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Biomedical subjects

G Underwood

Publications and source records attributed to G Underwood.

34 records · Page 2Linked to original sources
PubMed1983

Parafoveal words are effective in both hemifields: preattentive processing of semantic and phonological codes.

What effect may an unattended word have during a single fixation? Attention was selectively directed to a word exposed for 50 ms by the demand to make a rapid lexical decision response, and during the same presentation a second word was displayed approximately 2.3 deg of visual angle away on the same horizontal axis. The second word was backwards and forwards masked by a random-dot display, and was described to subjects as a distractor which was to be ignored. Although no response was required to this word, it was found to influence response latency to the attended word according to the semantic relationship which existed between the two. They interfered with the lexical decision response when the two words were related in meaning and also when they sounded as if they were related in meaning. These effects argue for automatic processing of the meaning of printed words presented in either visual hemifield, and for their automatic phonological activation.

Attention↗
PubMedDate not supplied

Eye fixations predict reading comprehension: the relationships between reading skill, reading speed, and visual inspection.

This experiment addressed the question of whether reading comprehension and speed could be predicted by eye fixations. From a sample of university students who completed tests of reading comprehension and vocabulary, we selected a group of highly skilled readers and a group of less skilled readers. These two groups then read sentences as their eye movements were monitored, with fixation locations and durations recorded. A discriminant function analysis showed that fixation duration was a successful predictor of reading comprehension, but that the number of fixations, regressive fixations, reading speed, and vocabulary were not reliable predictors. A multiple regression analysis revealed that reading speed was predicted by the number of fixations, the average fixation duration, and the duration of the final fixation upon the sentence, but there was no relationship with reading ability. Highly skilled readers are those who can extract information efficiently, but are not necessarily those who have fast overall reading rates.

Adolescent↗
PubMedDate not supplied

Individual differences in reading subprocesses: relationships between reading ability, lexical access, and eye movement control.

This study examines the relationship between individual reading subprocesses and general reading ability in college students. The reading measures included eye movements while reading a passage, lexical decision latencies, comprehension, and vocabulary size. The results indicate that a distinct relation exists between reading speed and fixation behaviour associated with regressions through a text. About half the variability in comprehension scores can be predicted by subjects' performance on nonword lexical decisions, gaze durations, and vocabulary scores. These findings are discussed with reference to past studies using similar reading measures.

Eye Movements↗
PubMedDate not supplied

Poor systemic antibody response after vaccination of commercial broiler breeders with Mycoplasma gallisepticum vaccine ts-11 not associated with susceptibility to challenge.

A live attenuated Mycoplasma gallisepticum vaccine, ts-11, has been used for control of M gallisepticum in several countries. The rapid serum agglutination test is usually used as an indicator of flock response to vaccination; however, in some flocks, the detected response may be weak or absent. We investigated whether the low level, or lack, of systemic antibodies in ts-11-vaccinated flocks is correlated with susceptibility to infection after challenge with a virulent M. gallisepticum strain. Birds from 2 separate ts-11-vaccinated commercial flocks with no, or weak, rapid serum agglutination responses (at 11 or 14 wk postvaccination) were randomly selected and subjected to aerosol challenge with either M gallisepticum strain Ap3AS or sterile mycoplasma broth. A group of nonvaccinated specific-pathogen-free chickens at similar age were also exposed to aerosolization with M. gallisepticum strain Ap3AS and used as positive controls. Postmortem examination of the birds, performed 2 wk after challenge, revealed no significant difference in microscopic tracheal lesions or mucosal thicknesses between the ts-11-vaccinated field birds irrespective of their aerosolization treatment. However, both microscopic tracheal lesions and tracheal mucosal thicknesses of nonvaccinated challenged birds were significantly greater than those of ts-11 vaccinates. Hence, broiler breeders vaccinated in the field showed significant protection against virulent M. gallisepticum challenge even when no serum antibody was detected by rapid serum agglutination test. These results reveal that seroconversion detected by rapid serum agglutination test after ts-11 vaccination is not a reliable predictor of protection against M. gallisepticum infection. The possible significance of local antibody response and cell-mediated immunity against M. gallisepticum infection is discussed.

Aerosols↗