Olga Eizner Favreau

Color and luminance share a common motion pathway.

Following exposure to a moving grating of bars differing only in luminance, a motion aftereffect (MAE) is observed on a stationary grating of bars differing only in chrominance. This suggests that the motion of equiluminous chromatic stimuli is sensed by a channel that responds to both luminance and chrominance and not by a separate channel specialized for the motion of colored stimuli. However, adding color to a low contrast luminance stimulus actually reduces its effectiveness at creating or nulling a MAE, indicating that the response of the motion pathway to color is qualitively different from its response to luminance. In addition, a chromatic stimulus demonstrates a dissociation between perceived speed, MAE speed and speed required to null the MAE that is absent for a luminance stimulus.

Perception of Motion in Equiluminous Kinematograms

Two fields of random dots that were identical except for a slight shift in a central square region were presented in rapid alternation. This produced a vivid impression of a square moving back and forth above the background. When the kinematogram is presented in equiluminous red/green, the motion of the central region can still be seen, although over a narrower range of alternation rates, interstimulus intervals, and displacements than for black/white presentation. The perception of motion for equiluminous stimuli indicates that colour and motion can be analyzed conjointly by the visual system. However, as originally reported by Ramachandran and Gregory, the segregation of the oscillating central square from the background is lost at equiluminance. This segregation process therefore appears to be colour-blind.

Independent orientation-selective mechanisms for the cardinal directions of colour space

Simultaneous, oppositely tilted, aftereffects were obtained for pairs of equiluminant gratings (e.g. magenta/cyan vs purple/greenish-yellow) and pairs of equiluminant and luminant gratings (e.g. magenta/cyan vs dark-grey/light-grey, or purple/greenish-yellow vs dark-grey/light-grey). Maximum aftereffects occurred for gratings whose colours were modulated along the principle axes of the colour space of Krauskopf, Williams and Heeley (1982): an axis of short-wavelength cone activation (B-cone axis), the difference between long- and medium-wavelength cone activation (R-G cone axis), and an axis of a contrast ratio of long-, medium- and short-wavelength cone activation (R + G + B cone axis). The results indicate that selectivity for orientation occurs independently in at least two chromatic channels and one achromatic channel.

Motion aftereffect: a global mechanism for the perception of rotation.

Observers adapted to motion by looking at rotating logarithmic spirals. They were tested with a stationary mirror image of the adapting spiral in which all contours were at 90° to those of the first spiral. Motion aftereffects were reported in the contrarotational direction—that is, observers who had seen clockwise rotating motion reported seeing counterclockwise aftereffects. These aftereffects lasted one-third as long as the aftereffects obtained when the adapting spiral was used as the test figure. These two aftereffects were shown to have different storage properties, thereby indexing the operation of at least two different mechanisms. We interpret the motion aftereffect that is obtained with the mirror-image stimulus as indicative of the existence of global rotation detectors.

Motion aftereffects: Evidence for parallel processing in motion perception

Abstract Interocularly transferred motion aftereffects occur immediatelv after exposure to moving stimuli but are no longer demonstrable 7 min later. By contrast, opposite dichoptic motion aftereffects occur both immediately after exposure and 7 min later, with no evidence of a decrease over time. The results imply that the processing of motion aftereffects and hence, by extension, motion perception occurs in parallel systems.

Interference in colour-contingent motion after-effects.

When colour-contingent motion after-effects (MAEs) are induced with spirals that contain both colour and brightness contrast, the MAE is not apparent immediately after adaptation but does appear on a delayed test. However, when induced with stimuli that contain only colour contrast, the colour-contingent MAE is apparent immediately and decreases on a delayed test. The results are interpreted as indicating that units sensitive to brightness contrast can interfere with those that are sensitive to colour. It also seems necessary to modify or re-evaluate the fatigue theory of negative after-effects.

Student gender stereotypes: contrasting the perceived maleness and femaleness of mathematics and language

The purpose of this study was to evaluate the gender stereotypes endorsed by elementary and high school students regarding mathematics and language. We developed a questionnaire allowing students to rate mathematics and language as either male or female domains and administered it to a sample of 984 elementary and high school French‐speaking Canadian students (Grades 6, 8, and 10). Results showed that, with the exception of Grade 6 boys, students did not believe that mathematics was a male domain, or even conceived of mathematics as a predominantly female domain, suggesting that the traditional stereotype favouring boys in mathematics might have changed over the past few years. Moreover, language was clearly viewed as a female domain. Overall, our findings suggest that boys seem to be in need of encouragement in school, especially regarding language, where the advantage given to girls is particularly salient.

Persistence of simple and contingent motion aftereffects

Jones and Holding (1975) showed that orientation-contingent color aftereffects can persist for at least 3 months, but are depleted by repeated testing. We applied the same paradigm to a simple motion aftereffect (MAE) and found that it can persist for up to 1week and is only slightly diminished by testing. It was further found that simple MAEs appear to persist longer than color-contingent MAEs, although when procedures for inducing and measuring both kinds of aftereffect are equalized, contingent MAEs last longer. Finally, no tendency was found for color-contingent MAEs to diminish with repeated testing. Although both simple and color-contingent MAEs can be relatively persistent, there are certain differences between them. Furthermore, contingent aftereffects should not be considered interchangeable, as there appear to be large differences in the persistence of orientation-contingent color aftereffect and color-contingent MAEs.

Gender and fitness to stand trial. A 5-year review of remands in Québec.

Over the past 25 years, criminologists, psychologists, psychiatrists, and sociologists have shown an increased interest in the issue of differential treatment of men and of women at various stages of the criminal justice process (Adler & Simon, 1976; Allen, 1987; Bertrand, 1998; Bishop & Frazier, 1984; Channels & Herzberger, 1993; Chesney-Lind, 1987; Crites & Hepperle, 1987; Daly, 1994; Frazier & Hunt, 1998; Heilbrun & Heilbrun, 1986; Julian, 1993; Laberge, Morin, & Armony, 1997; Merlo & Pollock, 1995; Moyer, 1992; Riley, 1998; Steadman, 1987). The fact that women are less likely than men to commit crimes has, ironically, led criminologists to articulate two opposing views regarding the effect of gender on criminal justice outcomes: the ‘‘chivalry’’ or ‘‘paternalistic’’ theory and the ‘‘evil woman’’ or ‘‘punitive’’ theory. The ‘‘chivalry’’ theory holds that female offenders are treated more leniently than males. According to this view, women are less likely to be arrested and if found guilty, they receive shorter sentences than their male counterparts (Pollak, 1950; Simon, 1979). By contrast, the ‘‘evil woman’’ theory holds that female offenders are treated more severely than males for similar offenses. According to this view, women are more likely than men to be incarcerated and to receive longer sentences because their behavior deviates from stereotyped sex-role expectations (Simon, 1979). Most studies attempting to examine these theories have focused on sentencing practices. In a review of the literature on differential treatment in sentencing and parole decisions, Parisi (1982) found that in general, women are treated more

Sex and Gender Comparisons: Does Null Hypothesis Testing Create a False Dichotomy?

In an ongoing debate about the value of doing tests for sex differences, those in favour claim that if sex differences exist, it is important to know about them. However, the null hypothesis (NH) tests that are used for inferring group differences can detect only mean differences and provide no information about how the differences are distributed across groups. Theoretical and empirical examples show how NH rejection can occur when only a small proportion of individuals differ from all others, demonstrating that these tests are incapable of supporting inferences to general group differences. This forces a reevaluation of sex difference research which has been interpreted as distinguishing males from females in general, particularly where inferences have been to general biological factors. However, even knowing the limitations of these tests may not lead to more judicious interpretations in the context of an androcentric culture which dichotomizes the sexes.