A digital noise and sine-wave generator

A circuit is described that will digitally generate three kinds of signal useful in auditory research: broad-band pseudorandom noise, low-pass-filtered Gaussian noise, and low-distortion sine waves. This digital circuit has two advantages over its analog counterparts, ease of calibration and adaptation to computer control.     

Pictorial interference with geometric shapes and achromatic shades

In two experiments, subjects were required to match printed names with subsequently displayed achromatic shades or geoinetric shapes. The presence of incongruent shades or shapes at the time of word display substantially slowed the RT for performing the match. This pictorial interference (interference due to a visual, nonlingalistic attributel was substantially attenuated, however, as the delay between the word display and shapes or shades to be matched was increased beyond 100 msec. These findings illnstrate the occurrence of a transitory automatic pathway activation from an irrelevant pictorial attribute, which may be contrasted with the verbal interference effects typically observed in Stroop-naming tasks. In both our tasks and the Stroop task, selectiwe attention fails when a stimulus must be transformed to another form of encoding in the presence of a competing stimulns which is already close to that form.