J. Scott Saults

On the Capacity of Attention: Its Estimation and Its Role in Working Memory and Cognitive Aptitudes

Working memory (WM) is the set of mental processes holding limited information in a temporarily accessible state in service of cognition. We provide a theoretical framework to understand the relation between WM and aptitude measures. The WM measures that have yielded high correlations with aptitudes include separate storage-and-processing task components, on the assumption that WM involves both storage and processing. We argue that the critical aspect of successful WM measures is that rehearsal and grouping processes are prevented, allowing a clearer estimate of how many separate chunks of information the focus of attention circumscribes at once. Storage-and-processing tasks correlate with aptitudes, according to this view, largely because the processing task prevents rehearsal and grouping of items to be recalled. In a developmental study, we document that several scope-of-attention measures that do not include a separate processing component, but nevertheless prevent efficient rehearsal or grouping, also correlate well with aptitudes and with storage-and-processing measures. So does digit span in children too young to rehearse.

The role of verbal output time in the effects of word length on immediate memory

In three experiments, we examined the role of delays within overt verbal responding in causing effects of word length on immediate recall. Although a phonological memory decay mechanism has been implicated by past research on word length effects, the exact basis of the effect remains unclear. The added difficulty of recalling longer words could arise both while subjects attempt to rehearse words silently and while they attempt to repeat words aloud. To examine the latter mechanism, the lengths of words in the first and second halves of lists to be recalled were varied independently, and both forward and backward recall orders were used. Recall of each word was found to be influenced by the total pronunciation time for all items to be recalled prior to that word, although there was an additional advantage for the last item output. The results clarify and generally support the theory of the articulatory loop, and the method permits an improved analysis of immediate memory into decay-based and other factors.

Scope of Attention, Control of Attention, and Intelligence in Children and Adults

Recent experimentation has shown that cognitive aptitude measures are predicted by tests of the scope of an individual’s attention or capacity in simple working memory tasks and also by the ability to control attention. However, these experiments do not indicate how separate or related the scope and control of attention are. An experiment with 52 children (10 to 11 years old) and 52 college students included measures of the scope and control of attention, as well as verbal and nonverbal aptitude measures. The children showed little evidence of using sophisticated attentional control, but the scope of attention predicted intelligence in that group. In adults, both the scope and control of attention varied among individuals and accounted for considerable individual variance in intelligence. About one third that variance was shared between scope and control, and the rest was unique to one or the other. Scope and control of attention appear to be related but distinct contributors to intelligence.

Life-Span Development of Visual Working Memory: When is Feature Binding Difficult?

We asked whether the ability to keep in working memory the binding between a visual object and its spatial location changes with development across the life span more than memory for item information. Paired arrays of colored squares were identical or differed in the color of one square, and in the latter case, the changed color was unique on that trial (item change) or was duplicated elsewhere in the array (color-location binding change). Children (8-10 and 11-12 years old) and older adults (65-85 years old) showed deficits relative to young adults. These were only partly simulated by dividing attention in young adults. The older adults had an additional deficiency, specifically in binding information, which was evident only when item- and binding-change trials were mixed together. In that situation, the older adults often overlooked the more subtle, binding-type changes. Some working memory processes related to binding undergo life-span development in an inverted-U shape, whereas other, bias- and salience-related processes that influence the use of binding information seem to develop monotonically.

A Central Capacity Limit to the Simultaneous Storage of Visual and Auditory Arrays in Working Memory

If working memory is limited by central capacity (e.g., the focus of attention; N. Cowan, 2001), then storage limits for information in a single modality should apply also to the simultaneous storage of information from different modalities. The authors investigated this by combining a visual-array comparison task with a novel auditory-array comparison task in 5 experiments. Participants were to remember only the visual, only the auditory (unimodal memory conditions), or both arrays (bimodal memory conditions). Experiments 1 and 2 showed significant dual-task tradeoffs for visual but not for auditory capacity. In Experiments 3-5, the authors eliminated modality-specific memory by using postperceptual masks. Dual-task costs occurred for both modalities, and the number of auditory and visual items remembered together was no more than the higher of the unimodal capacities (visual: 3-4 items). The findings suggest a central capacity supplemented by modality- or code-specific storage and point to avenues for further research on the role of processing in central storage.

The Role of Attention in the Development of Short-Term Memory: Age Differences in the Verbal Span of Apprehension

In previous studies of memory span, participants have attended to the stimuli while they were presented, and therefore have had the opportunity to use a variety of mnemonic strategies. In the main portion of the present study, participants (first- and fourth-grade children, and adults; 24 per age group) carried out a visual task while hearing lists of spoken digits and received a post-list digit recall cue only occasionally, for some lists. Under these conditions, list information presumably must be extracted from a passively held store such as auditory sensory memory. The results suggest that each individual has a core memory capacity limit that can be observed clearly in circumstances in which it cannot be supplemented by mnemonic strategies, and that the capacity limit appears to increase with age during childhood. Other, attention-demanding processes also contribute to memory for attended lists.

Alcohol effects on performance monitoring and adjustment: affect modulation and impairment of evaluative cognitive control.

Alcohol is known to impair self-regulatory control of behavior, though mechanisms for this effect remain unclear. Here, we tested the hypothesis that alcohols reduction of negative affect (NA) is a key mechanism for such impairment. This hypothesis was tested by measuring the amplitude of the error-related negativity (ERN), a component of the event-related brain potential (ERP) posited to reflect the extent to which behavioral control failures are experienced as distressing, while participants completed a laboratory task requiring self-regulatory control. Alcohol reduced both the ERN and error positivity (Pe) components of the ERP following errors and impaired typical posterror behavioral adjustment. Structural equation modeling indicated that effects of alcohol on both the ERN and posterror adjustment were significantly mediated by reductions in NA. Effects of alcohol on Pe amplitude were unrelated to posterror adjustment, however. These findings indicate a role for affect modulation in understanding alcohols effects on self-regulatory impairment and more generally support theories linking the ERN with a distress-related response to control failures.

Children's Working-Memory Processes: A Response-Timing Analysis

Recall response durations were used to clarify processing in working-memory tasks. Experiment 1 examined childrens performance in reading span, a task in which sentences were processed and the final word of each sentence was retained for subsequent recall. Experiment 2 examined the development of listening-, counting-, and digit-span task performance. Responses were much longer in the reading-and listening-span tasks than in the other span tasks, suggesting that participants in sentence-based span tasks take time to retrieve the semantic or linguistic structure as cues to recall of the sentence-final words. Response durations in working-memory tasks helped to predict academic skill and achievement, largely separate from the contributions of the memory spans themselves. Response durations thus are important in the interpretation of span task performance.

A neural region of abstract working memory

Over 350 years ago, Descartes proposed that the neural basis of consciousness must be a brain region in which sensory inputs are combined. Using fMRI, we identified at least one such area for working memory, the limited information held in mind, described by William James as the trailing edge of consciousness. Specifically, a region in the left intraparietal sulcus was found to demonstrate load-dependent activity for either visual stimuli (colored squares) or a combination of visual and auditory stimuli (spoken letters). This result was replicated across two experiments with different participants and methods. The results suggest that this brain region, previously well known for working memory of visually presented materials, actually holds or refers to information from more than one modality.

Investigation of Student Status, Background Variables, and Feasibility of Standard Tasks in Cognitive Aging Research

Data are reported on a variety of cognitive tasks from 62 college students and 362 nonstudent adults between 20 and 79 years of age. The goals of the project were as follows: (a) to investigate the validity of the practices of using college students and adults over age 65 in studies of cognitive aging, (b) to examine the influence of a variety of background variables on age trends in cognitive performance, and (c) to initiate the development of standard tasks to assist in the description of subject samples in cognitive aging research. The age trends in cognitive performance were relatively independent of an assortment of background variables, but because college students were atypical of their age group in several performance measures they may be suspect as the young-adult control subjects in investigations involving these types of measures. Adults over the age of about 65 appear to exhibit accelerated slowing of speeded performance, but in other respects perform about as one would expect on the basis of the age trends observed between the ages of 20 and 65.