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Biomedical subjects

M B Lewis

Publications and source records attributed to M B Lewis.

At least 19 recordsLinked to original sources
PubMed2003

Neurologic complications of liver transplantation in adults.

OBJECTIVE: To describe the incidence and nature of neurologic complications following liver transplantation. METHODS: Adult patients who received liver transplants at St. James's University Hospital between September 1, 1990, and August 31, 2000, were identified. Case notes were reviewed and demographic data, details of the liver disease, neurologic complications, and discharge information were recorded. RESULTS: The authors identified 657 patients and traced the case notes of 627 (95.4%). These patients had a total of 711 transplants. Neurologic complications occurred following 185 transplants (26%) affecting 170 patients (27%). The most common complications were diffuse encephalopathies, which affected 66 patients (11%), and seizures, which affected 37 patients (6%). Forty-three percent of patients with alcoholic liver disease and 41% of patients with primary biliary cirrhosis experienced a neurologic complication. These proportions were higher than for other transplant indications (p < 0.001). Patients who experienced a neurologic problem spent longer in hospital (p < 0.01) and had a poorer outcome (p < 0.001). CONCLUSIONS: Neurologic complications occur following 26% of liver transplants. A higher proportion of patients who received transplants for alcoholic liver disease and primary biliary cirrhosis experienced neurologic complications than those receiving transplants for other reasons. Patients who experience a neurologic problem spend longer in hospital and have a poorer outcome.

Adult↗
PubMed2001

Re-evaluating age-of-acquisition effects: are they simply cumulative-frequency effects?

The time it takes to read or produce a word is influenced by the word's age of acquisition (AoA) and its frequency (e.g. Quarterly Journal of Experimental Psychology 12 (1973) 85). Lewis (Cognition 71 (1999) B23) suggested that a parsimonious explanation would be that it is the total number of times a word has been encountered that predicts reaction times. Such a cumulative-frequency hypothesis, however, has always been rejected because the statistical effects of AoA and frequency are additive. Here, it is demonstrated mathematically that the cumulative-frequency hypothesis actually predicts such results when applied to curvilinear learning. Further, the data from four influential studies (two of which claim support for independent effects of AoA and frequency) are re-analyzed to reveal that, in fact, they are consistent with a cumulative-frequency hypothesis. The conclusion drawn is that there is no evidence with which to refute the most parsimonious of explanations, i.e. cumulative frequency can account for both frequency and AoA effects.

Age Factors↗
PubMed2001

The lady's not for turning: rotation of the Thatcher illusion.

Inversion is especially detrimental to the processing of faces. This is clearly demonstrated by the Thatcher illusion. It has been suggested that this detriment is due to a loss of holistic or configural processing for inverted faces (Bartlett and Searcy, 1993 Cognitive Psychology 25 281-316). Stürzel and Spillmann (2000 Perception 29 937-942) suggest that this loss of configural processing occurs suddenly as a face is rotated slowly from upright to inverted. This hypothesis is tested in a study of the reaction times taken to indicate that a face has been Thatcherised at various angles of orientation. The results suggest that there is a gradual loss of configural information rather than a rapid switch from one type of processing to another.

Analysis of Variance↗
PubMed2000

The effects of massive repetition on speeded recognition of faces.

Models of face processing suggest that recognizing a person should prime recognition of a consecutive, but different, image of the same person. This prediction is tested in four experiments using large blocks of different views of the same person. The experiments demonstrate that reaction times decreased according to a negative power function as the number of repetitions increased. After sufficient repetitions, however, the reaction times lengthened. The presentation of a different familiar person between blocks of repetitions caused the reaction time for the target to increase to a level equivalent to that with no repetitions. Experiments 2 and 3 investigated the effect of different intervening stimuli (unfamiliar faces and objects). Such stimuli reduced the effect of mass repetition--but the reduction using a familiar face was greater than that with either unfamiliar faces or objects. Experiment 4 confirmed that the effects of massive repetition occur for a face familiarity task as well as for face identification tasks. The results are discussed in terms of the predictions of Burton's (1994) IACL model.

Association Learning↗
PubMed2000

Telesales neuropathy.

A case of bilateral ulnar neuropathies caused by overuse of the telephone is described in a 17 year old double glazing salesman. The importance of taking a good occupational history is emphasised and the need for correct staff training and appropriate equipment highlighted.

Adolescent↗
PubMed2000

Satiation in name and face recognition.

Massive repetition of a word can lead to a loss of meaning (i.e., semantic satiation). Satiation is a general property of neurons and so it would be expected that semantic satiation would be found for stimuli other than words. Three experiments examined the occurrence of satiation for the repetition of names, the visualization of faces, and the repetition of faces. Reaction times to a decision based on a repeated name or face were longer following 30 repetitions than following 3 repetitions, indicating that satiation had occurred. Mere visualization over the same time interval, however, did not elicit satiation effects.

Cognition↗
PubMed2000

Mistaken first impressions: a response.

In this journal, Cummins et al reported an experiment that examined clinicians' predictions of causes of death from subjects' pre-morbid photographs. They found that clinicians performed at chance. The validity of two of their other conclusions are challenged. First, that clinicians routinely form impressions of how a person will die from their appearance. Second, that certain health professionals use common judgements to form these impressions. These claims are found to be based upon non-falsifiable hypothesis and inappropriate statistics; hence, an experiment employing pictures of feet (or any arbitrary personal detail) would have led the authors to the same conclusions.

Cause of Death↗
PubMed1999

Age of acquisition in face categorisation: is there an instance-based account?

An instance-based model of the effects of age of acquisition (AoA) is offered and derived predictions are considered. A face-categorisation experiment is reported which tested these predictions. Nine participants made speeded-categorisation judgements of 185 faces from two TV shows. Ratings were given for the faces' frequency of occurrence in the shows and, for each face, the length of time the character was in the show and the time since they had left was found. Regression analyses were used to find how the factors affected the speed of categorisation. Speed of categorisation was found to follow a negative power function of the frequency and time on the show and a positive power function of the time since they had left. This was supportive of the instance-based account and suggests that effects of AoA with words and objects can be explained in terms of cumulative frequency.

Adult↗
PubMed1998

Understanding caricatures of faces.

Lateral caricatures are transformed faces like caricatures but the transformation is orthogonal (in the face-space, Valentine, 1991) to the direction of caricaturization. It has been reported that lateral caricatures are more difficult to recognize than anti-caricatures (Rhodes & Tremewan, 1994). To investigate this effect, oblique caricatures (transformed obliquely to caricaturing) were generated by morphing between a veridical face and a reference face. Two experiments used a forced-choice similarity task to find which images are perceived to have the least change from the veridical. An advantage for caricatures over anti-caricatures was found, but none was found between oblique and anti-caricatures. Performance of theoretical lateral caricatures was extrapolated from the oblique caricature data. These lateral caricatures would be perceived as more similar to veridical faces than were the anti-caricatures.

Adult↗