An ideal detector is derived for the discrimination of arbitrary stimuli in the two-alternative forced-choice paradigm. The ideal detector's performance is assumed to be limited only by quantal fluctuations, the optics of the eye, and the size and spacing of the receptors in the retinal mosaic. Detailed predictions are presented for two-point acuity and hyperacuity tasks. The ideal detector's t...

The present paper gives a classification of the expressive power of two-variable least fixed-point logics. The main results are: 1. The two-variable fragment of monadic least fixed-point logic with parameters is as expressive as full monadic least fixed-point logic (on binary structures). 2. The two-variable fragment of monadic least fixed-point logic without parameters is as expressive as the ...

Studies of chromatic discrimination are typically based on homogeneously colored patches. Surfaces of natural objects, however, cannot be characterized by a single color. Instead, they have a chromatic texture, that is, a distribution of different chromaticities. Here we study chromatic discrimination for natural images and synthetic stimuli with a distribution of different chromaticities under...

PURPOSE Simple decompression of the ulnar nerve has outcomes similar to anterior transposition for cubital tunnel syndrome; however, there is no consensus on the proper technique for patients with an unstable ulnar nerve. We hypothesized that 1) simple decompression or anterior ulnar nerve transposition, depending on nerve stability, would be effective for cubital tunnel syndrome and that 2) th...

OBJECTIVE To evaluate the pressure perception thresholds on the pulp of two fingers (index and little fingers), among a Brazilian population with no nerve injury or neuropathy. METHODS We used the Pressure-Specified Sensory Device (a computerized device) to derive static and dynamic normal pressure perception thresholds and two-point discrimination distances. RESULTS We tested finger sensit...

OBJECTIVE This study focusses on the optimal paradigm for simultaneous assessment of auditory and phonemic discrimination in clinical populations. We investigated (a) whether pitch and phonemic deviants presented together in one sequence are able to elicit mismatch negativities (MMNs) in healthy adults and (b) whether MMN elicited by a change in pitch is modulated by the presence of the phonemi...

Full-thickness skin grafts from the hypothenar area were used to reconstruct 25 digits in a group of 20 patients. The results were evaluated objectively and subjectively at an average of 9.5 months after operation for sensibility, durability, and appearance. Eighty-six percent of the patients had two-point discrimination of 10 mm or less, with one half of them having two-point discrimination of...

BACKGROUND The minimum distance between two stimulus points on the skin, which are perceived as distinct points, is defined as two point discrimination (TPD). Among the two types of TPD, i.e., static and dynamic, static two-point discrimination (STPD) is commonly used to determine digital nerve integrity. Local flaps usually do well in maintaining sensibility of the covered area in terms of two...