QUESTION How precisely can objects, located in different depth planes, be aligned to the same visual direction? METHODS Twenty normal observers were presented with vertical Vernier lines at various stereodisparities. They had to judge whether the lower, anterior line was located on the right- or left-hand side of the upper, posterior line. RESULTS Over a stereodisparity range from zero to 6...

In object recognition, features are thought to be processed in a hierarchical fashion from low-level analysis (edges and lines) to complex figural processing (shapes and objects). Here, we show that figural processing determines low-level processing. Vernier offset discrimination strongly deteriorated when we embedded a vernier in a square. This is a classic crowding effect. Surprisingly, crowd...

Our impressive sensitivity to vernier offsets as compared to resolution acuity has long inspired vision researchers to study the phenomena in great detail. In this study we use the test-pedestal framework to compare resolution and vernier acuity. In these experiments the test stimulus is the same for both tasks, only the pedestals differ. When thresholds are expressed in common units of test st...

Vernier acuity thresholds were obtained psychophysically in three adult barn owls with vertical bars and sinusoidal gratings. A minimal displacement threshold of 0.58 arcmin was observed with the bar stimulus under binocular viewing conditions. The mean binocular bar threshold was 2.51 arcmin. Bar thresholds were lower than grating thresholds. Monocular thresholds, obtained in one bird only, we...

Vernier acuity depends on the integration of information from multiple photoreceptors. For this reason, vernier acuity thresholds ought to exhibit effects of stimulus size and contrast analogous to those that occur in area summation experiments. In this paper, we consider some area and contrast effects found in vernier acuity experiments, and explain them with a model of detection and discrimin...

Vernier acuity was measured in infants 1 to 14 months of age using a dynamic three alternative tracking paradigm. The location of the vernier offset would move randomly to one of three screen locations. An observer, unaware of the stimulus location, viewed the infant from behind a screen and guessed the position of the vernier offset. The magnitude of the vernier offset was controlled by a stai...

Vernier acuity, a form of visual hyperacuity, is amongst the most precise forms of spatial vision. Under optimal conditions Vernier thresholds are much finer than the inter-photoreceptor distance. Achievement of such high precision is based substantially on cortical computations, most likely in the primary visual cortex. Using stimuli with added positional noise, we show that Vernier processing...

To evaluate the relative importance of local feature and spatial filter models for hyperacuity, vernier thresholds were determined for gratings consisting of a fundamental (Fo) and third harmonic (3F) presented alone, and added together in compound gratings where the relative phase offsets of 3F to Fo was 0, 90, 180 and 270 degrees. Thresholds were determined for a range of spatial frequencies ...

We present the Vernier optical fiber Shape-8 double-ring resonator consisting of two optical fibre rings with a gain coupling cofficent path connecting the two rings. One of the ring is twisted to form an enclosed Shape-8. Photonic graphical techniques are applied to obtain the transfer functions between input and output ports of the photonic circuit. The Shape-8 Vernier Double Ring optical res...

For rapidly translating targets, vernier thresholds correspond to millisecond asynchronies between targets. The 'temporal hypothesis' is that these thresholds reflect the limiting sensitivity of asynchrony detectors. Previous studies showed that temporal thresholds are generally higher than vernier thresholds, but failed to reject the 'temporal hypothesis' because stimuli had differing spatiote...