Treisman (1960) Used shadowing task Listen to one ear: I saw the girl / song was wishing (correct answer) Ignore other ear: me that bird / jumping in the street Results: people can’t help but switch over to other message that they are ignoring

Interpretation of results Support late selection  people were processing the meaning of the ignored message

Recent selection model Pashler (1998) (p. 65) Both early and late selection occur Early selection is done in a bottleneck-like fashion (some material is completely shut out) Late selection done through capacity sharing  split capacity to process multiple messages

Generality of selective attention concepts Shadowing experiments involve auditory information But, similar concepts and theories for visual information, as well

Information Processing Model STM SENSATION PERCEPTION ATTENTION SENSORY STORE (e.g, ICON)

Short-term Memory Aka, the short-term store (old-fashioned) Aka, working memory (temporary storage of information to do a task) Aka, short-term working memory Aka, primary memory (James)

Try these math problems 4 X 9 = _____? Answer: 36 (remember directly, don’t have to figure out) 35 X 8 = ______? Answer: 280 (you computed this in your head) 261 X 97 = ______? Answer: 25,317 (very very difficult to do in your head) Problem -> information gets jumbled in your head

Interpretation There is a limit on how much information we can keep track of in our heads at a time (aka, a “capacity limit”) Capacity limit is related to your short-term memory (in other words, your short-term has a limited capacity for holding information)

How much does STM hold? Use digit span task Hear a list of random digits (single digits) Repeat back in order E.g., Gradually increase the length of the list Keep going until you make mistakes Commonly between 4 and 10 digits

interpretation Your digit “span” = number of digits that you can repeat back without mistakes Conclusion – can hold only a little bit of information in short-term memory at a time

Capacity of STM Are multiple methods for measuring capacity of STM But estimates are always comparable Miller analyzed numerous tasks to estimate STM capacity  7 +/- 2 Can hold 7 +/- 2 items in STM “chunk”  the item in STM can be an individual item or can be a meaningful “chunk” of items

In digit span task, use individual digits (e.g., 1) Alternatively could use letters, (now called letter span task)  spans in same range as digits Alternatively, could use words (e.g., milk eggs celery chicken etc.) (now called word span task)  same results

But, one word is composed of several letters, so 7 +/- 2 words is many more letters than 7 +/- 2 letters What you are remembering is chunks—not individual letters Chunk = meaningful unit

3 things to know about a memory structure Capacity = how much it can hold Duration = how long information is held –Sensory memory  less than 1 second –STM  up to 30 seconds Code (or Format) = the way in which information is held in memory

Different codes Reflect how your mind stores information in memory (similar to computer using 1’s and 0’s) General possibilities: –Acoustic code – information stored in terms of how it sounds –Visual code – in terms of looks –Other codes tied to senses: olfactory (smell), tactile (touch), gustatory (taste)

More on codes Semantic code = refers to the meanings of things E.g., letter span task, hear the letter “C” Acoustic code for “C” = “see” Visual code for “C” = “C” (what it looks like) Semantic code for “C” = 3 rd letter of alphabet; average grade