronger if they involve the target location or the target identity than when identical non-targets are involved. 3. Negative identifications are more dependent on the presentation time of the letters than positive identifications because the excitation loops involved take more time to reach the critical threshold. Therefore, the facilitatory effect of identical letters is stronger when the external activation is relatively strong, i.e., when presentation time of the letters is sufficiently long. The reaction times obtained in three behavioral experiments support these hypotheses. Effects of binding can therefore be predicted on the basis of the general logistics of neural processes, without assumptions about a specific binding mechanism at the neuronal level.     

Effects of vision and haptics on categorizing common objects

Most research on object recognition and categorization centers on vision. However, these phenomena are likely influenced by the commonly used modality of touch. The present study tested this notion by having participants explore three-dimensional objects using vision and haptics in naming and sorting tasks. Results showed greater difficulty naming (recognizing) and sorting (categorizing) objects haptically. For both conditions, error increased from the concrete attribute of size to the more abstract quality of predation, providing behavioral evidence for shared object representation in vision and haptics.     

Haptic identification of common objects: effects of constraining the manual exploration process

In this article, we address the effects on haptic recognition of common objects when manual exploration is constrained by using two kinds of rigid links--sheaths (Experiment 1A) and probes (Experiments 1B and 2). The collective effects of five different constraints are considered, including three from previous research (i.e., reducing the number of end effectors, wearing a compliant finger cover, and splinting the fingers; Klatzky, Loomis, Lederman, Wake, & Fujita, 1993) and from two current constraints (i.e., wearing a rigid finger sheath and using a rigid probe). The resulting impairments are interpreted in terms of the loss of somatosensory information from cutaneous and/or kinesthetic inputs. In addition, we relate the results to the design of haptic interfaces for teleoperation and virtual environments, which share some of the same reduction of sensory cues that we have produced experimentally.     

Effects of stimulus duration and inter-letter spacing on letter-in-string identification

Effects of stimulus duration and inter-letter spacing were studied in a letter-in-string identification paradigm. Participants were shown strings of 5 random consonants (e.g., PGKDM) centered on fixation and were asked to identify the letter that had appeared at a post-cued location. Stimulus duration was manipulated in Experiment 1 (13 ms–91 ms), and inter-letter spacing manipulated in Experiment 2 (for a fixed stimulus duration of 26 ms). We contrasted performance to outer-letters (positions 1 and 5) with non-central inner letters (positions 2 and 4), the first-letter (position 1) with the final letter (position 5), and the central-letter (position 3) with the other inner letters (positions 2 and 4). The outer-letter advantage and the first-letter advantage were present throughout the entire range of exposure durations, whereas the central-letter advantage increased with longer exposures. On the other hand, increased spacing reduced both the outer-letter advantage and the first-letter advantage, whereas it led to a greater central-letter advantage. Changes in acuity and crowding as a function of stimulus exposure and inter-letter spacing, can account for this pattern of results.     

Functional significance of stimulus orientation: effects on orientation discrimination.

Children (6- and 9-year-olds) and adults were required to discriminate identical pairs of visual stimuli from mirror images. It was hypothesized that a key factor in performance would be the extent to which orientation was a functionally significant attribute of the stimuli. Two variables were manipulated, type of orientation discrimination and stimulus class. The first variable refers to the fact that the mirror images could be produced by either left/right or top/bottom reversals. Three classes of stimuli, varying in the extent to which a particular orientation was emphasized, were used: mobile objects (for which left/right orientation is assumed to be important); stationary objects (which lack comparable relevance for left/right orientation); and novel, abstract forms. The prediction was that if the discrimination task involved left/right reversals, as contrasted with top/bottom reversals, subjects would show an advantage for mobile objects, producing an interaction between stimulus class and orientation discrimination. In the first study, the subjects were children and performance was measured in terms of error rates. In the second study adults were tested, and reaction times were measured. Both studies manifested the predicted interaction. Results are discussed in terms of an information-processing framework, in which the incorporation of orientation-related features in the code representing a stimulus varies with the functional significance of the orientation to the stimulus class.     

Effects of the orientation of moving objects on the perception of streaming/bouncing motion displays

In this study, we examined the contribution of the orientation of moving objects to perception of a streaming/bouncing motion display. In three experiments, participants reported which of the two types of motion, streaming or bouncing, they perceived. The following independent variables were used: orientation differences between Gabor micropatterns (Gabors) and their path of motion (all the experiments) and the presence/absence of a transient tone (Experiment 1), transient visual flash (Experiment 2), or concurrent secondary task (Experiment 3) at the coincidence of Gabors. The results showed that the events at coincidence generally biased responses toward the perception of bouncing. On the other hand, alignment of Gabors with their motion axes significantly reduced the frequency of bounce perception. The results also indicated that an object whose orientation was parallel to its motion path strengthened the spatiotemporal integration of local motion signals along a straight motion path, resulting in the perception of streaming. We suggest that the effect of collinearity between Gabors and their motion path is relatively free from the effect of attention distraction.     

Identification of symmetry: Effects of stimulus orientation and head position

It has been argued that the perceptual advantage of symmetry depends upon the essentially symmetrical properties of the visual system. According to this explanation, the ease of identification of symmetries about different axes of orientation should decrease with increasing distance from the vertical: Reaction times to vertical symmetry should be faster than those to diagonal symmetry, which in turn should be faster than those to horizontal symmetry. Previous research demonstrating this pattern of responding employed stimuli with linear axes. In the present study, the subjects viewed tachistoscopically presented symmetrical and asymmetrical dot patterns (which had no explicit axes) in one of three head positions: upright, 45 deg left, and 45 deg right. The subjects’ performance failed to support the structural explanation: Identification of symmetry is equivalently fast for vertical and horizontal; vertical and horizontal show strong advantages over obliques, and this general advantage follows retinal coordinates. Findings are discussed in light of alternative theories of symmetry processing.     

Determining the orientation of depth-rotated familiar objects

How does the human visual system determine the depth-orientation of familiar objects? We examined reaction times and errors in the detection of 15° differences in the depth orientations of two simultaneously presented familiar objects, which were the same objects (Experiment 1) or different objects (Experiment 2). Detection of orientation differences was best for 0° (front) and 180° (back), while 45° and 135° yielded poorer results, and 90° (side) showed intermediate results, suggesting that the visual system is tuned for front, side and back orientations. We further found that those advantages are due to orientation-specific features such as horizontal linear contours and symmetry, since the 90° advantage was absent for objects with curvilinear contours, and asymmetric object diminished the 0° and 180° advantages. We conclude that the efficiency of visually determining object orientation is highly orientation-dependent, and object orientation may be perceived in favor of front-back axes.     

Visually guided grasping of common objects: Effects of priming

Priming effects were tested on the planning of the grasping of common objects under full vision during action performance. Healthy participants took part in four experiments which manipulated the nature of the prime (objects, circular block, rectangular bar) and priming context (blocked vs. mixed). Each experiment relied on four priming conditions: (1) congruent orientation, (2) incongruent orientation, (3) neutral prime, and (4) no prime. Priming was observed to have a facilitating effect on visually guided grasping when the object to be grasped was primed by a congruently oriented identical object. This effect was rather independent of the priming context (experimental set-up). Our data suggest an object's functional identity may contribute to the priming effect, as well as its intrinsic (e.g., shape, size) and extrinsic (orientation) visual characteristics. We showed that the planning of visually guided grasping is influenced by prior visual experience, and thus that grasping is not based exclusively on real-time processing of visual information.     

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.     

Multidimensional stimulus identification

In an absolute judgment task, total information transmitted about a set of stimuli increases as the dimensionality of the stimuli is increased. However, as the number of dimensions is increased, information transmitted about each component dimension decreases. Four factors were proposed that might, singly or in combination, account for this decrement: stimulus duration, interdimensional interference, distraction, and response complexity. The results of four experiments established that each of these factors may be operative under appropriate circumstances. It was also concluded that component dimensions were processed simultaneously rather than sequentially. However, the processing was not truly parallel because the input channels were not independent of one another.     

Category-specific effects on the identification of non-manipulable objects

Theories of category-specific effects on visual object identification predict easier identification of non-living than living objects. The Sensory-Functional theory credits greater representational weighting of the visual properties of living objects independent of greater weighting of the functional properties of non-living objects. It predicts a lost or reversed non-living advantage for non-manipulable objects. Normal participants matched pictures of non-manipulable objects with words describing three levels of identity while visual object similarity, and concept familiarity were controlled. Consistent with the Sensory-Functional theory, living objects were matched faster than non-living objects. Concept familiarity facilitated subordinate matches. Visual similarity hampered subordinate matches and facilitated basic matches.     

Regulatory fit effects on stimulus identification

This article examines the effects of a fit between a person's global regulatory focus and the local task reward structure on perceptual processing and judgment. On each trial, participants were presented with one of two briefly presented stimuli and were asked to identify it. Participants were placed in a promotion focus (a situationally induced sensitivity to gains) or a prevention focus (a situationally induced sensitivity to losses) and were asked to maximize gains or minimize losses. An asymmetric payoff ratio biased the overall reward toward one identification response over the other. Two experiments tested the role of regulatory fit when internal familiarity and perceptual sensitivity were low or high. When familiarity and sensitivity were low, participants in a regulatory fit (promotion focus with gains or a prevention focus with losses) showed greater perceptual sensitivity but no response bias differences, relative to participants in a regulatory mismatch. When familiarity and sensitivity were high, participants in a regulatory fit showed a response bias toward the high-payoff stimulus but no differences in perceptual sensitivity. Speculations are offered on the neurobiological basis of this effect, as well as implications of this work for clinical disorders such as depression.     

The effects of contextual scenes on the identification of objects

Memory & Cognition - This experiment demonstrates the influence of the prior presentation of visual scenes on the identification of briefly presented drawings of real-world objects. Different...