Biomedical subjects

Mark A McDaniel

Publications and source records attributed to Mark A McDaniel.

16 recordsLinked to original sources

PubMed2006

Brain regions and their dynamics in prospective memory retrieval: a MEG study.

We measured brain activity using magnetoencephalography in five participants during ongoing tasks that included prospective memory, retrospective memory, and oddball trials. Sources were identified in the hippocampal formation and posterior parietal and frontal lobes. Posterior parietal cortex activation had an earlier onset in the prospective memory condition than retrospective memory or oddball conditions, a higher level of theta activity in the retrospective condition, and higher levels of upper alpha in the prospective and oddball conditions. Activation of the hippocampal formation had a longer duration in the retrospective memory and prospective memory conditions than the oddball condition, but prominent alpha and theta band activity was present in all three conditions. We interpret the early (87 ms) onset of activity in parietal cortex as evidence for an initial noticing of appropriate conditions for a PM response. Hippocampal activity may reflect a subsequent memory search for the intended action.

Adult↗

PubMed2006

The Cognitive Interview enhances long-term free recall of older adults.

The Cognitive Interview, a retrieval-based mnemonic technique, has received only limited attention in its application with older adults, and based on previous findings, its benefit to older adults is unclear. The authors found that the Cognitive Interview effectively increased older adults' recall relative to standard recall instructions at a 3-week delay. These findings demonstrate the benefit of a standardized (rather than the prototypically interactive) Cognitive Interview as applied to perceptually impoverished, text-based stimuli. Both theoretical and practical implications of the findings are discussed.

Aged↗

PubMed2005

Multiple processes in prospective memory retrieval: factors determining monitoring versus spontaneous retrieval.

Theoretically, prospective memory retrieval can be accomplished either by controlled monitoring of the environment for a target event or by a more reflexive process that spontaneously responds to the presence of a target event. These views were evaluated in Experiments 1-4 by examining whether performing a prospective memory task produced costs on the speed of performing the ongoing task. In Experiment 5, the authors directly tested for the existence of spontaneous retrieval. The results supported the multiprocess theory (M. A. McDaniel & G. O. Einstein, 2000) predictions that (a) spontaneous retrieval can occur and can support good prospective memory and (b) depending on task demands and individual differences, people rely to different degrees on monitoring versus spontaneous retrieval for prospective remembering.

Attention↗

PubMed2005

Apolipoprotein E and prospective memory in normally aging adults.

The epsilon4 allele of apolipoprotein E (APOE) is an established risk factor for Alzheimer's disease, despite uncertainty as to its effect on cognitive function in normal aging. Some evidence suggests poor episodic memory and executive functioning in epsilon4 allele carriers. Prospective memory has been overlooked in investigations of the relationship between APOE and cognition. The authors used a laboratory paradigm to examine the relationship between prospective memory and APOE status in healthy elderly adults, and they varied the association (high vs. low) between a target word and a response word. The authors found a significant deficit in prospective memory for epsilon4 allele carriers but no effect of association in either group. The results suggest the deficit was due to failure of the prospective component of the task.

Aged↗

PubMed2005

The bizarreness effect: dissociation between item and source memory.

The present study investigated the relationship between memory for particular items (nouns embedded in sentences) varying in bizarreness and the spatial location in which they were learned. Consistent with earlier findings, the items embedded in bizarre sentences were better recalled than those embedded in common sentences. This mnemonic advantage for bizarre sentences did not extend to memory for source (spatial location), which did not reliably vary as a function of bizarreness. This pattern is inconsistent with several existing theoretical formulations of the relation between item and source encoding and related findings. We propose a theoretical possibility for integrating these varied findings. Finally, the expectation-violation explanation of the bizarreness effect was not supported by the absence of a relation between recall of the items and memory for context.

Analysis of Variance↗

PubMed2005

Disentangling encoding versus retrieval explanations of the bizarreness effect: implications for distinctiveness.

Recall effects attributed to distinctiveness have been explained by both encoding and retrieval accounts. Resolution of this theoretical controversy has been clouded because the typical methodology confounds the encoding and retrieval contexts. Using bizarre and common sentences as materials, we introduce a paradigm that decouples the nature of the encoding context (mixed vs. unmixed lists of items) from the retrieval set (mixed vs. unmixed retrieval sets). Experiment 1 presented unmixed lists for study, and Experiment 2 presented mixed lists for study. In both experiments, significant bizarreness effects were obtained in free recall when the retrieval set intermixed items but not when the retrieval set consisted of only one item type. Also, Experiment 1, using a repeated testing procedure, did not reveal evidence for more extensive encoding of bizarre sentences than of common sentences. The results support the idea that retrieval dynamics primarily mediate the bizarreness effect, and perhaps more generally, distinctiveness effects.

Affect↗

PubMed2005

The conceptual basis of function learning and extrapolation: comparison of rule-based and associative-based models.

The purpose of this article is to provide a foundation for a more formal, systematic, and integrative approach to function learning that parallels the existing progress in category learning. First, we note limitations of existing formal theories. Next, we develop several potential formal models of function learning, which include expansion of classic rule-based approaches and associative-based models. We specify for the first time psychologically based learning mechanisms for the rule models. We then present new, rigorous tests of these competing models that take into account order of difficulty for learning different function forms and extrapolation performance. Critically, detailed learning performance was also used to conduct the model evaluations. The results favor a hybrid model that combines associative learning of trained input-prediction pairs with a rule-based output response for extrapolation (EXAM).

Animals↗

PubMed2004

Suppressing irrelevant information: knowledge activation or inhibition?

In 3 experiments, the authors examined the role of knowledge activation in the suppression of contextually irrelevant meanings for ambiguous homographs. In Experiments 1 and 2, participants with greater baseball knowledge, regardless of reading skill, more quickly suppressed the irrelevant meaning of ambiguous words in baseball-related, but not general-topic, sentences. Experiment 3 demonstrated that participants with greater general knowledge, regardless of reading skill, more quickly suppressed the irrelevant meaning of the ambiguous words in general-topic sentences. As predicted by D. S. McNamara's (1997) knowledge-based account of suppression, ambiguity effects are influenced by greater activation of knowledge related to the intended meaning of the homograph. These results challenge inhibition (e.g. M. A. Gernsbacher, K. R. Varner. & M. Faust, 1990) as the sole mechanism responsible for the suppression of irrelevant information.

Attention↗

PubMed2004

Cue-focused and reflexive-associative processes in prospective memory retrieval.

Several theories of event-based prospective memory were evaluated in 3 experiments. The results depended on the association between the target event and the intended action. For associated target-action pairs (a) preexposure of nontargets did not reduce prospective memory, (b) divided attention did not reduce prospective memory, (c) prospective memory was better than when the target event and intended action were not associated, and (d) prospective memory was characterized by retrieval of the precise intended action. These results converge on the view that retrieval is mediated by a reflexive-associative process. In contrast, for unassociated pairs (a) preexposure of nontargets reduced prospective memory, and (b) divided attention reduced prospective memory. These results implicate cue-focused retrieval processes and are most consistent with a discrepancy-plus-search model. The entire pattern implicates both cue-focused and reflexive-associative processes and more generally supports a multiprocess framework of prospective memory (M. A. McDaniel & G. O. Einstein, 2000).

Association↗

PubMed2004

Importance effects on performance in event-based prospective memory tasks.

In the present study we manipulated the importance of performing two event-based prospective memory tasks. In Experiment 1, the event-based task was assumed to rely on relatively automatic processes, whereas in Experiment 2 the event-based task was assumed to rely on a more demanding monitoring process. In contrast to the first experiment, the second experiment showed that importance had a positive effect on prospective memory performance. In addition, the occurrence of an importance effect on prospective memory performance seemed to be mainly due to the features of the prospective memory task itself, and not to the characteristics of the ongoing tasks that only influenced the size of the importance effect. The results suggest that importance instructions may improve prospective memory if the prospective task requires the strategic allocation of attentional monitoring resources.

Adult↗

PubMed2004

Age differences in veridical and false recall are not inevitable: the role of frontal lobe function.

The relationship of neuropsychological measures of frontal lobe function to age differences in false recall was assessed using the Deese/Roediger-McDermott associative false memory paradigm (Deese, 1959; Roediger & McDermott, 1995). As other studies have found, older adults were less likely to correctly recall studied items and more likely to falsely recall highly related but nonpresented items than were younger adults. When older adults were divided based on a composite measure of frontal lobe functioning, this age difference was found only for low frontal lobe functioning individuals. High frontal lobe functioning older adults and young adults had equivalent levels of false recall, as well as equivalent levels of veridical recall. These results suggest that age differences in memory may be due to declines in frontal lobe function. More important, our findings indicate that declines in veridical recall and increases in false recall are not an inevitable consequence of aging.

Adult↗

PubMed2003

Aging and maintaining intentions over delays: do it or lose it.

When execution of retrieved intentions must be briefly delayed, older adults display deficits in performing those intentions (G. O. Einstein, M. A. McDaniel, M. Manzi, B. Cochran, & M. Baker, 2000). This initial finding was extended by showing age-related deficits with 5-s unfilled delays, with instructions to rehearse during the delay, and with divided attention during initial retrieval of the intention. Performance increased with a break at the end of the delay period, such that when combined with full attention (during retrieval), older adults' performance approached that of younger adults. These results suggest that age compromises maintenance of information in awareness. Consequently, when forced to delay execution of retrieved intentions, older adults may rely more on plan reformulation and subsequent retrieval of the intention from long-term memory at the end of the delay.

Adolescent↗

PubMed2003

Forgetting of intentions in demanding situations is rapid.

Demanding work settings often require the deferral of intended actions. In 3 experiments, participants were to withhold a response until they encountered a task change (which occurred 5, 15, or 40 sec later). To approximate highly demanding settings, the experimenters sometimes divided attention during the delay period. During some of the delays the experimenters interrupted the participants with an additional task (Experiment 1). Demanding conditions as well as interruptions revealed rapid forgetting of intentions at levels that would be considered significant in applied settings. Experiments 2 and 3 showed that this rapid forgetting was not reduced by strategic rehearsal and implementation intention strategies. The results suggest that maintaining intentions over brief delays is not a trivial task for the human cognitive system.

Attention↗

PubMed2003

The fruitfulness of a nomothetic approach to investigating AAC: comparing two speech encoding schemes across cerebral palsied and nondisabled children.

The observation that typical users of augmentative and alternative communication (AAC) systems vary widely in their characteristics raises issues about the utility of a nomothetic approach for investigating and evaluating important variables, as well as about the value of studying children without disabilities to contribute to the understanding of AAC systems. To provide an initial basis for examining the fruitfulness of the nomothetic approach, the effects of 2 fundamental variables, number of display levels (single vs. dual) and vocabulary abstractness (concrete vs. abstract words), on vocabulary acquisition were examined for children without disabilities and for speech impaired children with cerebral palsy (CP). Children demonstrated the same pattern of acquisition, regardless of disability status. Both groups of children made more errors on the dual-level display than on the single-level display and made more abstract errors than concrete errors. Importantly, the performance of individuals consistently conformed to group performance. These findings suggest that a nomothetic research approach that includes results of children without disabilities can usefully illuminate consequences of important variables in AAC systems. Clinical implications based on these findings were also discussed.

Cerebral Palsy↗

PubMed2002

Revisiting the picture-superiority effect in symbolic comparisons: do pictures provide privileged access?

In 4 experiments, symbolic comparisons were investigated to test semantic-memory retrieval accounts espousing processing advantages for picture over word stimuli. In Experiment 1, participants judged pairs of animal names or pictures by responding to questions probing concrete or abstract attributes (texture or size, ferocity or intelligence). Per pair, attributes were salient or nonsalient concerning their prerated relevance to animals being compared. Distance (near or far) between attribute magnitudes was also varied. Pictures did not significantly speed responding relative to words across all other variables. Advantages were found forfar attribute magnitudes (i.e., the distance effect) and salient attributes. The distance effect was much less for salient than nonsalient concrete-attribute comparisons. These results were consistently found in additional experiments with increased statistical power to detect modality effects. Our findings argue against dual-coding and some common-code accounts of conceptual attribute processing, urging reexamination of the assumption that pictures confer privileged access to long-term knowledge.

Analysis of Variance↗

PubMedDate not supplied

"Brain-specific" nutrients: a memory cure?

OBJECTIVE: We review the experimental evaluations of several widely marketed nonprescription compounds claimed to be memory enhancers and treatments for age-related memory decline. We generally limit our review to double-blind placebo-controlled studies. The compounds examined are phosphatidylserine (PS), phosphatidylcholine (PC), citicoline, piracetam, vinpocetine, acetyl-L-carnitine (ALC), and antioxidants (particularly vitamin E). RESULTS: In animals, PS has been shown to attenuate many neuronal effects of aging, and to restore normal memory on a variety of tasks. Preliminary findings with humans, though, are limited. For older adults with probable Alzheimer's disease, a single study failed to demonstrate positive effects of PS on memory performance. For older adults with moderate cognitive impairment, PS has produced consistently modest increases in recall of word lists. Positive effects have not been as consistently reported for other memory tests. There is one report of consistent benefits across a number of memory tests for a subset of normal adults who performed more poorly than their peers at baseline. The choline compounds PC and citicoline are thought to promote synthesis and transmission of neurotransmitters important to memory. PC has not proven effective for improving memory in patients with probable Alzheimer's disease. The issue remains open for older adults without serious degenerative neural disease. Research on citicoline is practically nonexistent, but one study reported a robust improvement in story recall for a small sample of normally aging older adults who scored lower than their peers in baseline testing. Animal studies suggest that piracetam may improve neuronal efficiency, facilitate activity in neurotransmitter systems, and combat the age-related decrease in receptors on the neuronal membrane. However, for patients with probable Alzheimer's disease, as well as for adults with age-associated memory impairment, there is no clear-cut support for a mnemonic benefit of piracetam. Vinpocetine increases blood circulation and metabolism in the brain. Animal studies have shown that vinpocetine can reduce the loss of neurons due to decreased blood flow. In three studies of older adults with memory problems associated with poor brain circulation or dementia-related disease, vinpocetine produced significantly more improvement than a placebo in performance on global cognitive tests reflecting attention, concentration, and memory. Effects on episodic memory per se have been tested minimally, if at all. ALC participates in cellular energy production, a process especially important in neurons, and in removal of toxic accumulation of fatty acids. Animal studies show that ALC reverses the age-related decline in the number of neuron membrane receptors. Studies of patients with probable Alzheimer's disease have reported nominal advantages over a range of memory tests for ALC-treated patients relative to placebo groups. Significant differences have been reported rarely, however. Whether ALC would have mnemonic benefits for aging adults without brain disease is untested as far as we know. Antioxidants help neutralize tissue-damaging free radicals, which become more prevalent as organisms age. It is hypothesized that increasing antioxidant levels in the organism might retard or reverse the damaging effects of free radicals on neurons. Thus far, however, studies have found that vitamin E does not significantly slow down memory decline for Alzheimer's patients and does not produce significant memory benefits among early Parkinson's patients. Neither did a combination of vitamins E and C significantly improve college students' performance on several cognitive tasks. CONCLUSIONS: In sum, for most of the "brain-specific" nutrients we review, some mildly suggestive effects have been found in preliminary controlled studies using standard psychometric memory assessments or more general tests designed to reveal cognitive impairment. We suggest that future evaluations of the possible memory benefits of these supplements might fruitfully focus on memory processes rather than on memory tests per se.

Acetylcarnitine↗