Children's working-memory processes: a response-timing analysis

Recall response durations were used to clarify processing in working-memory tasks. Experiment 1 examined children's 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.     

Stimulus-determined discrimination mechanisms for color search

Visual attention can be goal driven, stimulus driven, or a combination of the two. Here we report evidence for an unexpectedly stimulus-driven component of visual search for a target defined by color. Observers demonstrated a surprisingly cost-free ability to incorporate multiple classifiers in search for a target of one color from among distractors of other colors. A target color was presented among distractors that could change from trial to trial (intermixed presentation) or that remained constant across all trials in a block (blocked presentation). For blocked presentation, a single search classifier (a mechanism that segregates the target from distractors in color space) could be adopted, whereas for intermixed presentation different classifiers had to be used when the distractor colors changed. The benefit of blocked presentation was very small, suggesting that the appropriate classifier was determined very quickly in trials for which the classifier changed. The results suggest that the stimulus-driven activation of an appropriate stimulus classifier can be very efficient.     

The Microanalysis of Memory Span and Its Development in Childhood

It is not clear from the literature why, as children develop, there are important increases in memory span, the number of just-presented items that the participant can repeat in the correct serial order. To understand this, some recent results on capacity limits and processing rates were re-analyzed. We first describe results using a conventional measure of performance in immediate memory tasks that is affected by the list length (proportion correct). Next we describe results using a less conventional measure (number correct) that is unaffected by list length under circumstances in which attention to the list during its presentation is curtailed. This measure can estimate an individual's limited-capacity storage ability. Last, we examine measures of spoken response timing that do and do not change with list length. We show that unconventional measures that do not change with list length, but do change with development, are especially useful in assessing basic changes in information processing parameters, including increases in memory capacity and processing speed.     

Insights into spared memory capacity in amnestic MCI and Alzheimer's Disease via minimal interference

Impairment on standard tests of delayed recall is often already maximal in the aMCI stage of Alzheimer's Disease. Neuropathological work shows that the neural substrates of memory function continue to deteriorate throughout the progression of the disease, hinting that further changes in memory performance could be tracked by a more sensitive test of delayed recall. Recent work shows that retention in aMCI patients can be raised well above floor when the delay period is devoid of further material - 'Minimal Interference'. This memory enhancement is thought to be the result of improved memory consolidation. Here we used the minimal interference/interference paradigm (word list retention following 10 min of quiet resting vs. picture naming) in a group of 17 AD patients, 25 aMCI patients and 25 controls. We found (1) that retention can be improved significantly by minimal interference in patients with aMCI and patients with mild to moderate AD; (2) that the minimal interference paradigm is sensitive to decline in memory function with disease severity, even when performance on standard tests has reached floor; and (3) that this paradigm can differentiate well (80% sensitivity and 100% specificity) between aMCI patients who progress and do not progress to AD within 2 years. Our findings support the notion that the early memory dysfunction in AD is associated with an increased susceptibility to memory interference and are suggestive of a gradual decline in consolidation capacity with disease progression.     

Development of the ability to combine visual and acoustic information in working memory

Presentation of two kinds of materials in working memory (visual and acoustic), with the requirement to attend to one or both modalities, poses an interesting case for working memory development because competing predictions can be formulated. In two experiments, we assessed such predictions with children 7–13 years old and adults. With development, the ability to hold more information in the focus of attention could lead to an increase in the size of the trade‐off between modalities; if attention can hold A items during unimodal‐attention trials, then on average attention should hold A/2 of those same items during bimodal‐attention trials. If A increases with age, so would the dual‐task cost, A/2. The results clearly ruled out that possibility. It was the modality‐ or code‐specific components of working memory that improved with age and not the central component. We discuss various mechanisms that could have produced these results, including alternative attention‐based mechanisms. The findings point to a rich field for continued research.     

Perceptual Intuitionism

In the recent metaethical literature there has been significant interest in the prospects for what I am denoting ‘Perceptual Intuitionism’: the view that normal ethical agents can and do have non‐inferential justification for first‐order ethical beliefs by having ethical perceptual experiences, e.g., Cullison 2010, McBrayer 2010, Vayrynen 2008. If true, it promises to constitute an independent a posteriori intuitionist epistemology, providing an alternative to intuitionist accounts which posit a priori intuition and/or emotion as sources of non‐inferentially justified ethical beliefs. As it is formulated, it is plausible that a necessary condition for the view is the truth of Ethical Perception: normal ethical agents can and do have perceptual experiences (at least some of which are veridical) as of the instantiation of ethical properties. In this paper a sophisticated and promising account of Ethical Perception is offered. Extant objections are shown to fail. However, it will be argued that it is far from obvious that the account of Perceptual Intuitionism which emerges constitutes an independent alternative to other intuitionist accounts. This is because we have reason to think that ethical perceptual experience may be epistemically dependent on other epistemic sources, e.g. a priori intuition or emotion.     

Clarifying Ethical Intuitionism

In recent years there has been a resurgence of interest in Ethical Intuitionism, whose core claim is that normal ethical agents can and do have non‐inferentially justified first‐order ethical beliefs. Although this is the standard formulation, there are two senses in which it is importantly incomplete. Firstly, ethical intuitionism claims that there are non‐inferentially justified ethical beliefs, but there is a worrying lack of consensus in the ethical literature as to what non‐inferentially justified belief is. Secondly, it has been overlooked that there are plausibly different types of non‐inferential justification, and that accounting for the existence of a specific sort of non‐inferential justification is crucial for any adequate ethical intuitionist epistemology. In this context, it is the purpose of this paper to provide an account of non‐inferentially justified belief which is superior to extant accounts, and, to give a refined statement of the core claim of ethical intuitionism which focuses on the type of non‐inferential justification vital for a plausible intuitionist epistemology. Finally, it will be shown that the clarifications made in this paper make it far from obvious that two intuitionist accounts, which have received much recent attention, make good on intuitionism's core claim.     

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.     

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 an d 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.