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Recent research examined the effects of chewing gum on attention and reported a significant interaction of gum chewing with time. Using a crossover within-subject design, the present study examined the effect of gum chewing on sustained attention in healthy adults over a period of 30 min. The results revealed a significant main effect of time and a(More)
Vision is sensitive to first-order luminance modulations and second-order modulations of carrier contrast. Our knowledge of the temporal properties of second-order vision is insufficient and contradictory. Using temporal summation and reaction time paradigms, we found that the type of visual noise (static or dynamic) determines the temporal properties of(More)
A simple scheme for deriving relative depth (time-to-collision, or TTC) from optic flow is developed in which the total flow is first sensed by unconnected motion (imperfect filter) sensors and then the rotational component is subtracted to yield the translational component. Only the latter component yields depth information. This scheme is contrasted with(More)
Previous studies have specified the foveal pattern that is seen most efficiently, with the assumption that the waveform of the best pattern matches the impulse response of the most sensitive visual filter. We measured the threshold contrast for circular, collinear, and orthogonal Gabor stimuli of 6 Hz temporal frequency presented 7 deg above the fixation(More)
The sensitivity of the visual system to changes in velocity over time was investigated using the approach that Rashbass [(1970) Journal of Physiology, 210, 165-186] applied to luminance. Pairs of motion impulses (jumps) were presented, and thresholds for discriminating these pairs of impulses from a stationary display were determined. The results were(More)
Continuously, moving objects under continuous illumination can be seen to move in a direction opposite to their actual motion. This illusory reversed motion can be explained as due to discrete temporal sampling of the moving stimulus by the visual system. If temporal sampling lies behind the illusory motion, then the probability of illusory motion should(More)
The field of depth recovery from optic flow has recently experienced much growth, both on the theoretical and on the empirical fronts. Unfortunately, the theoretical results are not as widely known to perception workers as they might be. This article gives a simple analysis of the information for depth present in optic flow. It also reviews the(More)
Impairments of attention are cardinal features of attention deficit hyperactivity disorder (ADHD) and can seriously affect the daily life of children with ADHD. Despite effective treatment strategies, there is a need of further treatment options that can be added to available and well established treatments. Further treatment options are needed since(More)
The aim of this study was to use an equivalent noise paradigm to investigate the development and maturation of motion perception, and how the underlying limitations of sampling efficiency and internal noise effect motion detection and direction discrimination in school-aged children (5-14 years) and adults. Contrast energy thresholds of a 2c/deg sinusoidal(More)