# psychophysics anthropometrics and ergonomics

Do the “Classic” visual/motor ruler reaction time measurement study, as follows:

1. Using a rule, hold it near the end (highest number) and let it hang down
2. Have a participant put their hand at the bottom of the ruler and have them ready to grab the ruler (they should not be touching the ruler)
3. Tell the participant that you will drop the ruler sometime within the next 5 seconds and they are to catch the ruler as fast as they can after it is dropped
4. Record the level (inches or centimeters) at which they catch the ruler

Repeat multiple times (we recommend 20 times) varying the time the ruler drop within the 5 second window.

Then repeat with a different participant.

Use either the formulas or chart (to right) to convert measures to response times:

d = Â½ g t2 or

Where:

t = time (in seconds)

d = distance (in cm)

g = gravity of 980 cm/sec2 or 385.8 in/sec2

Write up your design, procedures, materials, findings and conclusions (use the scientific paper format – module 2G). Include the following:

• A simple block diagram model (no more than about 6 blocks) of the visual-motor processes involved, include both sensory and cognitive processing aspects
• Hypothesis and null hypothesis
• Independent, dependent and confounding variables
• Descriptive analysis: mean, median, mode, range and scatter plot