Search processes for detecting repeated items In a visual display

Evidence for successive serial exhaustive searches was found in a task requiring detection of repeated letters in visually presented lists of varying length. The time per comparison was 25 msec. Important differences in processing appeared between instances of adjacent repeated letters and instances of nonadjacent repeated letters.     

Extraretinal feedback and visual localization

The effect of saccades on visual localization was tested before, during, and after the eye movements. After saccades, localization errors were much less than the distance that the eyes had moved. It is argued that these results demonstrate that extraretinal feedback affects visual localization. The results also suggest that the feedback is related to acceleration rather than to position. Implications for inflow and outflow theories are discussed.     

A signal detection analysis of the effects of hearing on the visual recognition of two-digit numbers

A signal detection measure of visual recognition was used to assess the visual recognition of two-digit numbers in three different conditions: (1) voicing of the number as it was presented visually; (2) voicing of a different number than the one presented; and (3) no voicing. The three treatment means were significantly different, with matched voicing resulting in the best performance and no voicing, in the worst. There was no evidence that the treatments differentially affected response criteria.     

Evidence for an addition to the reading scan hypothesis

Letters were tachistoscopically presented in pairs to the left or right of fixation for 40 msec. The pair consisted of a target letter (B, D, P, or T) and a noise letter (all other letters of the alphabet except I), with the noise letter appearing either to the inside or the outside of the stimulus letter. S’s task was to report verbally the target letter as fast as possible. Reaction times and number of errors indicated that there was more interference when the noise letter occurred further from the fixation point than the target letter for both the left and right visual field. Since a reading scan cannot account for the results in the right visual field, an outside-toward-fixation scan is proposed. An analysis of the different kinds of errors indicated that the outside to fixation scan is more primitive than the reading scan in that it produces less detailed information about the letters than does the reading scan.     

A conceptual category effect in visual search: O as letter or as digit

Evidence is presented for a processing mechanism in visual recognition that depends upon how the stimulus array is conceptually categorized rather than upon its physical characteristics. Ss had to detect a letter or digit target in a field of letters or digits. When target and field were of the same category, reaction time increased with display size. When target and field category differed, reaction times were independent of display size. This category effect held even for the ambiguous target character 0 that yielded reaction time functions appropriate to how it was specified prior to presentation: as “zero” or as “ō.”     

Schedule control of the vocal behavior of Cebus monkeys

The vocal behavior of three Cebus monkeys was maintained by fixed-ratio schedules of response dependent reinforcement at values between fixed-ratio 1 and fixed-ratio 15. In one monkey that was exposed to variable-interval, fixed-interval, and conjunctive fixed-ratio fixed-interval schedules of reinforcement, vocal responding occurred at a low rate, but schedule-appropriate patterns were maintained. The rates and patterns of responding engendered indicated that the vocal operant can be brought under schedule control in the monkey by the use of response-dependent reinforcement.     

Positive interaction (induction) in multiple variable-interval, differential-reinforcement-of-high-rate schedules

The effect of increases in the rate of responding in one component of a multiple schedule upon the rate of responding in a second component was investigated. Pigeons were exposed to a multiple schedule where both components were initially variable-interval schedules having the same parameter value. After rate of key pecking stabilized, one component was changed to a schedule that differentially reinforced high rates of responding. Rate of reinforcement in this varied component was adjusted to remain equal to rate of reinforcement in the constant (variable-interval) component. Four of five pigeons showed a maintained increase in rate of responding during both the constant and varied components, even though rates of reinforcement did not change.