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