Week 1

Question 1

What is psychophysics?

Answer 1

A study of the quantifiable relationship between a stimulus and perception.

Question 2

The minimum stimulus magnitude at which a stimulus can be reliably detected is know as the _____?

Answer 2

absolute threshold

Question 3

Describe the procedure involved with a method of constant stimuli?

Answer 3

1. Construct a set of stimuli with a range of magnitudes.
2. Present stimuli in random order
3. Plot the results
4. Threshold is taken as the magnitude at which the stimuli is detected at a pre-determined proportion of the time. (e.g. 50%)

Question 4

Describe some ads and disads of the method of constant stimuli.

Answer 4

Ads- allows shape of psychometric function to be established, provides an accurate estimate of threshold.
DisAds- time consuming, requires pre-testing to establish threshold region, wastes trials, difficult to measure changes over time.

Question 5

Describe method of limits protocol.

Answer 5

Asc or desc, presents stimuli at sub threshold level, increase until the participant can detect. this is the threshold

Question 6

Describe some ads and disads of the method of limits

Answer 6

Doesn’t plot shape of psychometric function. Quicker. Habitual ‘yesses’ or ‘nos’ not so accurate, still wastes trials.

Question 7

Describe the adaptive staircase procedure

Answer 7

staircase run until a reversal is evident. Staircase direction changes. procedure is terminated after a criterion number of reversals.

Question 8

The mathematical formula for determining what threshold the adaptive staircase is measuring is:

Answer 8

n square root 0.5

Question 9

The two conditions in Signal Detection Theory are:

Answer 9

Catch Trials, Signal Trials

Question 10

Activity that stimulates our sensory system and results in a positive response during a catch trial is called:

Answer 10

Noise

Question 11

What does dprime measure in signal detection theory?

Answer 11

The sensitivity, the difference between the noise and signal + noise distribution. Big prime means the experiment is easy - the trial is easy to detect or reject - big distinction.

Question 12

Why might you use the double adaptive staircase method?

Answer 12

If you suspect there might be strong participant bias - prevents against anticipation

Question 13

How do you measure d prime?

Answer 13

The difference between correct rejection and hits.

Question 14

What do the receiver operating curves signify?

Answer 14

The relationship between false alarms and hits.