We examined the influence of context on fine orientation discrimination performance using sinusoidal grating patterns. Discrimination performance was impaired in the presence of modulated surrounds of the same spatial frequency, orientation, and contrast as the center. When center and surround were out-of-phase, separated by a gap of mean luminance, or very different in spatial frequency, perfo...

Measurement of sensitivity to differences in the rate of change of auditory signal parameters is complicated by confounds among duration, extent, and velocity of the changing signal. Dooley and Moore [(1988) J. Acoust. Soc. Am. 84(4), 1332-1337] proposed a method for measuring sensitivity to rate of change using a duration discrimination task. They reported improved duration discrimination when...

The spatial focus of attention has been suggested to resemble a spotlight, a zoom-lens, a simple gradient, or even a more complex center-surround profile. Here we review evidence from neuromagnetic recordings indicating that the spatial profile is not fixed but depends on the particular perceptual demands of the attention task. We show that visual search requiring spatial scrutiny for target di...

Contrast integration across space was studied in respect to stimulus extent and the spatial layout, using high-contrast stimuli. Contrast discrimination thresholds were measured (2AFC) by either increasing the size of a peripheral (2.4 degrees) Gabor signal (GS: lambda = 0.08 degree) or by increasing the number of GS elements in a circular arrangement. The supra-threshold mask (pedestal) was ei...

The present study demonstrates, for the first time, a specific enhancement of auditory spatial cue discrimination due to eye gaze. Whereas the region of sharpest visual acuity, called the fovea, can be directed at will by moving one's eyes, auditory spatial information is derived primarily from head-related acoustic cues. Past auditory studies have found better discrimination in front of the he...

Shape processing involves a progression from local to global analysis. A key aspect of this is the binding of distributed local features into an overall form followed by the extraction of the shape independently of its local contrast and spatial scales, so enabling the shape to be encoded based on its proportions without reference to its exact size or retinal location. Here we use contour- and ...

We used Gaussian blurred lines of same- and opposite-polarity to measure the effects of blur on 3-line spatial interval discrimination (bisection). The results of our experiments can be summarized as follows. Spatial interval discrimination (3-line bisection) thresholds are proportional to the separation of the lines (i.e. Weber's law). At the optimal separation, spatial interval discrimination...

Neurophysiological studies indicate the existence of an area in the extrastriate monkey cortex specialized for the processing of stimulus motion. The present investigation was conducted to determine whether a homologous area exits in the human cortex that underlies the processing and short-term storage of velocity information. Contrast detection and velocity discrimination thresholds were measu...

Egocentric tactile perception is crucial for skilled hand motor control. In order to better understand the brain functional underpinnings related to this basic sensorial perception, we performed a tactile perception functional magnetic resonance imaging (fMRI) experiment with two aims. The first aim consisted of characterizing the neural substrate of two types of egocentric tactile discriminati...

Firms’ fob prices can vary depending on the distance to the destination market for two reasons: (i) firms can charge a different markup (ii) they can offer a product with slightly different quality. In theoretical models, distance generally covers transport costs. This paper shows that the response of firms’ prices to changes in distance to the destination market depends on the formulation of t...