Semantic Memory Knowledge memory Main questions How do we gain knowledge? How is our knowledge represented and organised in the mind-brain? What happens when we access information? (Note 2 nd and 3 rd questions are strongly related.)

Semantic Memory Knowledge memory Main questions How do we gain knowledge? How is our knowledge represented and organised in the mind-brain? What happens when we access information? Test predictions of semantic network model

Semantic Memory Important task lexical decision task make a word-nonword judgement for a letter string

murget

higgle

beer

stout

Semantic Memory Important task lexical decision task make a word-nonword judgement for a letter string Priming paradigm examine the influence of one stimulus on the production of (e.g., naming of) or lexical decision for another stimulus

Animal Breathes Skin Fish Gills Tail fin Trout Swims Eel Perch Gills

Spread of activation means that some nodes will be more highly activated following the activation of a related concept Decisions for or naming of some concept (node) should be facilitated by the activation of a related concept Example: Activation of “fish” should facilitate (speed up) the lexical decision RT for “salmon” compared to an unrelated concept (e.g., chair – salmon)

Test some predictions of the semantic network Use of word naming as a task (name/read a word as quickly possible)

Fruit

P

Loftus & Loftus (1974) presented fruit – P (subject gives a name of fruit starting with P) investigated idea that priming dissipates with time immediate vs. delayed repetition of category Reasoning: 1 trial could prime performance on a later trial (priming across or between trials) If activation decreases with time, then there should be more priming on an immediate trial compared to a delayed trial

Loftus & Loftus (1974) PrimeTarget Trial 1 fruit A(initial trial) Trial 2 fruit P (immediate, lag = 0) PrimeTarget Trial 1 fruit A(initial trial) Trial 2 vehicle T Trial 3 fish S Trial 4 fruit P (delayed, lag = 2) Prediction: Naming RT should be lower (faster) for the immediate trial compared to the delayed trial.

Naming RT as a Function of Condition Condition 1400 RT (ms) initial trial lag = 0 lag = 2 Category Repeat 2300

Naming RT as a Function of Condition Condition 1400 RT (ms) initial trial lag = 0 lag = 2 Category Repeat st trial primed later trials

Naming RT as a Function of Condition Condition 1400 RT (ms) initial trial lag = 0 lag = 2 Category Repeat 2300 more priming for lag=0 than lag=2

Loftus & Loftus (1974) PrimeTarget Trial 1 fruit A(initial trial) Trial 2 fruit P (immediate, lag = 0) PrimeTarget Trial 1 fruit A(initial trial) Trial 2 vehicle T Trial 3 fish S Trial 4 fruit P (delayed, lag = 2) Prediction: Naming RT should be lower (faster) for the immediate trial compared to the delayed trial. Prediction upheld. Conclusion: Activation decreases with time.

Other examples

nurse

doctor

nurse (prime)

doctor (target, right after prime) (make a lexical decision for “doctor” or pronounce “doctor”)

Does “nurse” prime “doctor”? Compare RT for nurse – doctor (related condition) shoe – doctor (unrelated condition) nurse – doctor RT < shoe – doctor RT xxx – doctor RT (neutral) blank – doctor RT (neutral) Difference is a priming score.

Basic semantic priming effect: Presentation of nurse speeds up (facilitates) lexical decision or proununciation time of doctor compared to a control condition

Basic semantic priming effect: Is spread of activation automatic? Evidence mediated priming effects at short SOAs effects at short SOAs despite exectancy

Basic semantic priming effect: Is spread of activation automatic? Evidence Mediated priming (Lorch & Balota, 1986) nurse related to doctor, doctor related to lawyer nurse not related to lawyer nurse – prime lawyer – target nurse facilitates pronunciation time for lawyer! Priming is mediated by doctor! i.e., activation spreads from nurse to doctor to lawyer

Basic semantic priming effect: Is spread of activation automatic? Choosing the right control condition Evidence effects at short SOAs effects at short SOAs despite exectancy

Control condition: shoe (prime) - doctor (target) What if shoe affects decision RT for doctor?! That is, maybe shoe – doctor is not a good control condition. Need a better control condition: xxx (not a word) Does nurse affect decision RT for doctor? Does shoe affect decision RT for doctor?

What if shoe affects decision RT for doctor? Need a control condition: xxx Does nurse affect decision RT for doctor? Does shoe affect decision RT for doctor? Compare RT for nurse – doctor (related condition) xxx – doctor (control or neutral condition) shoe – doctor (unrelated condition)

Compare RT for nurse – doctor (related condition) xxx – doctor (control or neutral condition) shoe – doctor (unrelated condition) nurse – doctor RT < xxx – doctor RT Facilitation

Compare RT for nurse – doctor (related condition) xxx – doctor (control or neutral condition) shoe – doctor (unrelated condition) shoe – doctor RT > xxx – doctor RT Inhibition

Neely (1976) related, unrelated, and neutral primes also manipulated prime-target SOA basic idea: shorter SOA—decision based on automatic processes longer SOA—decision based on automatic + controlled processes

see Overhead Figure 6.10 from Ashcraft (1998)

RT (in ms) as a function of prime-target condition and SOA Prime-Target ConditionSOART Neutral Related (17 ms facilitation) Unlrelated (19 ms inhibition) Neutral Related (45 ms facilitation) Unlrelated (10 ms inhibition) Neutral Related (52 ms facilitation) Unlrelated (19 ms inhibition)

RT (in ms) as a function of prime-target condition and SOA Prime-Target ConditionSOART Neutral Related (17 ms facilitation) Unlrelated (19 ms inhibition) Neutral Related (45 ms facilitation) Unlrelated (10 ms inhibition) Neutral Related (52 ms facilitation) Unlrelated (19 ms inhibition)

Neely (1976) Results show facilitation and inhibition Results show an increase in facilitation from SOA of about 350 to an SOA of 600 Why should facilitation increase? Two types of processes at work? Maybe initial facilitation is automatic. Maybe extra facilitation is due to controlled processes.

Neely (1977) related, unrelated, and neutral primes also manipulated SOA AND expectancy (thought to reflect controlled processing, which should take some time to be able to be used)

Neely (1977) Expectancy (thought to reflect controlled processing, which should take some time to be used effectively) see bird prime, expect a type of bird as a target

bird

robin

bird

dove

bird

arm

Neely (1977) Expectancy (thought to reflect controlled processing, which should take some time) see bird prime, expect a type of bird as a target sometimes get a type of bird as a target on occasion, get a word from a different category as a target

see Overhead Figure 6.11 (left panel) from Ashcraft (1998)

Only facilitation at first (short SOA), no inhibition facilitation effect based on automatic processing (the expectancy hasn’t had time to kick in) As SOA increases, faciliation and inhibition increase increases based on controlled processing (the expectancy has now kicked in and is being used)

Neely (1977) Expectancy (see Table 6.2 from Ashcraft, 1998) (thought to reflect controlled processing, which should take some time) see body prime, expect part of a building as a target (i.e., expect a category shift)

body

window

body

roof

body

door

body

heart

Neely (1977) Expectancy (see Table 6.2 from Ashcraft, 1998) (thought to reflect controlled processing, which should take some time) see body prime, expect part of a building as a target (i.e., expect a category shift) sometimes get part of a building as a target (expected, but not actually related to the prime) on occasion, get a body part as a target (actually related to the prime, but not expected)

see Overhead Figure 6.11 (right panel) in Ashcraft (1998)

Expected Shift, but Unrelated prime-target (e.g. body – door) No facilitation at first (short SOA), But facilitation at longer SOAs No effect based on automatic processing Later facilitation based on controlled processing (the expectancy)

Related prime-target, but not expected (e.g., body – heart) Facilitation for short SOA (even though not expected) Inhibition for later trials (even though related) Initial facilitation effect based on automatic processing (*occurs despite expecting an unrelated target) Later inhibition effect on controlled processing (the expectancy)

Facilitation in 250-ms SOA condition for related, but unexpected target provides strong evidence for the idea priming is automatic—consistent with the idea of spread of activation. Evidence from longer SOAs Controlled processes can contribute quite a bit to inhibition and facilitation effects.

Semantic Memory Main questions How do we gain knowledge? How is our knowledge represented and organised in the mind-brain? What happens when we access information? 1)Good evidence for automatic activation of related information (spread of activation). 2) Activation drops fairly quickly. 3) Controlled processes affect performance and need to be dealt with in terms of theory.