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following a suggestion that most recordings with validated shifts had been<br />
removed from the series, while in fact only normal echograms were<br />
withdrawn. No such studies are known about physical signs.<br />
The possible role of prejudice in the clinical interpretation of plantar<br />
reflexes was included in this study because its presence would require more<br />
objective methods. Thus the question was whether the idea that a Babinski<br />
sign ought to be there or not, on the strength of information about other<br />
signs and symptoms, biased the answer 'up' or 'down'.<br />
Subjects<br />
METHODS<br />
Thirty neurologists from a Dutch university hospital rated a number of<br />
plantar reflexes on film, without being given any additional facts ('no<br />
information' group). Most of them had a few years experience in clinical<br />
neurology, some more, others less. The variability of interpretation was<br />
studied in this group, and these subjects also served as a control group for<br />
the neurologists who saw the films after some information about other<br />
signs and symptoms.<br />
The 'information' group consisted of twenty other neurologists from<br />
two other university hospitals. For practical reasons they were examined in<br />
three sub-groups, but the instructions remained identicaL It was explained<br />
that this was a study about the interpretation of plantar reflexes and that<br />
some of these reflexes were to be shown on film, accompanied by some<br />
other data in order to approach the clinical situation as well as possible.<br />
Films<br />
Nineteen short films, each showing a right foot from the medial side,<br />
formed the basis of the stimulus materiaL The films were separated by<br />
title-numbers. Except for one subgroup (six subjects) from the 'information'<br />
group, the films were shown on television. Plantar stimulation could<br />
be seen and was performed three times for every foot. Within the sequence<br />
of 19 films, two films were repeated: nr, 4 was identical with nr. 15 (film<br />
A), nr. 7 with nr. 18 (film B). These two duplicated films were the actual<br />
object of study ('test films'). All three 'reflexes' in either test film were<br />
simulated equivocal responses: slight up-and-down movements of the<br />
great toe. The other 15 films only served to cover up the two repetitions<br />
('cover films') and consisted of downward, upward, equivocal and absent<br />
hallux movements in about equal proportions (true or simulated reflexes).<br />
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