We used a pedestal test [Lu & Sperling (1995a). Vision Research, 35, 2697-2722] to determine whether motion discrimination of contrast-modulated gratings has different properties at low contrast (4.5%) and at high contrast (45%). The amplitude-modulated gratings consisted of a 5 c/deg static carrier modulated by a moving 1 c/deg contrast envelope. We found that when contrast is low direction di...

At durations shorter than about 150 msec, a complex grating comprising a static 1-c/deg grating and a moving 3-c/deg grating is perceived as moving in the direction opposite that of the physical direction of motion. Here the phenomenon is further examined by measuring the perceived direction of motion of the fused images of a 1-c/deg grating presented to one eye and a moving 3-c/deg grating pre...

We compared the sensitivity of adults and children aged 3-10 years to first- and second-order motion and form. For first-order stimuli, at all ages sensitivity was better for motion than form, and motion thresholds were better at 6 Hz than at 1.5 Hz. For second-order stimuli, at all ages sensitivity was better for form than motion, and motion thresholds were better at 0.25 cyc/deg than at 1 cyc...

In this study we used a modified Stroop word-color task in which the target was a centrally fixated color frame and the distractor was an incompatible, compatible or non-color word. In Experiment 1 distractors were located either within (the inside condition) or outside the frame, at distances of 1.3 deg (near-outside condition) or 2 deg (far-outside condition). In Experiment 2 only the inside ...

Individual foraging ants are known to rely on views of their surroundings for route learning and for pinpointing goals. Different strategies have been proposed to explain how ants might process visual information for navigation, but little is known about the actual development and nature of the view-based strategies used by ants in complex natural environments. Here, we constrained the knowledg...

1. Let f, g ∈ C[T ] be nonconstant and relatively prime. a) If f−g 6= 0, show deg(f−g) ≥ (1/2) deg f+1, or equivalently deg f ≤ 2(deg(f−g)−1). b) Find infinitely many examples where equality occurs in the conclusion of part a. Start with an example where deg f = 3 and deg g = 2. c) When the hypothesis of relative primality is dropped, is part a still true? d) Find a lower bound on deg(f − g) in...

We can write the polynomial solution of the second order linear differential equation of hypergeometric-type φ(x)y + ψ(x)y + λy = 0, where φ and ψ are polynomials, deg φ ≤ 2, degψ = 1 and λ is a constant, among others, by using the Rodrigues operator Rk(φ,u) (see [3]) where u is certain linear operator which satisfies the distributional equation

Our ability to discriminate motion direction in a Gabor patch diminishes with increasing size and contrast, indicating surround suppression. Discrimination is also impaired by a static low-spatial-frequency patch added to the moving stimulus, suggesting an antagonism between sensors tuned to fine and coarse features. Using Bayesian staircases, we measured duration thresholds in motion-direction...