Perception
-
Randomized Controlled Trial Clinical Trial
Classical and inverted White's effects.
In classical White's effect, intermediate-luminance targets appear lighter when they interrupt the dark stripes of a grating and darker when they interrupt the light stripes. The effect is reversed when targets are of double-increment or double-decrement luminance, relative to the luminances of grating stripes. To find a common explanation for classical and inverted effects, we ran two experiments. ⋯ This result weakens transparency-based accounts of White's effect. In experiment 2, we varied grating contrast and target luminance to measure the classical effect in seven intermediate-target cases, as well as the inverted effect in four double-increment and four double-decrement cases. Both types of effect are explained by a common model, based on assimilation to the top region and contrast with the interrupted region, weighted by adjacency along the luminance continuum.
-
Carryover of stimuli in sequential judgments was studied for a visual assessment task involving estimation of the percentage cover of black circles on a white image. Seven image types with different levels of cover density were arranged in a sequentially balanced design in which each image type was preceded the same number of times by all image types. In the absence of carryover, when images were preceded by images with the same cover density, the response scores were well fitted by a power function of percentage cover with a mean exponent of 0.73 over subjects. ⋯ However, the magnitude of the carryover effect showed little evidence of increasing with difference in cover between successive images. Nonparametric and parametric methods for testing for carryover are presented. The need for development of psychological models to explain the proposed statistical models is discussed.
-
A human observer can smoothly pursue her/his own voluntarily moved hand with the eyes in total darkness. The effects of a perceived stationary surface during ocular pursuit of the invisible hand were investigated. ⋯ It was found that smooth pursuit of the invisible hand occurred in the Ganzfeld as well as in total darkness, but was replaced by frequent saccades when a stationary surface was perceived through either the visual or the tactile sense. The results obtained with a Ganzfeld suggest that light alone does not prevent smooth pursuit of the invisible hand, and those obtained with a stationary surface suggest that perception of such a surface prevents smooth pursuit of the invisible hand and evokes saccades, regardless of the sense modality.
-
Historical Article
All that glitters: a review of psychological research on the aesthetics of the golden section.
Since at least the time of the Ancient Greeks, scholars have argued about whether the golden section-a number approximately equal to 0.618-holds the key to the secret of beauty. Empirical investigations of the aesthetic properties of the golden section date back to the very origins of scientific psychology itself, the first duties being conducted by Fechner in the 1860s. In this paper historical and contemporary issues are reviewed with regard to the alleged aesthetic properties of the golden section. ⋯ As well, brief reference is made to research on natural occurrences of the golden section, and to ancient and medieval knowledge and application of the golden section, primarily in art and architecture. Two major sections then discuss and critically examine empirical studies of the putative aesthetic properties of the golden section dating from the mid-19th century up to the 1950s, and the empirical work of the last three decades, respectively. It is concluded that there seems to be, in fact, real psychological effects associated with the golden section, but that they are relatively sensitive to careless methodological practices.
-
Inspection of a visual scene rotating about the vertical body axis induces a compelling sense of self rotation, or circular vection. Circular vection is suppressed by stationary objects seen beyond the moving display but not by stationary objects in the foreground. We hypothesised that stationary objects in the foreground facilitate vection because they introduce a relative-motion signal into what would otherwise be an absolute-motion signal. ⋯ The effect of stationary objects was particularly evident at low stimulus velocities. At low velocities a small stationary point significantly increased vection magnitude in spite of the fact that, at higher stimulus velocities and with other stationary objects in view, fixation on a stationary point, if anything, reduced vection. Changing the position of the stationary objects in the field of view did not affect vection latencies or magnitudes.