February 26, 2001 page 1 S. Derenzo
Solutions for Midterm #1 - EECS 145M Spring 2001
1a
• Acquire a computer with a digital I/O port and an internal clock
• Connect a pushbutton switch to one line of the digital input port and one line of the output port
to an amplifier and fast light (like an LED)
• Write a computer program that detects a pushbutton, waits a random delay, prompts the
subject by turning on the light and measures the time until the pushbutton is pressed
• Select a large number of candidates representing group d (racecar drivers) and group p (jet
fighter pilots)
• After initial training and a good nights sleep, take as much reaction time data as possible,
allowing for rest periods
• Compute the average reaction times dp and , the standard deviation of the samples
σσ
dp
and , and the standard errors of the mean σσ
dp
and and compute Student’s t:
tdp dp
mm
dpdd pp
== −
+=−
+
∆
∆
σσσ σ σ
22 2 2
//
• Look up the probability of exceeding this value or t by chance. If the probability is < 0.1%,
then the group with the lowest average has a faster reaction time.
[2 points off if only two subjects]
[1 point off if probability mentioned but not looked up or calculated]
2a
remote
µcomputer
camera and
interface
input port
output port
central
µcomputer
input port
output port
data
data available
ready for data
2b
1 car passes, remote computer acquires license plate number
2 remote computer stores license plate in local memory
3 remote computer waits until central computer signals “ready for data” TRUE (meanwhile steps
1 and 2 can continue and new license plate numbers can stack up in local memory)
4 remote computer writes license plate number to its output port and signals “data available”
TRUE
5 central computer reads data, sets “ready for data” FALSE
6 remote computer sets “data available” FALSE
[4 points off for setting “data available” TRUE before the data have been asserted
