Speed/accuracy tradeoff
• Negative relationship between RT and
accuracy
• the faster you go (RT), the worse your
performance (accuracy)
• when you go really fast, performance at
worst
• worst performance = guessing or chance
Guessing or chance performance
• Just by chance, you get the right answer
sometimes
• on a multiple-choice test, with four
alternatives per question, one-quarter
chance of getting answer right
• e.g., with 60 m-c questions, guessing gets
you 15 correct (1/4)
Slowing down on a task
• Slower you go, the more accurate you get
• maximum = “ceiling” or asymptote (flattens
out)
Interpreting SAT
• Individuals with fast RTs, accuracy may
decline due to SAT
• individuals with slow RTs, accuracy may
increase due to SAT
Speed/Accuracy Tradeoff
Accuracy on Task (%)
120
100
80
Asymptote
60
40
20
0
really fast
fast
intermediate
Speed of Response
slow
really slow
Verbal report
• Listening to what people are saying goes on
in their heads when doing a task
• done while a person is doing a task
• verbal report = what is said (the words)
• assumption = people already, normally,
have thoughts going on while doing a task
Verbal reports (cont.)
• Called “protocol” = transcript of what a
person said out loud while doing a task
• also known as “think aloud” technique
• a “window” into mental structures,
processes, and representations
• thoughts in the protocol represent the
mental processes during the task
• Thought is the outcome or end-result of a
mental process
• e.g., reading an overhead, think-aloud might
produce “click” as your verbal report, which
represents the output of having perceived
and read the word “click”
Measuring RT
•
•
•
•
Typical device is the computer
e.g., how long to press a key
or how long to speak (vocal response)
or how long to make any physical response
(manual [hand] responses or foot responses)
Measuring RT (cont.)
• Use a stopwatch (seconds or minutes)
• compare to computer (milliseconds)
• or, give a fixed period of time and see how
far they get --> see how much is done in
that period of time (response-deadline
method)
Measuring accuracy
• Typically, done on a computer
• or keep a record, then go back and compute
accuracy
• easy approach = count number of correct
responses (paper-and-pencil)
Measuring verbal reports
• Typically use cassette recorder and
microphone to record the verbal report
• then, transcribe (to paper) and analyze the
transcripts