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Abstract

An investigation into the relative efficiency of Threshold
and Signal Detectability measures of olfactory Sensitivity was undertaken
using isopropyl alcohol as stimulus. Intensive testing of seven
subjects under adaptive and non-adaptive conditions revealed that the
Signal Detectability paradigm, although theoretically desirable because
of its allowance for the subject's response bias, was difficult to
implement because of the prolonged testing required. A variance of the
rating technique involving multiple stimulus concentration presentations
in a three-hour testing session was attempted. Results in the nonadapting
environment indicated that the method was more effective than
single-stimulus concentration presentations. However reliable results
under adapting conditions were obtained In the case of one subject only.
As a comparison, the constant stimulus method was used to
obtain threshold using a procedure similar to Cheesman's and Mayne's
group threshold determinations, but modified for individual subject
testing. Practice and learning effects were noted and their relevance
discussed. The Cheesman hypothesis viz, that adapting odour concentration
and threshold elevation obey a linear logarithmic relation which
is characteristic of the adapting and test stimulus compounds was
confirmed in two subjects only. Reasons for non-confirmation include
the extended adapting stimulus concentration range, subject boredom
and inadequate control of the stimulus; the latter factors being a
consequence of prolonged testing.
The sniff-bottle and air-dilution forms of stimulus presentation
were employed, although not with the same subjects. Thus a
direct contrast of these presentation methods was not possible.
However results were generally more consistent with the air-dilution
technique.
The feasibility of an odour classification based on subject
responses during adaptation rather than on molecular parameters was
evaluated and the difficulties likely to be encountered in employing
Signal Detectability measures of sensitivity was discussed.

Item Type:	Thesis - Unspecified
Authors/Creators:	Fraser, John W.(John William)
Keywords:	Olfactometry, Smell
Copyright Holders:	The Author
Copyright Information:	Copyright 1974 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).
Additional Information:	Thesis (M.Sc.)--University of Tasmania, 1975. Includes bibliographical references
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