Summary knowledge of results for skill acquisition: support for the guidance hypothesis

Summary knowledge of results (KR) involves the presentation KR for each of a set of trials (e.g., 10) only after the last trial in the set has been completed. Earlier, Lavery (1962) showed that, relative to providing KR after each trial, a 20-trial summary KR was detrimental to performance in a practice phase with KR present but was beneficial for a no-KR retention test. Using a relatively simple ballistic-timing task, we examined summary lengths of 1 (essentially KR after every trial), 5, 10, and 15 trials, searching for an inverted-U relationship between summary length and retention performance as predicated by a guidance hypothesis for KR. During acquisition when KR was present and being manipulated, all groups showed improvements in performance across practice, while increased summary lengths generally depressed performance. However, in a delayed no-KR retention test, there was an inverse relation between the summary length in acquisition and absolute constant error on the retention test. A guidance hypothesis is favored to explain how, relative to immediate KR, long KR summaries can provide detrimental effects in acquisition while enhancing retention performance.     

Priming of face matching in amnesia.

Priming was studied in a task that required a speeded response to photographs of faces. On each trial, subjects viewed two faces and decided if the same person was shown twice or if two different people were shown. Both familiar and unfamiliar (i.e., well-known and unknown) faces were used, and some face pairs were repeated with a mean delay of about 10 min. Repetition was associated with faster reaction times in young subjects (Experiment 1) as well as in amnesic patients and age-matched control subjects (Experiment 2). The patients' reaction times were slower overall, although the magnitude of the priming effect did not differ from that in the control subjects. This preservation of a normal reaction-time facilitation in subjects with impaired recognition memory for faces occurred for both familiar and unfamiliar faces, suggesting that amnesia does not necessarily interfere with the acquisition of new information as indexed by this priming effect.     

Learning Consistent,Interactive, and Meaningful Task-Action Mappings: A Computational Model

Within the field of human-computer interaction, the study of the interaction between people and computers has revealed many phenomena. For example, highly interactive devices, such as the Apple Macintosh, are often easier to learn and use than keyboard-based devices such as Unix. Similarly, consistent interfaces are easier to learn and use than inconsistent ones. This article describes an integrated cognitive model designed to exhibit a range of these phenomena while learning task-action mappings: action sequences for achieving simple goals, such as opening a file in a word processor. The model, called TAL, is of a user who is familiar with the basic operations of a keyboard and mouse, but unfamiliar with the particular menu structures, words, and actions required to use the device. The model is constructed in Soar and employs a single set of architectural mechanisms. It exhibits behavior that captures human preference for consistent, interactive, and meaningful task-action mappings.     

Hemispheric Differences in Context Sensitivity During Lexical Ambiguity Resolution

Three experiments were conducted to investigate the influence of contextual constraint on lexical ambiguity resolution in the cerebral hemispheres. A cross-modal priming variant of the divided visual field task was utilized in which subjects heard sentences containing homonyms and made lexical decisions to targets semantically related to dominant and subordinate meanings. Experiment 1 showed priming in both hemispheres of dominant meanings for homonyms embedded in neutral sentence contexts. Experiment 2 showed priming in both hemispheres of dominant and subordinate meanings for homonyms embedded in sentence contexts that biased a central semantic feature of the subordinate meaning. Experiment 3 showed priming of dominant meanings in the left hemisphere (LH), and priming of the subordinate meaning in the right hemisphere (RH) for homonyms embedded in sentences that biased a peripheral semantic feature of the subordinate meaning. These results are consistent with a context-sensitive model of language processing that incorporates differential sensitivity to semantic relationships in the cerebral hemispheres.     

The effects of exposure duration and practice on the immediate memory spans of children and adults

Immediate memory spans for alphabetic items were determined for second-grade, fifth-grade, and adult subjects. Subjects were tested on three days, ten trials per day at each of three exposure durations: 15, 50, and 200 msec. One half of the subjects were presented with exposure durations in an ascending order, the other half in a descending order. The results indicated that immediate memory span increases with age and practice. The exposure duration effect depended on the order and day in which durations were presented. There was a suggestion that the exposure duration effect was also dependent upon the age and sex of the subject. The ordering of array positions from most accurately reported to least accurately reported was identical for all three age levels, indicating that scanning strategies are well established at an early age.     

Effect of subvocalization on memory for speech sounds.

Subjects in two groups were presented with sequences of 6 consonant-vowel syllables for ordered recall. Subjects in both groups were trained to suppress subvocalization. Only subjects in the feedback group were asked to suppress subvocalization during the experiment, while subjects in the no-feedback group were allowed to subvocalize during the memory task. Analysis of the electromyographic records showed a large decrease in subvocalization in the feedback condition, and results of the memory task revealed an increase in errors for this group. However, a comparison of errors within each group revealed an identical pattern of overall errors and intrusion errors on subvocalization and nonsubvocalization trials, and these results were identical in both groups. The results suggest that requiring subjects to simultaneously suppress subvocalization and remember syllables depresses performance slightly, but encoding of speech sounds in short-term memory occurs independently of subvocal activity during the memory task.