Biomedical subjects

R E Graves

Publications and source records attributed to R E Graves.

23 records · Page 2Linked to original sources

PubMed1987

Measurement of the dichotic listening ear advantage for intersubject and interstimulus comparisons.

Conventional dichotic listening techniques can unquestionably be used for nominal (left vs. right) categorization of ear or hemispheric differences. These techniques cannot, however, be used for ordinal comparisons of the size of ear advantages among different subjects or different tasks if the measure of the size of the lateral asymmetry is confounded with effects of varying overall performance, attentional bias, or choice of laterality index. A psychophysical procedure is described which is designed to avoid these confounds by measuring discrimination ability, in decibels, as the interaural intensity difference (IID) required for a specific accuracy. Results from two experiments with right-handed subjects showed an average right-ear advantage of about 3 db for phoneme discrimination and an average left-ear advantage of the same size for intonation discrimination.

Adolescent↗

PubMed1987

Survey of calf and heifer housing on Pennsylvania dairy farms.

Research has established a link between calf and heifer housing and calf health. To determine current calf and heifer housing practices in Pennsylvania, 329 dairy farms were surveyed. The study was designed to increase awareness on the part of dairy farmers in housing and management and to develop education programs and materials in the area of calf and heifer management. All surveys were conducted on the farm by personal interviews. Results showed 24.9% of the farms had maternity pens in a building separate from the milking herd, although half of these farms used maternity pens in conjunction with facilities of lesser quality for the health and management of the animals. The same number of farms used calf hutches as those keeping calves in dairy barns with cows. A high percentage of the farms weaned calves (moved from milk diets to dry feed diets) to recommended types of facilities that included group pens, loose housing, and group or superhutches. However, 49.5% of the facilities used for weaned calves were in conjunction with other dairy animals. Animal restraint facilities have also been identified as an area that needs more emphasis on dairy farms. Many areas of dairy replacement housing on commercial dairy farms were determined to be unsatisfactory according to recommended Pennsylvania standards.

Animal Husbandry↗

PubMed1976

Are more items identified than can be reported?

Subjects are typically able to report only about four items from a many-item array presented tachistoscopically (full-report span). Current models of visual information processing disagree as to whether the limiting process is best represented as identification or as short-term memory. Estes and Taylor have argued that the number of items identified is up to twice the full-report span and, hence, that memory limits report. Experiment 1 here used a memory-probe method which showed that when no position report is required the large number of items that were identified in the Estes and Taylor paradigm is not greater than the number in a posticonic memory. Experiment 2 indicated that when position report is required the number of items identified (with correct position) does not exceed the number which can be reproduced in full report. These results support models in which memory is entailed by identification either as an aspect of the identification process or as a separate stage.

Cues↗

PubMedDate not supplied

Luminance and color effects on localization of briefly flashed visual stimuli.

Visual localization was studied by flashing small stimuli on a green background and requiring observers to press keys to indicate whether the stimulus appeared to the left or right of fixation. The results suggest that, for small (0.25 deg) briefly flashed (17 ms) stimuli at an eccentric location (10 deg), color contrast is not useable and localization presumably must rely on the magnocellular pathway. When stimulus size and duration were increased at 10-deg eccentricity, isochromatic stimuli could be localized at less than 10% luminance contrast (again suggesting use of the magnocellular high sensitivity luminance-contrast system), but isoluminant color-contrast stimuli could also be localized (suggesting use of the color-contrast sensitive parvocellular system). Thus, the results indicate that, dependent on stimulus conditions, both magnocellular and parvocellular pathways were utilized by normal observers in this localization task.

Adult↗

PubMedDate not supplied

Lateralized lexical decisions and the effects of hemifield masks: a study of interhemispheric inhibition and release.

A lateralized tachistoscope experiment using 40 normal, right-handed men tested the predictions of three different theories of interhemispheric interactions. Lexical decision for function words was measured for each visual field under several conditions of simultaneous stimulation in the contralateral hemifield. When a nonsense word was presented simultaneously to the contralateral hemifield, performance decreased, especially for words in the weaker field, an effect which is inconsistent with the predictions of the direct access model. When the contralateral nonsense word was immediately masked, there was a significant improvement in performance over the nonmasked condition. Analysis of the masking effect showed that the data are inconsistent with a callosal relay model, but are consistent with a model of transcallosal inhibition.

Adult↗