Roughness perception of unfamiliar dot pattern textures

Both vision and touch yield comparable results in terms of roughness estimation of familiar textures as was shown in earlier studies. To our knowledge, no research has been conducted on the effect of sensory familiarity with the stimulus material on roughness estimation of unfamiliar textures.The influence of sensory modality and familiarity on roughness perception of dot pattern textures was investigated in a series of five experiments. Participants estimated the roughness of textures varying in mean center-to-center dot spacing in experimental conditions providing visual, haptic and visual–haptic combined information.The findings indicate that roughness perception of unfamiliar dot pattern textures is well described by a bi-exponential function of inter-dot spacing, regardless of the sensory modality used. However, sensory modality appears to affect the maximum of the psychophysical roughness function, with visually perceived roughness peaking for a smaller inter-dot spacing than haptic roughness. We propose that this might be due to the better spatial acuity of the visual modality. Individuals appeared to use different visual roughness estimation strategies depending on their first sensory experience (visual vs. haptic) with the stimulus material, primarily in an experimental context which required the combination of visual and haptic information in a single bimodal roughness estimate. Furthermore, the similarity of findings in experimental settings using real and virtual visual textures indicates the suitability of the experimental setup for neuroimaging studies, creating a more direct link between behavioral and neuroimaging results.     

The influence on recognition of spoken words that are misperceived

Two experiments were performed that involved an initial word-identification task in which the acoustic signal was degraded by either 50% or 60% compression of the recorded words. A control group was tested at the original recording rate (0% compression). The compression manipulation was successful in increasing the number of identification errors. During the second stage of the experiments, words were read at a normal rate. In Experiment 1, the subjects indicated whether each word had appeared on the prior list, and in Experiment 2, the subjects estimated the number of times each word had been read on the prior list. The false-negative rate decreased and frequency ratings increased as a function of the number of prior presentations (one, two, or three) of the target words. The most interesting result was that the effect of repetitions was present even for words that had been misperceived.     

Alignment errors in Poggendorff-like displays when the variable segment is a dot,a dot series,or a line

In the standard Poggendorff figure, the abutting tip of the upper right transversal appears more misaligned than its distal tip. This appears paradoxical, since dot alignment errors increase with line-to-dot separation. To attempt a resolution of the paradox, four experiments were conducted in which single dots, series of dots, and lines were adjusted to be apparently collinear with a standard line segment, with neither, one, or both vertical inducing lines present. The results, taken together, suggested an explanation of the paradox and also that the standard Poggendorff display may result in alignment errors which represent a compromise judgment, based on conflicting cues to collinearity. In particular, the fourth experiment showed that line-to-line alignment errors could be made to resemble dot-to-line alignment errors by instructional variables. It was suggested that the effect was produced by forcing observers to process asymmetrically rather than symmetrically (Krantz & Weintraub, 1973).     

Concept learning,memory and transfer of dot pattern categories

In the first experiment, subjects rated the similarity of a sample of pairs of random dot patterns generated from 3 prototypes consisting of either 4, 6, or 9 dots. The results of the experiment tended to confirm the structure imposed on the patterns by the construction method. In the second experiment, subjects learned to classify random patterns generated from 2 prototypes with either short or long interprototype distance and consisting of either 4, 6, or 9 dots in a traditional concept identification task. After acquisition, memory for old and new distortions and the prototype, which was not presented during learning, was assessed. The tendency to call a pattern “new” increased with the distance between the pattern and its prototype. In a subsequent transfer test, all subjects saw patterns of either 4, 6, or 9 dots. Performance was above chance and the transfer from larger to smaller patterns tended to be greater than the transfer from smaller to larger patterns. This is consistent with a process of schema formation based on features common to most exemplars of the category. The results are discussed in relation to several theories of concept learning and schema abstraction.     

The logic of misperceived distance (or location) theories of the Poggendorff illusion

For the Poggendorff display (transversal interrupted by parallel lines), the typical distance-misperception theory postulates that a particular linear distance extending across the empty space between parallels is underestimated; examples are the intertransversal slant distance defined by the closest ends of the transversal segments (a “wings-in Müller-Lyer like” underestimation) or the perpendicular distance between parallels (parallels “attract”). Distance misperception by itself, however, can neither establish that perceived transversal misalignment exists for a Poggendorff display nor specify the perceivedlocation conditions) that will produce perceptual collinearity. The perceptual displacement vector is introduced as a means of specifying fully the perceptual mislocation (displacement) of one transversal segment with respect to the other. Given this vector information (direction as well as distance), the logical soundness of theories postulating distance or location misperception were evaluated, and they were compared on the basis of extant data. Such vector information can be used to evaluate other classes of theories as well.     

A dot that went for a walk: People prefer lines drawn with human-like kinematics

A dominant theory of embodied aesthetic experience (Freedberg & Gallese, 2007, Trends in Cognitive Sciences, 11, 197) posits that the appreciation of visual art is linked to the artist’s movements when creating the artwork, yet a direct link between the kinematics of drawing actions and the aesthetics of drawing outcomes has not been experimentally demonstrated. Across four experiments, we measured aesthetic responses of students from arts and non-arts backgrounds to drawing movements generated from computational models of human writing. Experiment 1 demonstrated that human-like drawing movements with bell-shaped velocity profiles (Sigma Lognormal [SL] and Minimum Jerk [MJ]) are perceived as more natural and pleasant than movements with a uniform profile, and in both Experiments 1 and 2 movements that were perceived as more natural were also preferred. Experiment 3 showed that this effect persists if lower-level dynamic stimulus features are fully matched across experimental and control conditions. Furthermore, aesthetic preference for human-like movements were associated with greater perceptual fluency in Experiment 3, evidenced by unbiased estimations of the duration of natural movements. In Experiment 4, line drawings with visual features consistent with the dynamics of natural, human-like movements were preferred, but only by art students. Our findings directly link the aesthetics of human action to the visual aesthetics of drawings, but highlight the importance of incorporating artistic expertise into embodied accounts of aesthetic experience.     

The optic trajectory is not a lot of use if you want to catch the ball

According to linear optic trajectory (LOT) theory, fielders use the direction of curvature of theoptic trajectory to control the way they run to intercept the ball. Data presented by D. M. Shaffer and M. K. McBeath (2002) as support for LOT theory show that the optic trajectory of balls that will fall behind the fielder provide the cue that LOT theory predicts would send the fielder running forward, not backward. In this article, the authors show that watching these balls would provide the fielder with the cue that the optic acceleration cancellation (OAC) theory of interception predicts would send the fielder running backward. It appears that the fielders studied by Shaffer and McBeath were following the cue predicted by OAC theory, not that predicted by LOT theory.     

The role of movement in perceptual adaptation to a tilted retinal image

Attention, Perception, & Psychophysics - Perceptual adaptation to prismatically created tilt of the retinal image was measured after three conditions of exposure: active, passive and no...     

Judgment of numerosity: effects of symmetry and goodness in dot pattern arrays

Studies of numerosity judgment characteristically use random dot arrays as targets. A few recent studies have shown concern for the role played by configural properties of the pattern array in the judgment of numerosity. The primary purpose of the present short report was to establish whether amount of whole symmetry and part symmetry in an array affects the accuracy of numerosity judgment. A subsidiary purpose was to explore the relationship between probability of correct judgment of numerosity and independent data on the immediate recallability of the same pattern arrays. Two hundred patterns with array sizes 1–11 and five amounts of whole and part symmetry were used. There were two clear findings. One, that the probability of correct numerosity judgment increases with amount of whole symmetry but not of part symmetry. Two, that such probability scores yield essentially zero correlations with two measures of pattern recallability and with a measure of pattern goodness. The findings are consistent with the arguments (a) that whole symmetry is rapidly abstracted at a very early stage and facilitates parallel processing of numerosity, and (b) that the numerosity of an array is assessed sooner than the spatial locations of the configuration per se can be encoded.     

The perceptual organization of dot lattices

Bravais (1850/1949) demonstrated that there are five types of periodic dot patterns (or lattices): oblique, rectangular, centered rectangular, square, and hexagonal. Gestalt psychologists studied grouping by proximity in rectangular and square dot patterns. In the first part of the present paper, I (1) describe the geometry of the five types of lattices, and (2) explain why, for the study of perception, centered rectangular lattices must be divided into two classes (centered rectangular andrhombic). I also show how all lattices can be located in a two-dimensional space. In the second part of the paper, I show how the geometry of these lattices determines their grouping and their multistability. I introduce the notion ofdegree of instability and explain how to order lattices from most stable to least stable (hexagonal). In the third part of the paper, I explore the effect of replacing the dots in a lattice with less symmetric motifs, thus creating wallpaper patterns. When a dot pattern is turned into a wallpaper pattern, its perceptual organization can be altered radically, overcoming grouping by proximity. I conclude the paper with an introduction to the implications of motif selection and placement for the perception of the ensuing patterns.     

The effect of a moving dot transversal on the Poggendorff illusion

In attempting to derive the minimal component of the Poggendorff figure which would still produce an illusion, responses to three types of transversal were measured. One was the customary solid line type; a second type presented the two segments sequentially, alternating between them; and the third consisted of a moving dot which traveled the transversal path. Each transversal was shown with and without verticals, for a total of six conditions. Ten subjects in each condition adjusted the luminous transversal until the segments appeared to be collinear. Figures with verticals present showed a greater magnitude of illusion than those without, and discrepancies for moving dot transversals were greater than those for comparable solid line figures. Since alternating transversals were not significantly larger than solid line figures, it was concluded that the magnitude of the moving dot effect could not be attributed to temporal sequence. An eyemovement hypothesis was suggested instead.     

The abstraction and generalization of dot patterns

The Ss were trained on patterns representing different levels of distortion and transferred to test trials containing the old training patterns, the prototype patterns, and new distortions. Training on low levels of distortion consistently produced superior performance on all test patterns except the most distorted ones. The results also showed that the prototypes and low distortion-level test patterns of meaningful concepts were identified more often than prototypes and low distortion-level test patterns of meaningless concepts but the reverse was true for highly distorted test patterns. Training with patterns whose average dot positions corresponded to the original positions of the dots in the prototypes and to two different levels of distortion of training patterns did not facilitate transfer of any abstractions formed.     

The trajectory of suicidal behavior over time

Some empirical work on genetic and prenatal factors in suicidality is presented. These factors may represent enduring predispositions that comprise risk for initial as well as later suicidal behavior. The existence of enduring predispositions does not preclude the possibility, however, that initial suicidal behavior sets processes into motion that spur later suicidal behavior. Based on past conceptual and empirical work, I suggest two psychological processes--cognitive sensitization and opponent processes--that may partly explain the link between past and future suicidal behavior.     

The trajectory of the target probability effect

The effect of target probability on detection times is well-established: Even when detection accuracy is high, lower probability targets are detected more slowly than higher probability ones. Although this target probability effect on detection times has been well-studied, one aspect of it has remained largely unexamined: How the effect develops over the span of an experiment. Here, we investigated this issue with two detection experiments that assessed different target probability ratios. Conventional block segment analysis and linear mixed-effects modeling converged on two key findings. First, we found that the magnitude of the target probability effect increases as one progresses through a block of trials. Second, we found, by examining the trajectories of the low- and high-probability targets, that this increase in effect magnitude was driven by the low-probability targets. Specifically, we found that low-probability targets were detected more slowly as a block of trials progressed. Performance to high-probability targets, on the other hand, was largely invariant across the block. The latter finding is of particular interest because it cannot be reconciled with accounts that propose that the target probability effect is driven by the high-probability targets.     

The perception of continuous curves in dot stimuli

Two categorisation experiments are reported in which the perceptual phenomenon that some simple arrays of discrete dots appear as a continuous curve whereas others are perceived as an angular contour or as consisting of separate groups of dots was investigated. Triplets of dots were presented in the first experiment, and complete or incomplete regular dot polygons (ie dots positioned on the vertices of imaginary regular polygons) in the second. In both experiments the perception of a curve versus an angle was determined mainly by the relative orientations of the dots, ie by the angles between successive virtual lines, whereas the lengths of the virtual lines had relatively little influence. In experiment 2 the number of displayed dots was shown to be a second independent factor for perceiving continuity. These results are in agreement with results from experiments on dipole textures discrimination, and suggest the psychological existence and importance of virtual lines in the visual processing of dot stimuli.     

Agrammatic Broca's aphasia is not associated with a single pattern of comprehension performance

One influential hypothesis posits that the brain regions implicated in Broca's aphasia are responsible for specific syntactic operations that are necessary for the comprehension and production of sentences (Grodzinsky, 1986, 1990, in press). The empirical basis of this hypothesis is the claim that Broca's aphasics have no difficulty understanding sentences in the active voice (and other "canonical" sentence types, such as subject relatives and clefts with negative predicates), but perform at chance level with passive voice constructions (and other "noncanonical" sentences such as object-gap relatives and object clefts). In the face of well-established results indicating that Broca's aphasics can exhibit several different performance patterns on these sentence types, Grodzinsky, Pi?ango, Zurif, and Drai (1999) argued that these conflicting results do not challenge the theory when the data are analyzed appropriately. They carried out a creative statistical analysis of the comprehension performance of published cases of Broca's aphasia and concluded that all of these cases are in agreement with the predicted pattern: chance on passives and 100% correct on actives. Here we show that the statistical reasoning adopted by Grodzinsky et al. (1999) is flawed. We also show that the comprehension performance of a substantial number of the Broca's aphasics in their own sample does not conform to the pattern required. Rather, contrary to these authors' claim, Broca's aphasia is not associated with a consistent pattern of sentence comprehension performance, but allows for a number of distinct patterns in different patients.