Frequency response characteristics for sinusoidal movement in the fovea and periphery

Threshold sensitivity was measured for sinusoidal movement of bright 1-deg lines against a dark background as a function of oscillation frequency and retinal location. Sensitivity was greatest in the fovea and at a frequency of 1–2 Hz. Peripheral sensitivity was more narrowly tuned than foveal sensitivity. The presence of a stationary reference line affected mainly the foveal sensitivity. The results are interpreted as evidence for both position- and velocity-sensitive mechanisms in the movement detection system.     

Associative facilitation and interference in the Stroop color-word task

It is difficult to name the color of a stimulus when the stimulus is a word naming a different color. When the word is congruent with the color in which it is written, color naming is much quicker. Similar results are also obtained when color-related words are used instead of color names. These results are taken as evidence for the operation of associative factors that could facilitate or impair performance in the color-word task.     

The detection of visual intensity differences by pigeons

Pigeons were trained in a conditional discrimination procedure to discriminate between visual stimuli that varied in intensity. The magnitude of the intensity difference ranged from 0.80 to 0.05 logarithmic units. Psychometric functions were calculated from the data and the mean difference threshold for the 11 subjects was approximately 0.12 logarithmic units. A signal-detection analysis of the data suggested that stimuli that were below the calculated threshold were detectible to the subjects.     

Short-term visual memory and pattern masking

The results of two experiments involving the matching of unfamiliar, nameless shapes (Gibson forms) indicated that a visual representation of a brief (30-100 ms) stimulus survives in a Short-Term Visual Memory (STVM) for 6 s or more after the onset of a pattern mask. On the basis of these results a possible alternative to Sperling's (1967) model for short-term memory for visual stimuli was presented. In this model it is assumed that recognition processes occupy several hundred milliseconds and continue after the arrival of the mask using the information available in STVM.     

Auditory evoked brain responses: Intensity functions from bipolar human scalp recordings

Average evoked brain responses were computed from four simultaneous recordings during binaural tone stimulation at 10 intensity levels. Amplitudes and latencies were measured for the prominent components, and linear regression coefficients were computed. The results indicate that the sensitivity of the evoked response to stimulus intensity is dependent upon the selection of the appropriate measure. Linear amplitude functions were demonstrated. Additional research relating these responses to psychophysical measures is suggested.     

Response latencies in human matching-to-sample

Optimum characterization of individual information-processing skills requires isolation of assessable components. In matching-to-sample, three elementary processes might be separated if a proposed model of serial, selfterminating search were supported: registration of the stimulus in short-term memory, comparison of the two registered stimuli, and execution of the identifying response. Support for the model was obtained when response latencies were examined as a function of left-to-right position of the target stimulus in a display, but quantitative estimates of components could not be made because of interactions between tasks and the linearity of the scanning process. A second experiment, which varied the number of comparison stimuli, yielded highly linear functions whose slopes and intercepts violated certain aspects of the model. Data on eye movements obtained in a third experiment again supported the basic model but indicated that median response latencies represent a confounding of optimal and suboptimal performances.