Category Archives: Breathlessnes

Canadian Health and Care Mall: Frequency Method of Breathlessness

behavioral psychologyThe object of the study is to define the minimum increase (or decrease) in tidal volume reliably detected by a subject. The subject produces a constant tidal volume (one method would be by targeting to a volume trace on an oscilloscope). A number of test stimuli are then administered. The test stimuli consist of the reference volume and the volumers bridging the detection threshold. Following the presentation of a reference tidal volume, the subject targets to a slightly bigger (or smaller) volume by altering the gain on the scope unknown to the subject—the visual target is the same. The subject is then asked to make a forced choice: Is the volume the same? (“yes” or “no”). After many trials the positive responses, expressed as a percentage of the total number of presentations for each tidal volume, are plotted against the tidal volume. The detection threshold is defined as the volume detected bn 50 percent of presentations, and the percentage of positive responses for the reference volume is taken as an index of response bias. The threshold volume is conventionally expressed as a fraction of the background volume to define the Weber fraction.