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H A Shepard

Publications and source records attributed to H A Shepard.

2 recordsLinked to original sources

Ganzfeld perceptual field and gender effects on short-term memory as a function of rate of digit presentation.

Efforts to enhance short term memory for digit span (in serial recall) included the Ganzfeld perceptual field and variation in the rate (interstimulus interval: 1 sec., 2 sec., 3 sec.) of 25 auditorily presented computer-generated random numbers (1 to 5). Undergraduate volunteers (52 men and 91 women) wore goggles consisting of halves of translucent ping-pong balls while viewing a red lamp and listening to 60 decibels of white noise. Control subjects wore goggles with clear plastic lenses. Participants were instructed to recall 25 random digits in the correct series (vocalized sequentially through headphones worn by the subjects) immediately after their presentations. A mixed 2 x 2 x 3 split plot analysis of variance yielded a significant effect for digit rates, and post hoc Scheffe tests of multiple comparisons showed differences in recall between interstimulus intervals of 1 and 2 sec., 1 and 3 sec., and 2 and 3 sec. Other Scheffe comparisons showed that men scored higher than women with the 3-sec. interstimulus interval and with the "clear" perceptual field. Ganzfeld may have reduced distractibility for women as compared with recall following the "clear" perceptual field. Serial-position effects favored "primacy," yet the "recency effect" was seen within the last 5 serial positions.

Adult↗

Time estimation: effects of cognitive task, presentation rate, and delay.

The variables of which subjective time is a function extend throughout a myriad of "people, places, and things." This study measured subjective estimations of time as a function of complexity of cognitive task including arithmetic and recall (within subjects), the rate of stimulus (digit span) information (between subjects), and the delay between stimulus presentation and estimations of time (between subjects). A mixed analysis of variance 2 x 2 x 3 (repeated-measures) factorial design showed that retrospective time estimations were significantly different as a function of the main effects of rate of digit presentation and delay. Men and women showed no differences with no significant interactions so their data were pooled. Quotient values for ratios of delayed versus immediate estimates and slow versus fast rates showed overestimates of "real time." Explanations based on the "storage-size model," the "attention-allocation" model, and comparisons with Pedri and Hesketh's 1993 data are discussed.

Adult↗