Biomedical subjects

M Schmitter-Edgecombe

Publications and source records attributed to M Schmitter-Edgecombe.

11 recordsLinked to original sources

PubMed2001

Acquisition of skilled visual search performance following severe closed-head injury.

This study used a semantic-category visual search task to investigate skill acquisition and automatic process development in a severe closed-head injured (CHI) population. Eighteen severe CHI participants (> I year post injury) and 18 matched controls completed over 3600 trials of training in both consistent mapping (CM) and varied mapping (VM) training situations. Transfer conditions were also used to test for development of an automatic attention response (AAR) that was independent of general, task-related learning. For both the severe CHI and control group, CM training, where individuals always responded in the same way to a specific class of stimuli, resulted in dramatic performance improvements and the development of an AAR. In the VM training condition, where individuals could not respond in the same way to a class of stimuli from one stimulus exposure to the next, there was little performance improvement and continued reliance on controlled processes. The visual search rates of the CHI participants also remained slower than those of controls following extended VM but not extended CM practice. These results indicate that skill acquisition training guidelines can be used to teach severe CHI patients to develop a new automatic skill.

Adult↗

PubMed2000

Intactness of inhibitory attentional mechanisms following severe closed-head injury.

Attentional problems are a common sequelae of closed-head injury (CHI). Research in the area of selective attention has pointed to the role of inhibitory mechanisms in the suppression of irrelevant information. In the current study, a negative priming paradigm was used to assess the inhibitory mechanisms of individuals suffering from a severe CHI. Twenty participants with severe CHIs (greater than 1 year postinjury) and 20 matched controls completed a negative priming task, as well as several other standardized tests of cognitive functioning. Within the negative priming task, 2 conditions were used to elicit information regarding facilitation by attended and ignored information and 1 condition was used to elicit inhibition of ignored information, as compared with a neutral control condition. Despite poorer performances on several tests of attention, there were no significant differences in the amount of inhibition displayed by the CHI participants as compared with the controls. Findings suggest that inhibitory processing deficits may not underlie the selective attention difficulties commonly seen following a severe CHI.

Adult↗

PubMed2000

Effects of divided attention on automatic and controlled components of memory after severe closed-head injury.

The relation between attention available at encoding and automatic and consciously controlled aspects of memory was investigated using the process-dissociation procedure. Twenty-four severely closed-head injured (CHI) participants (> 1 year postinjury) and 24 matched controls studied word lists in full- and divided-attention conditions. Recall cued with word stems was tested. In contrast to consciously controlled memory, the CHI group did not perform more poorly than the controls in estimates of automatic memory. Furthermore, for both groups, the divided-attention manipulation reduced the controlled estimates of memory, whereas automatic influences remained invariant. These results suggest that automatic memory processes may remain partially immune to the deleterious effects of severe CHI or show recovery by 1 year postinjury. They also indicate that automatic memory processes do not require additional attentional resources following severe CHI.

Adult↗

PubMed2000

Aging and word-finding: a comparison of spontaneous and constrained naming tests.

This study compared the word-finding abilities of 26 young adults (ages 18-22 years), 26 young-old adults (ages 58-74 years), and 26 old-old adults (ages 75-93 years) on a confrontational naming test (Boston Naming Test) and a more spontaneous discourse test. The groups were matched in terms of gender (7 male, 19 female) and estimated IQ (M = 114). When participants were asked to narrate what they perceived in pictures (discourse test), the older adult groups committed significantly more word-retrieval errors than the younger adults. In contrast, results from the picture-naming test surprisingly revealed higher naming accuracy by the older adult groups. Subsequent examination of the picture-naming items revealed that four items appeared to be influenced by generational familiarity with the item. These results suggest that selection of cohort-free items for picture-naming tests is important when comparing across age-groups, and that tests of discourse may be better measures for assessing everyday word-finding difficulties in healthy older adults.

Journal Article↗

PubMed1999

Effects of divided attention and time course on automatic and controlled components of memory in older adults.

The relation between attention available at encoding and automatic and consciously controlled aspects of memory was investigated within a single task using the process-dissociation procedure (L. L. Jacoby, 1991). Sixty-four older adults and 64 young adults studied a word list in either a full or a divided attention condition. Recall cued with word stems was tested immediately and at 20-minute and 60-minute delays. In contrast to consciously controlled influences of memory, automatic influences of memory (a) showed generally no reliable age differences, (b) remained invariant across the manipulation of attention, and (c) remained relatively invariant across the 60-minute time course. Furthermore, age did not interact with the attentional manipulation or the time course factor.

Adolescent↗

PubMed1999

Effects of divided attention on perceptual and conceptual memory tests: an analysis using a process-dissociation approach.

In two experiments, the nature of the relation between attention available at learning and subsequent automatic and controlled influences of memory was explored. Participants studied word lists in full and divided encoding conditions. Memory for the word lists was then tested with a perceptually driven task (stem completion) in Experiment 1 and with a conceptually driven task (category association) in Experiment 2. For recall cued with word stems, automatic influences of memory derived using the process-dissociation procedure remained invariant across a manipulation of attention that substantially reduced conscious recollection for the learning episode. In contrast, for recall cued with category names, dividing attention at learning significantly reduced the parameter estimates representing both controlled and automatic memory processes. These findings were similar to those obtained using indirect test instructions. The results suggest that, in contrast to perceptual priming, conceptual priming may be enhanced by semantic processing, and this effect is not an artifact of contamination from conscious retrieval processes.

Adult↗

PubMed1998

Visual selective attention after severe closed head injury.

This study investigated the nature of selective attention deficits after severe closed head injury (CHI). Twenty participants with severe CHI (greater than 1 year postinjury) and 20 matched controls completed search and nonsearch visual selective attention tasks under conditions of low (Experiment 1) and high (Experiment 2) target-distractor similarity. In the search situations, participants searched visual displays that contained 1, 4, or 8 items for the targets. In the nonsearch situations, the location of the targets was visually cued with a peripheral arrow. The results revealed that in both the low and high target-distractor similarity search conditions. CHI participants required a longer time than controls to locate and identify the target. In contrast, in the nonsearch condition, CHI participants were able to successfully ignore irrelevant task information when target-distractor similarity was low. However, when target-distractor similarity was high, CHI participants had more difficulty than controls ignoring the irrelevant information. These results suggest that, in comparison to controls, CHI participants may be at a disadvantage in selective attention situations when visual search is required and when the discriminability between targets and distractors is difficult.

Adult↗

PubMed1998

Ecological validity of neuropsychological tests: focus on the California Verbal Learning Test and the Wisconsin Card Sorting Test.

To date, few studies have assessed the ecological validity of current measures of memory and executive functioning, particularly the California Verbal Learning Test (CVLT) and the Wisconsin Card Sorting Test (WCST). A battery of tests, including the CVLT and the WCST, was administered to 28 severely head-injured adults who were 1 year or more postinjury. Hierarchical linear regression was performed to assess the relationship between these cognitive tests and work functioning while statistically controlling for physical disability, emotional distress, and memory compensation strategies utilized by the participants. Results suggest that the CVLT was best at predicting performance on the job; however, the CVLT and the WCST were about equally predictive of the type of position held by a participant. Hence, this study demonstrates the ecological validity of measures of memory and executive functioning for predicting work-related skills.

Journal Article↗

PubMed1997

Automatic process development following severe closed head injury.

Automatic process development was investigated in a closed head injury (CHI) population. Ten severe CHI participants (> 1 year postinjury) and 10 matched controls completed consistent mapping (CM) and varied mapping (VM) semantic-category memory search tasks. In VM search, despite a similar pattern of serial memory search, the CHI participants responded slower than controls and exhibited slower memory search rates throughout practice (1,800 trials). In CM search, after extensive practice (1,800 trials) both groups showed the performance characteristics indicative of automatic process development, that is, near-zero slopes and large reductions in response times. However, the CHI participants were slower to automatize the task. These results indicate that for memory-based search tasks the effects of a CHI may slow down the speed with which automatic processes develop but that CHI participants can acquire and use automatic processes in task performance.

Adult↗

PubMed1996

The effects of divided attention on implicit and explicit memory performance.

This study explored the nature of the relationship between attention available at learning and subsequent implicit and explicit memory performance. One hundred neurologically normal subjects rated their liking of target words on a five-point scale. Half of the subjects completed the word-rating task in a full attention condition and the other half performed the task in a divided attention condition. Following administration of the word-rating task, all subjects completed five memory tests, three implicit (category association, tachistoscopic identification, and perceptual clarification) and two explicit (semantic-cued recall and graphemic-cued recall), each bearing on a different subset of the list of previously presented target words. The results revealed that subjects in the divided attention condition performed significantly more poorly than subjects in the full attention condition on the explicit memory measures. In contrast, there were no significant group differences in performance on the implicit memory measures. These findings suggest that the attention to an episode that is necessary to produce later explicit memory may differ from that necessary to produce unconscious influences. The relationship between implicit memory, neurologic injury and automatic processes is discussed.

Adolescent↗

PubMed1995

Memory remediation after severe closed head injury: notebook training versus supportive therapy.

This study evaluated the effectiveness of a 9-week memory notebook treatment for closed-head-injured (CHI) participants with documented memory deficits. Eight participants who had sustained a severe CHI more than 2 years earlier were allocated to receive either notebook training or supportive therapy. Memory outcome indicators, which differed in sensitivity to detect everyday memory failures (EMFs), were administered before treatment, immediately after treatment, and at a 6-month follow-up. At posttreatment, the notebook training group reported significantly fewer observed EMFs on a daily checklist measure than the supportive therapy group. Although in the same direction, this finding no longer reached significance at follow-up. No significant treatment effects were found for the laboratory-based memory measures at posttreatment or follow-up. Although the present results are to be considered preliminary because of the small sample size, they suggest that notebook training has the potential to help individuals compensate for everyday memory problems and that the methods used to measure training efficacy are important.

Activities of Daily Living↗