01:830:301 Lecture Notes - Lecture 4: Dendrite, Action Potential, Psychometric Function
Document Summary
Have fixed set of stimuli but don"t show them in random order. We show them as up sequences or down sequences (systematic order in terms. Lecture 4 of increasing or decreasing intensities): start with weak (undetectable) stimulus, gradually increase intensity, mark crossover point . Stop where they say no (n) first time or yes (y) the first time and determine crossover point: yyyyyynyyy or nnnnnynnn. There is no way to know if they are redoing the task. Set up task so that there"s always a right answer. Example: dim light flashes either on left or right of screen. Psychometric function looks same as 1st method except for two differences, which. If invisible, observer has to guess -> on average, approx 50% correct. 100% is guessing (50%), perfect score (100%) and y-axis is percent correct. Doctrine of specific nerve energies (j. muller) What matters is which nerves are stimulated not how they"re stimulated : lesion studies (neuropsychology)
