Assumptions in cognitive
psychology
• Mental processes
• mental structures
• mental representations
Mental processes
• Series of mental processing steps when
carrying out a task
• notice that the light is red (perception)
• slow down and stop (look up in memory)
• press the brake pedal (response execution)
• your mental behavior is broken down into
processing steps
Mental structures
• E.g., short-term memory, long-term memory
• carry out processing steps using these
structures
• e.g., put information into STM (example
process)
Mental representations
• Form or shape of your understandings
• e.g., your understanding of how a university
works
• influence your behavior
• stored in your long-term memory
Research method
• Need to measure mental processes, mental
structures, and mental representations
• cognitive psychology has specific
techniques for measuring these things
• key measures are reaction time (RT),
accuracy
Reaction Time
• How long to perform a task
• measure from start -- time information first
given
• measure to the end -- time of the final
response in the task
Units of RT
• Millisecond = 1/1000 second (ms or msec)
(e.g., how long to recognize an object)
• seconds (e.g., name one professor from two
terms ago; a memory task)
• minutes (e.g., taking an exam)
Accuracy
• How well you perform a task
• usually, what percentage of a task did you
do right (e.g., 85% on an exam)
• or, proportion correct (PC) 0.85
• error rate = how poorly a task is performed
(e.g., driving errors when using cell phone)
• error rate --> a proportion or percentage
COFFEE
IS THIS A WORD?
TYPICAL SPEED = 500 MS
What does the RT tell us?
• Speed of response tells us that our words in
our head (mental dictionary) must be
organized in some very good fashion
• RT measures the organization of our mental
dictionary
Example of accuracy as measure
• Give a list of words to memorize (say about
20 words, 2 seconds per word)
• typical results: words at beginning of list
remembered well (high accuracy)
• words in the middle are remembered
horribly (low accuracy)
• words at the end are remembered well
explanation
• Beginning words benefit because there are
so few at the beginning and you have time
to work on them and get them into memory
• middle words add too much for you to
process at once, so performance declines
• last words benefit from being in short-term
memory