The nature of correlation perception in scatterplots

For scatterplots with gaussian distributions of dots, the perception of Pearson correlation r can be described by two simple laws: a linear one for discrimination, and a logarithmic one for perceived magnitude (Rensink & Baldridge, 2010). The underlying perceptual mechanisms, however, remain poorly understood. To cast light on these, four different distributions of datapoints were examined. The first had 100 points with equal variance in both dimensions. Consistent with earlier results, just noticeable difference (JND) was a linear function of the distance away from r = 1, and the magnitude of perceived correlation a logarithmic function of this quantity. In addition, these laws were linked, with the intercept of the JND line being the inverse of the bias in perceived magnitude. Three other conditions were also examined: a dot cloud with 25 points, a horizontal compression of the cloud, and a cloud with a uniform distribution of dots. Performance was found to be similar in all conditions. The generality and form of these laws suggest that what underlies correlation perception is not a geometric structure such as the shape of the dot cloud, but the shape of the probability distribution of the dots, likely inferred via a form of ensemble coding. It is suggested that this reflects the ability of observers to perceive the information entropy in an image, with this quantity used as a proxy for Pearson correlation.     

Heuristic method for label placement in scatterplots

Kuhfeld (1986) has proposed several alternative scatterplot routines with labeled points. To this list is added a heuristic routine that repositions labels to eliminate overlap while attempting to maximize the number of labels presented in a metric plot.I would like to thank the reviewer of a previous version of this paper for several excellent suggestions for future modifications of both the label positioning routine and the overall plotting package.     

The independence of size perception and distance perception

Research on distance perception has focused on environmental sources of information, which have been well documented; in contrast, size perception research has focused on familiarity or has relied on distance information. An analysis of these two parallel bodies of work reveals their lack of equivalence. Furthermore, definitions of familiarity need environmental grounding, specifically concerning the amount of size variation among different tokens of an object. To demonstrate the independence of size and distance perception, subjects in two experiments were asked to estimate the sizes of common objects from memory and then to estimate both the sizes and the distances of a subset of such objects displayed in front of them. The experiments found that token variation was a critical variable in the accuracy of size estimations, whether from memory or with vision, and that distance had no impact at all on size perception. Furthermore, when distance information was good, size had no effect on distance estimation; in contrast, at far distances, the distances to token variable or unknown objects were estimated with less accuracy. The results suggest that size perception has been misconceptualized, so that the relevant research to understand its properties has not been undertaken. The size-distance invariance hypothesis was shown to be inadequate for both areas of research.     

The independence of size perception and distance perception.

Research on distance perception has focused on environmental sources of information, which have been well documented; in contrast, size perception research has focused on familiarity or has relied on distance information. An analysis of these two parallel bodies of work reveals their lack of equivalence. Furthermore, definitions of familiarity need environmental grounding, specifically concerning the amount of size variation among different tokens of an object. To demonstrate the independence of size and distance perception, subjects in two experiments were asked to estimate the sizes of common objects from memory and then to estimate both the sizes and the distances of a subset of such objects displayed in front of them. The experiments found that token variation was a critical variable in the accuracy of size estimations, whether from memory or with vision, and that distance had no impact at all on size perception. Furthermore, when distance information was good, size had no effect on distance estimation; in contrast, at far distances, the distances to token variable or unknown objects were estimated with less accuracy. The results suggest that size perception has been misconceptualized, so that the relevant research to understand its properties has not been undertaken. The size-distance invariance hypothesis was shown to be inadequate for both areas of research.     

The perception of time

The present paper organizes and evaluates selected portions of the time perception literature. Emphasis is on data and theory concerned primarily with judgments of brief temporal intervals. Research concerning the psychophysical law for time, Weber’s law, the time-order error, and the role of nontemporal information is evaluated. This is followed by a consideration of current, quantitatively oriented, theoretical formulations for time perception.     

The two sides of perception

by Richard B. Ivry and Lynn C. Robertson, MIT Press, 1998. $55.00 (315 pages) ISBN 0 262 09034 1.     

The perception of alternated speech

When speech is rapidly alternated between the two ears, intelligibility declines as rates approach 3–5 switching cycles/sec and then paradoxically returns to a good level beyond that point. The present study examines previous explanations of the phenomenon by comparing intelligibility of alternated speech with that for presentation of an interrupted message to a single ear. Results favor one of two possible explanations, and a theoretical model to account for the effect is proposed.     

婴儿的痛觉

婴儿痛觉对婴儿的生长发育有重要意义, 已经日益引发研究者的兴趣。痛觉本质上是一种不愉悦的感官和情绪体验, 是通过早年与伤害有关的经历习得的。在心理学角度, 在介绍婴儿痛觉概念、神经生理机制、评估工具的基础上, 系统梳理痛觉对婴儿生长发育的影响及其影响因素十分必要。后续研究需继续完善婴儿痛觉的测量方法, 考察疼痛反应在不同文化和不同群体间的差异。     

The visual perception of velocity

Summary In this section it is concluded that velocity is perceived directly and is dynamically conditioned by the structure and general properties of the visual field in which the movement occurs. The visual perception of velocity follows dynamic laws that are not immediately deducible from the velocity of the stimulus as physically defined. No physiological theory is offered but it is pointed out that the theory of physiological Gestalten is essentially correct in its basic assumptions concerning the perception of movement.The investigation has bearing on the problems of movement thresholds, movement after-images and the perception of time.This paper is abridged from a thesis presented to the faculty of the graduate school of Yale University in partial fulfilment of the requirements for the degree of Doctor of Philosophy. The study was started in the Psychological Institute of the University of Berlin in 1926–1927 and completed at Yale University in 1928–1929. The work at Berlin, which has been already reported [cf. J. F. Brown, Über gesehene Geschwindigkeit. Psychol. Forschg 10, 84–101 (1927)] was largely exploratory in nature; that at Yale was undertaken to fill the gaps in the experimental series and to control more completely the causal factors. For clarity of exposition the previously reported data are included here so far as necessary. The writer is indebted to Professor W. Köhler of the University of Berlin for suggesting the problem, and to Professors R. P. Angier, R. Dodge, and L. T. Spencer of Yale University for many valuable suggestions. He wishes also to express his thanks to the subjects who served in the experiments.     

The haptic perception of curvature

Ninety-two subjects, schoolchildren and undergraduate and postgraduate students, took part in a series of experiments on the haptic perception of curvature. A graded series of surfaces was produced using piano-convex lenses masked off to produce curved strips that could be explored without using arm movements. Thresholds were measured using the constant method and a staircase procedure. Experiments 1 and 2 yielded data on the absolute and difference thresholds for curvature. Experiment 3 demonstrated that the effective stimulus for curvature is represented by the overall gradient of a curved surface. Using this measure, it was shown that the present absolute thresholds for curvature are lower than those previously reported. In Experiment 4, absolute thresholds were compared using spherical and cylindrical curves: the results showed that, at least with the narrow strips used, the type of curvature does not exert a significant influence on performance. In Experiment 5, the subjective response to curvature was assessed using a rating procedure. Power functions are reported, although the relationship between stimuli and responses had a strong linear component. This suggests that haptically perceived curvature may be a metathetic rather than a prothetic continuum.     

The perception of sex-inconsistent behavior

Sex-role perceptions were approached from an out-of-role attributional framework, with the predictions that out-of-role behavior would be rated more extreme than in-role behavior on sex-role stereotype scales and that out-of-role behavior would be seen as more internally determined. One hundred and twenty male and female college students heard one of four tapes in which the two stimulus persons (SPs), male and female, behaved in sex-role consistent or inconsistent behavior using the dimension of dominance-submission (DM-DF, SM-SF, DM-SF, DF-SM). The DF, compared to the DM, was attributed more masculinity and less femininity. The DF's behavior, compared to the DM, was seen as originating more from internal than situational causes.     

The obscure act of perception

Finding disjunctivist versions of direct realism unexplanatory, Mark Johnston [(2004). Philosophical Studies, 120, 113–183] offers a non-disjunctive version of direct realism in its place and gives a defense of this view from the problem of hallucination. I will attempt to clarify the view that he presents and then argue that, once clarified, it either does not escape the problem of hallucination or does not look much like direct realism.