PubMed Health⌕ Search

Biomedical subjects

T M Nelson

Publications and source records attributed to T M Nelson.

At least 19 recordsLinked to original sources
PubMed1999

Improving perception of letters and visual structure of language.

Information about letters and the physical structure of language printed in Roman characters was given to children beginning to read. Experimental investigations coupled three alternative graphic modes of printing upper- and lower-case letters with an instructional intervention termed "Alpha-Beta" which provides practice in letter sorting, matching of letters, associative matching, and memory matching. In respect to graphics, Mode A letters were in standard alphabet form. Mode B provided standard letters with each backed by a unique half-tone (Visually Stippled Alphabet); Mode C provided standard letters with each backed by a unique visual texture (Visually Patterned Alphabet). Pre-posttest change in reading readiness was measured using the Metropolitan Readiness Test. In the first study 224 English-speaking 5- to 6-yr.-old children were tested. In the second there were 158 Spanish-speaking girls and boys 6 to 7 years old. It was predicted that Alpha-Beta intervention involving visually patterned alphabet would lead to the greatest increases in readiness scores. This is confirmed in both studies for children low in reading readiness preexperiment. Children high in reading readiness are less affected. The second experiment involved Spanish-speaking children and investigated intervention by Alpha-Beta against a no-intervention control. This confirms the value of Alpha-Beta per se. Possible explanations for the improvements are identified.

Child↗
PubMed1997

Fatigue, mindset and ecology in the hazard dominant environment.

Ratings made by 47 experienced drivers to 18 items of a Fatigue Advisory are highly consistent. Every item is rated 'very' or 'extremely important' to the safety of inexperienced drivers. In contrast, 'adequacy of knowledge' about fatigue is rated consistently lower. This inconsistency may reflect a culturally based confusion about fatigue. Education and public awareness campaigns need to emphasize that 'immoderate indulgence of driving' is as dangerous to safety as 'immoderate indulgence of alcohol'. A basic challenge is to improve understanding of the manner in which the experience of fatigue emerges during driving. Study of perceptual/cognitive manifestations aided by operational definition of fatigue as a 'declarative state' renders driving fatigue a definite observable subjective condition arising from continuous operation of a vehicle. Specific cognitive symptoms of fatigue such as boredom, tiredness, inattention, etc. emerging with driving fatigue, are circumscribed within the activity of driving itself and also reflect the particular conditions in which driving fatigue occurs. This approach reveals ecological dimensions to the problem. The specific experiences of driving fatigue are seen to emerge as a function of the driver environment relationship in a particular driving environment. It is suggested that the concept of the 'hazard dominant environment' and the compensating landscape perceptions of 'prospect' and 'refuge' proposed by Appleton [(1995) The Experience of Landscape. Wiley, London] in concert with the concept of environmental 'affordances' provided by Gibson [(1979) An Ecological Approach to Visual Perception. Houghton Mifflin, Boston] open promising possibilities for improving environmental education about driving fatigue.

Accidents, Occupational↗
PubMed1997

Development of fatigue symptoms during simulated driving.

Why do people sometimes allow themselves to be overcome by fatigue? Ancient human survival may have depended on ignoring fatigue. Its modern occurrence in the absence of strain may further render us insensitive to its warning value. To test whether deliberate monitoring of certain symptoms may help drivers and other workers realize when they need to rest to avoid hazard, the development of fatigue while driving a simulator was objectively measured in terms of how many persons quit driving as a function of time. Some subjects asked to stop after 90 minutes; others lasted 240 minutes. Grouping data from an adapted Pearson [(1957) Journal of Applied Psychology, 44, 186-191] fatigue checklist revealed a curious phenomenon. No matter how long subjects drove before wanting to quit, they still developed much the same subjective level of fatigue at the end. This suggests that people do not differ greatly in how much fatigue they can tolerate but rather how quickly they reach a certain critical level of fatigue. Averaging fatigue scores backwards from the time subjects quit produced a function similar to the quitting function. Similar treatment of the other data revealed certain clusters of symptoms whose development also paralleled the development of fatigue.

Adolescent↗
PubMed1996

The effect of dietary selenium deficiency on acute colorectal mucosal nucleotoxicity induced by several carcinogens in the rodent.

BACKGROUND: Selenium (SE) has been inversely associated with colon cancer risk. Two potential mechanisms of this effect were examined in a rodent short-term carcinogenesis assay: whether dietary SE deficiency altered the initiation aspect of carcinogenesis in the colon, and whether SE altered carcinogen metabolism. SETTING: Animal laboratory. SUBJECTS: 52 Sprague-Dawley rats, divided into a SE diet deficient group (0.002 parts per million; ppm) and a SE sufficient (0.2 ppm) group. ENDPOINTS: Weight, serum SE concentration, and karryorhectic index (KI), which is a measure of acute carcinogen induced nuclear toxicity in the colonic mucosa. METHODS: After three weeks of acclimation to the diets, eight animals from each dietary group were injected with one of the following: dimethylhydrazine (DMH), a colon specific carcinogen, its metabolite, methylazoxymethanol (MAM), or 0.9% sodium chloride. Twenty-four hours after injection the colons were removed, blood drawn, and the stained colons assayed for nuclear aberrations. RESULTS: No weight differences were generated by the dietary variations. Low-dietary SE resulted in serum SE declining markedly in the study period to 6 ng/ml versus 33 ng/ml in the SE sufficient group. Diet alone, and variations in weight gain, did not alter the KI. Both carcinogens greatly increased the KI in both the left and right colon. A SE-deficient diet was associated with a higher KI in both carcinogen groups in the right colon, with statistical significance for both the left and right colon in the MAM injection group. CONCLUSIONS: Dietary SE deficiency is associated with increased KI of the colon in MAM treated rats. SE, therefore, has a protective effect in the initiation phase of carcinogenesis.

Animals↗
PubMed1995

Perineal sigmoidectomy for sigmoid procidentia: report of a case.

Although rectal procidentia is not an uncommon disease, presentation of more proximal segments of the large bowel through the anus is extremely rare. We report a male patient with an acute sigmoid prolapse secondary to a large villous adenoma acting as the lead point. Since the prolapsed segment was irreducible and exhibited signs of vascular compromise, an intraoperative colonoscopy and perineal sigmoidectomy with a primary anastomosis was carried out. Postoperatively, the patient did well and was discharged 5 days after his operation. Recognition of the difference between sigmoid and rectal procidentia should influence the surgeon's choice of operation, along with the viability of the prolapsed bowel and overall condition of the patient.

Adenoma, Villous↗
PubMed1993

Factors affecting perception of outdoor public environments.

Comfort and related perceptions are important in respect to use of outdoor public places. In a laboratory, 170 persons viewed four such places on slides and rated them on 10 dimensions, namely, "comfortable," "playful," "serious," "active," "unsafe," "good," "tense," "interesting," "gloomy," and "pleasing." Instructions were used to vary time of day and the number of people present at the location. It was found that women (n = 96) regard outdoor environments as more threatening than do men (n = 74) which suggests that women feel more vulnerable to untoward acts and that public places are rated less desirous at dusk than at dawn, presumably because dusk is followed by night and dawn by day. It was also discovered that such public environments are rated better than deserted places when occupied by two or more persons. Some of these results are consistent with the Prospect-Refuge Theory of Appleton.

Adult↗
PubMed1991

Self-perception of the ability to work in the cold.

Accumulating evidence of beneficial effects from physical exertion must be balanced against increased risk of cardiac arrest during performance. There is evidence that, by using such cues as heart rate, individuals can monitor their level of exertion perceptually. We undertook experiments to discover whether temperature and heart rate interact to affect self-perception when the effective temperature is moved downard from the comfort zone. In the first pilot study, 36 males practiced a new game, SwedeBall, for a period of 20 minutes. Twelve were randomly assigned to play at a temperature of 22 degrees C, another 12 to play at 0 degrees C, and the remaining 12 to play at -7 degrees C. The players showed tendencies toward an overall improvement in self-evaluations after brief practice, with more favorable responses when the temperatures were lower. In a second experiment on different days, 8 men pedaled a standard bicycle mounted as a wind trainer in a controlled environment chamber where the effective temperature was set at 26 degrees C, 8 degrees C, or -10 degrees C. The first 5-minute ride at each temperature was at a heart rate of 120 beats per minute (bpm), the second at 140 bpm, and a third at 160 bpm. We measured ratings of perceived effort (RPE), thermal impression, discomfort, perceived rate of speed, and projected endurance. The result confirmed that RPE was lowered by temperature when heart rate was constant. The data also showed that the lowered temperatures uniformly produced more favorable self-perceptions on the other four scales. The outcome is related to physiological problems that might arise when temperature depresses heart rate and reduces the experience of effort.

Acclimatization↗
PubMed1990

Comparing headphone and speaker effects on simulated driving.

Twelve persons drove for three hours in an automobile simulator while listening to music at sound level 63dB over stereo headphones during one session and from a dashboard speaker during another session. They were required to steer a mountain highway, maintain a certain indicated speed, shift gears, and respond to occasional hazards. Steering and speed control were dependent on visual cues. The need to shift and the hazards were indicated by sound and vibration effects. With the headphones, the driver's average reaction time for the most complex task presented--shifting gears--was about one-third second longer than with the speaker. The use of headphones did not delay the development of subjective fatigue.

Adult↗
PubMed1989

Application of automated human voice delivery to warning devices in an intensive care unit: a laboratory study.

Environmental concerns about the delivery of warning messages in intensive care units exist in the belief that conventional non-verbal alarm signals are perceived to be threatening by some patients. There is also a significant opportunity for error in interpretation by fatigued or anxious personnel. A laboratory study was undertaken to determine whether human subjects made fewer errors when messages regarding ICU related tasks were delivered by tape recorded human voice than by the non-verbal signals derived from devices in the ICU. Results demonstrated a statistically significant superiority of human voice messages over non-verbal signals. It is concluded that taped human voice messages merit field trials in intensive care units.

Computer Systems↗
PubMed1989

Contributions to the history of psychology: LX. Remarks about S. Howard Bartley, as a scholar, scientist, and human being.

The scholarly record of S. Howard Bartley (1902-1988) evokes respect because it shows quality, diversity, and quantity. Bartley's publications are well known and have been frequently cited in the literature of psychology, physiology, and optometry. His contributions to encyclopedias, handbooks, and other summative records of knowledge are legion. Notwithstanding his acknowledged eminence, unusual factors in his early upbringing worked to limit ability to gain full recognition for his work. Acting as a person, Bartley exhibited major talent in artistic areas and created endless delights for friends and colleagues in work and social settings.

History, 20th Century↗
PubMed1988

Affective responses to commercial and experimental auditory alarm signals for anaesthesia delivery and physiological monitoring equipment.

The affective response of subjects to the sounds of commercial and experimental auditory alarm signals was tested using a standard experimental protocol for measuring mood states and changes. Both types of signal evoked affective response. The commercial signals, however, evoked more response than the experimental signals, and that response was more negative in affect. A subset of the experimental signals, distinguished by specific acoustic characteristics, evoked particularly low levels of affect. The implications of low-affect alarms for the operating room are discussed.

Adult↗
PubMed1981

Delayed monochromatic hue matches indicate characteristics of visual memory.

Short-term memory for 16 monochromatic hues from 425 to 640 nm was measured after six delays from .1 to 24.3 sec by means of an iterative, momentary stimulus-matching technique. Small shifts were revealed in the remembered hue produced by certain wavelengths at some delays. These shifts did not follow trends consistent with a storage dependent on sensory pathway characteristics, perceptually unique hues, or semantic encoding but may reflect entropic effects in a storage that is remarkably unbiased. By indicating the discriminability of hues in memory, standard deviations of the delayed matches reveal other characteristics of what is stored: Their smooth, exponential growth questions the existence of "levels" and permits estimating the half-life of hue memory; their continued resemblance to the discrimination function for simultaneously perceived hues suggests that the stored activity; closely resembled the sensory response of color. The results also indicate how successive comparisons may be corrected in applied color work.

Adult↗
PubMed1980

Using Angels and Devils: a board game developed for play in nursing homes.

The incidence of perceptual deprivation and social isolation effects, possible correlates of such effects, and the potential for remediation of effects was studied for thirty-two nursing home residents through playing a discussion-stimulating board game called Angels and Devils. Results indicate a high incidence of sensory deprivation and social isolation effects in the population, as measured by resident response to questionnaire items. These do not correlate with length of institutionalization, amount of social contact, or degree of medical restriction, and may be reduced by stimulating resident-staff discussion. Findings are interpreted as indicating the need for more research in application of board games to ameliorate negative effects emerging in institutional environments.

Communication↗
PubMed1979

Perceptions of fatigue as related to alcohol ingestion.

An experiment is reported in which the role of alcohol in the emergence of fatigue was studied. Eleven (11) participants were requested to operate a driver trainer until they found the task too adverse to continue under conditions of high blood alcohol (BACL greater than 0.08%), low blood alcohol (BACL less than 0.08%), and no blood alcohol. Skill and heart rate were monitored and any personal distresses or observations made about performance were reported to an experimenter who acted in the role of 'passenger'. Results show decline in endurance as blood alcohol increases, but that a higher level of personal distress is endured by drivers who have imbibed, as compared to those who have not. Systematic discrepancies occur between the impressions gained by the experimenter (passenger) from verbal reports made by the driver, and the kinds of self-ratings drivers provide. Features of fatigue are analyzed theoretically as perceptual phenomena as related to alcohol and accidents.

Alcohol Drinking↗