Short-term memory digit-span performance under auditory and visual contexts as a function of rate of digit presentation

Size of Audience, Gender, and Digit-Rate Effects on Short-Term Memory

Short-term memory tests were given to 101 undergraduate volunteers (33 men and 68 women) under three levels of audience size (2 observers, 1 observer, and alone condition) using different rates (1 sec. and 3 sec.) of computer-generated random numbers. Subjects were instructed to recall 25 random digits (presented sequentially on a computer screen) immediately after their display. A mixed 2 × 2 × 3 split-plot analysis of variance showed a significant effect for rate of digit presentation and Newman-Keuls post hoc pairwise comparisons showed differences between men and women with 2 observers present under the 3-sec. digit rate (men scored higher). Gender differences also occurred in the extent to which subjects profited from the 3-sec. (simpler) digit-rate condition as a function of the presence or absence of an audience (three-way interaction). Women profited in the “alone” condition and men did not, yet men profited in the audience-present conditions and women did not. “Social facilitation” interpretations in the context of gender analyses are discussed.

Sex, Modality, and Cognitive Strategy Effects on Short-Term Memory as a Function of Rate of Computerized Digit Presentations

Short-term memory tests were given to 111 undergraduate volunteers (44 men and 67 women) under varying modes of presentation (auditory, visual, and auditory-visual combined) using different rates (1 sec. and 3 sec.) of computer-random digits. Subjects were instructed to “chunk” mentally 25 random digits (presented sequentially on a computer screen) into 5 sets of 5 digits (1 to 5) or to “rote” memorize all 25 digits for immediate recall. A mixed 2 × 2 × 2 × 3 split-plot analysis of variance showed a significant effect for rate of digit presentations, and there was a significant interaction between sex and rate of digit presentations. Men profited more from the 3-sec. rate than women, yet at the 1-sec. rate, women had higher short-term memory scores than men. There were no significant main effects for modality or cognitive strategy. Sex differences for digit-span tasks here were compared with sex differences from other studies for related tasks such as rapid matching of digit “strings.”

Mental Arithmetic as a Function of Computerized Digit Rates, Gender, and Size of Audience

Mental-arithmetic tests were given to 117 undergraduate volunteers (40 men and 77 women) using three rates (between groups) of digit presentation (1 sec., 2 sec., and 3 sec.) under three (within-group) sizes of audience (2 observers, 1 observer, and alone condition). Subjects were instructed to sum mentally three sets of 25 numerals ranging from 1 to 5 in computer-generated random sequences, under each of the three audience conditions. A mixed 2×3×3 split-plot analysis of variance of correct scores showed a significant main effect for rate of digit presentation, and post hoc Scheffé tests of multiple comparisons showed significant differences between the 1-sec. rate and each of the other rates (2 sec. or 3 sec.), yet no significance between 2-sec. and 3-sec. rates indicating a “critical threshold” has been identified with implications for computer-scrolled numerical information. Also, there was a significant two-way interaction between gender and size of audience. Post hoc Newman-Keuls comparisons showed women scored higher than men in the one-observer condition while men scored higher than women in the two-observer condition. Interpretations regarding interpersonal relationships and social inhibition were offered.

Acoustic masking disrupts time-dependent mechanisms of memory encoding in word-list recall

Recall of recently heard words is affected by the clarity of presentation: Even if all words are presented with sufficient clarity for successful recognition, those that are more difficult to hear are less likely to be recalled. Such a result demonstrates that memory processing depends on more than whether a word is simply "recognized" versus "not recognized." More surprising is that, when a single item in a list of spoken words is acoustically masked, prior words that were heard with full clarity are also less likely to be recalled. To account for such a phenomenon, we developed the linking-by-active-maintenance model (LAMM). This computational model of perception and encoding predicts that these effects will be time dependent. Here we challenged our model by investigating whether and how the impact of acoustic masking on memory depends on presentation rate. We found that a slower presentation rate causes a more disruptive impact of stimulus degradation on prior, clearly heard words than does a fast rate. These results are unexpected according to prior theories of effortful listening, but we demonstrated that they can be accounted for by LAMM.

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.

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.

Cerebral asymmetry in dementia: effect of context on hemi-attention

The duration of the orienting response toward the left or right hemispace as a function of bright light and noise levels was evaluated in 6 demented elderly patients. Tentative findings of cerebral asymmetry suggest light may differentially activate the left hemisphere.