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.     

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.     

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.     

Error patterns in a chord keyboard response task

Errors in a serial choice-reaction time experiment employing two-finger chord responses to alphabetic stimuli are shown to be distributed in a significantly non-random fashion. Two factors are postulated which are relevant to prediction of the error response. These are the presence or absence of a common finger, and the difference in finger separation, between the actual and the required response. It is suggested that the chord response is coded in terms of a pattern (the distance between the two response components). Responses which mirror the correct response about the centre of the hand are also shown to be significantly more frequent.