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Biomedical subjects

W A Rogers

Publications and source records attributed to W A Rogers.

At least 19 recordsLinked to original sources
PubMed1992

General slowing alone cannot explain age-related search effects: reply to Cerella (1991)

Cerella (1991) has argued that the performance of older adults in the Fisk and Rogers (1991) study is a linear function of the performance of younger adults that is independent of task-specific cognitive requirements. We demonstrate that this is not the case. First, we show that the scatter plot analyses used by Cerella can hide the very task-specific age-related slowing they were designed to reveal. Second, we demonstrate that the percentage of variance explained by such analyses can be misleading. Third, we show that there are reliable differences across tasks in the parameters relating younger and older adults' performance. Finally, we argue that the general, task-independent proportionate slowing that Cerella suggested explains so much of the variance in age-related performance is actually an average slowing that is a function of a relatively small task-independent and a relatively large task-dependent factor.

Adult↗
PubMed1992

Age differences in visual search: target and distractor learning.

Age differences in a semantic category visual search task were investigated to determine whether the age effects were due to target learning deficits, distractor learning deficits, or a combination thereof. Twelve young (mean age 20) and 12 older (mean age 70) adults received 2,400 trials each in consistent and varied versions of the search task. Following training, a series of transfer-reversal manipulations allowed the assessment of target learning and distractor learning both in isolation and in combination. The pattern of data suggests that older adults have a deficit in their ability to increase the attention-attraction strength of targets and to decrease the attention-attraction strength of distractors. The results are interpreted in terms of a strength-based framework of visual search performance.

Adult↗
PubMed1991

Communicating patients' esthetic needs to the dental laboratory.

A visual aid in the form of a lined transparent plastic screen is attached to an earbow type of facebow and placed on the face. The screen can be adjusted to several horizontal tilts from the horizontal aspect in a clockwise or counterclockwise direction. The screen helps the dentist visualize horizontal and vertical facial characteristics that facilitate alignment of anterior restorations. This information can be sent to the laboratory, which can interpret the data with a smaller version of the adjustable screen.

Communication↗
PubMed1991

Are age differences in consistent-mapping visual search due to feature learning or attention training?

In this experiment, the ability of young and old adults to differentially modify the attention-attraction strength of targets and distractors relative to feature differentiation was examined. Eight young and 8 old subjects were trained for 8,000 trials in conditions that allowed maximal target-distractor strength differentiation, inhibited target-distractor strength differentiation but facilitated feature differentiation, or inhibited both target-distractor strength differentiation and feature differentiation. Age-related performance was assessed between and within conditions during training and with reversal conditions where the roles of targets and distractors were switched. The pattern of data during training and at reversal supports the proposal that age differences in extended-practice visual search are due to differences in the ability to differentially strengthen targets and distractors.

Adult↗
PubMed1991

Toward an understanding of age-related memory and visual search effects.

Young and old Ss were tested in 3 experiments conducted to explore factors leading to age-related performance differences in consistent mapping (CM) and varied mapping (VM) search tasks. The separate and combined influences of memory scanning and visual search on age-related search effects were examined. In both CM letter and CM semantic category search, age interacted with comparison load in visual and hybrid memory-visual search conditions, whereas differential age effects were not present in pure memory search. For VM search, age effects were present only in pure memory search. These data support the view that the separation of type of search training (CM and VM) as well as memory and visual search components is critical for predicting age-related performance differences. The dissociation of the pattern of age effects in memory and visual search suggests that memory and visual search involve different processing mechanisms.

Adult↗
PubMed1991

Age-related differences in the maintenance and modification of automatic processes: arithmetic Stroop interference.

This experiment was designed to investigate whether well-learned "automatic" processes remain stable as a function of age, as well as to determine whether the ability to modify these automatic processes is disrupted for older adults. We used an arithmetic Stroop task to measure the stability of an automatic process. Nineteen young (mean age 22) and 19 old (mean age 75) adults participated in three experimental sessions, each of which consisted of 15 blocks of 30 trials. Although the young subjects had faster verification times overall than did the old adults, both young and old subjects showed significant interference effects. For the young adults, there was a decrease in the interference effect with practice, which suggested that they were learning to inhibit the automatic process of performing the arithmetical operation. However, the old adults showed no significant decrease in the associative interference effects. This implies that the older adults were impaired in their ability to inhibit automatic processes, even when those processes interfered with performance. Theoretical and practical training implications are discussed.

Adult↗
PubMed1991

Recombination of automatic processing components: the effects of transfer, reversal, and conflict situations.

This research was conducted to evaluate the effects of compatible and incompatible automatic processes on performance. Subjects were trained for 8400 trials of consistent mapping practice in a semantic category visual search task and then transferred for 2352 trials to conditions that utilized the trained component processes in various ways. Results indicate that if the components were reused in a compatible fashion (target and distractor transfer), there was positive transfer. Target and distractor reversal resulted in equivalent and severe performance disruption that persisted for the entire retraining period. Target conflict produced disruption equivalent to the reversal conditions. Distractor conflict resulted in less initial disruption, which dissipated before the end of the retraining period. The results are discussed in terms of agreement with strength-theoretic views of visual search and in terms of practical training and retraining issues.

Adult↗
PubMed1990

Consistent and varied memory/visual search: is there an interaction between age and response-set effects?

Interactions of stimulus consistency and response-set were examined after extensive consistent (CM) and varied mapping (VM) practice for young (mean age 20) and old (mean age 74) adults. The experiment examined whether reduced response complexity would lead to equivalent consistent mapping search performance across age groups. Subjects received 2,240 training trials each for CM and VM versions of a hybrid memory/visual search task. During training two response conditions were used: (1) respond only when a target was present (Yes-only responding) and (2) respond only when a target was absent (No-only responding). Following initial training, subjects were transferred to the opposite response condition. During training the function relating reaction time to memory-set size differed between age groups only with CM practice, replicating age-related effects previously found for extensive CM practice. Response reversal (e.g., Yes-only to No-only) after training led to age-related transfer effects for both CM and VM search. Importantly, the transfer data suggest age-dependent controlled processing effects.

Adolescent↗
PubMed1988

Interaction of bass tapeworm, Proteocephalus ambloplitis, and Neoechinorhynchus sp. (Acanthocephala) in largemouth bass, Micropterus salmoides.

The number of plerocercoids of the bass tapeworm, Proteocephalus ambloplitis, in wild largemouth bass was negatively correlated (r = -0.94) with the number of Neoechinorhynchus sp. Competitive inhibition between the 2 parasites appeared to exist. Similarly, the numbers of Neoechinorhynchus sp. in wild bass decreased when adult bass tapeworms were present in the intestine. Proteocephalus ambloplitis plerocercoids used to challenge bass vaccinated with either P. ambloplitis adult or Neoechinorhynchus sp. antigens were smaller (P less than 0.05) when recovered than those used to challenge control bass. Based on preliminary results, both antigens might have enabled the bass to limit growth and/or development of the invading bass tapeworm, plerocercoids. Cross-protective immunity may be the reason for this occurrence, in which case, it could offer an explanation for competitive inhibition existing between P. ambloplitis and Neoechinorhynchus sp.

Acanthocephala↗
PubMed1987

Plasma amino acid analysis in dogs with experimentally induced hepatocellular and obstructive jaundice.

Plasma amino acid concentrations were determined weekly for 4 weeks in 6 sham-operated control dogs, in 6 sham-operated dogs after induction of liver disease with dimethylnitrosamine (DMNA), and in 6 dogs after surgical ligation of the common bile duct. Results were compared with standard biochemical indices of liver function and with histologic changes in serial liver biopsy specimens. Concentrations of most amino acids increased after 2 weeks in DMNA-treated dogs, whereas they were normal or decreased in bile duct-ligated dogs. With increasing severity of the liver disease, the molar ratio (normal mean +/- SEM = 3.48 +/- 0.14) in DMNA-treated dogs decreased to 2.42 +/- 0.19 by 2 weeks and to 1.17 +/- 0.09 by 4 weeks. The ratio remained normal in bile duct-ligated dogs. Molar ratio and aromatic amino acid concentrations correlated better with hepatic necrosis and inflammation than did standard biochemical indices (eg, bilirubin, liver enzymes). Therefore, plasma amino acid analysis and determination of the molar ratio may be useful in the differential diagnosis of hepatocellular and obstructive jaundice in dogs. A decrease in the molar ratio may reflect portal hypertension and hepatocellular disease.

Alanine Transaminase↗
PubMed1979

Electromyographic and esophagomanometric findings in clinically normal dogs and in dogs with idiopathic megaesophagus.

Electromyography of 12 clinically normal dogs and 7 dogs with idiopathic megaesophagus revealed trains of positive sharp waves in the muscles of facial expression and in the lingual muscles of both groups. Positive waves are usually indicative of motor-unit disease; however, they are clinically insignificant in these muscles. Positive sharp waves were detected in the esophageal muscle of one dog with congenital megaesophagus. Esophageal electromyograms obtained in a dog with congenital megaesophagus and in 2 clinically normal dogs were normal. Resting caudal esophageal sphincter pressure was similar in both clinically normal dogs (mean, 22.3 mm of Hg; range, 15--37 mm of Hg) and in dogs with congenital or acquired idiopathic megaesophagus (mean, 29.6 mm of Hg; range, 20--50 mm of Hg).

Animals↗