Problem 1

Question 1

Cognitive neuroscience

Answer 1

Study of mental activity as an information-processing problem

–> seeks to identify internal processing of info that underlies observable behavior

Question 2

Letter matching task

Posner

Answer 2

1. 2 letters are presented simultaneously in each trial
2. Evaluate whether they are both consonants, both vowels or a mix
   (3. Adding of 2 other conditions where 2 letters are the same (physical) or same letter but one capital other lowercase (phonetic))

Question 3

Result of posners experiment

Answer 3

We derive multiple representations of stimuli that are based on

1. the physical aspects
   - -> AA
2. on the letters identity
   - -> Aa
3. categorization
   - -> vowel or consonant

THUS: different response latencies reflect the degrees of processing required to perform this taks

Question 4

Dependent variable 
(letter-matching task)

Answer 4

Reaction time

–> the speed with which the participants make their judgments

Question 5

Participants must engage in 4 primary operations for sternbergs task.

Name them

Answer 5

1. Encoding
2. Comparing
3. Deciding
4. Responding

Question 6

Donders subtraction method

Answer 6

1. Construct 2 tasks that differ only in a single component of processing
2. Measure RT in both tasks
3. Substract the RTs
4. Outcome is the duration of that single component
   e. g. like letter matching task

Question 7

Reaction time 
(Operational definition)

Answer 7

Refers to the time interval between the onset of a stimulus and the overt response to that stimulus

–> here button press
BUT: assumes that the participant intends to be as fast as possible w/o making errors

Question 8

2-choice RT

B type Donders task

Answer 8

2 possible stimuli and each of them demand a different response

–> reaction times are longer here than A

Question 9

Go-nogo Task

C type Donders task

Answer 9

2 possible stimuli and one possible response

–> repsonding to go but not logo

Question 10

Assumptions of Donder’s method

Answer 10

1. Seriality
   - -> processing stages are carried out in a strictly serial manner
2. Pure insertion
   - -> when an extra stage is added/removed the duration of all other processing stages remain the same
3. Presupposes detailed knowledge about the processes invoved

Question 11

Why was the assumption of pure insertion criticized ?

Answer 11

Appears to be open to empirical verification

–> although it may be possible to construct tasks in which this is valid, in many, like the donders original one it is likely not

Question 12

Sternbergs memory search task

Serial processing

Answer 12

1. Set of 1-6 letters is presented, to memorize
2. One letter is then demonstrated after the rest disappeared
3. Participant has to decide whether that letter was in the initial set
4. Indicate yes or no

–> Comparing sensory info (stimulus) with representations that are active in memory

e.g.: How fast can we search memory?

Question 13

Factor

Answer 13

Independent variable in an experiment

e.g. gender

Question 14

Levels

Answer 14

Set of values of a factor

e.g. gender = male + female

Question 15

Main effect

Answer 15

Is the Mean of all the simple effects of a factor

Question 16

Simple effect

Answer 16

Is an effect of one factor at one particular level of a factor

Question 17

Interaction

Answer 17

If 2 manipulations modify each others affect, they will also affect a stage in common

Question 18

Additive effects

Answer 18

If 2 manipulations affect different stages, then the effect of one will not depend on the other

Question 19

Main assumptions of AFM

Answer 19

1. Seriality
   - -> thus total RT is simply the sum of the stage durations
2. If we use some experimental manipulation to increase RT, then the durations of one or more processing stages is increased
   - -> BUT output of the stage is not changed in quality (constant + independency of stages)
3. Later stages of processing cannot compensate for any delays earlier on
   - -> increased duration of some stage is simply propagated through all following stages

BUT: Does NOT assume pure insertion

Question 20

Stage robustness

Answer 20

Obtained if the pattern of additivity or interaction among factors does not change if the factors are combined with a new factor

Question 21

Speed accuracy tradeoff

Answer 21

There is a tradeoff in how fast a task can be performed vs how many mistakes the participant makes

–> because the faster a participant responds, the more errors they make

Question 22

Diffusion model

Answer 22

Provides a theory that explains the distribution of RTs of both correct and error responses in a 2-choice RT task

• ->
  1. as info accumulates between stimulus onset and the response

2. represented by an internal counter, reacting to the received information supporting different outcomes (correct vs. incorrect) by shifting in opposite directions
3. when the counter hits the lower or higher threshold a certain response (a or b) is elicited
4. random noise alters the counter
   - -> explains the variation of RTs in each trial, while the stimulus remains the same

Question 23

Word superiority effect

Answer 23

One is most accurate in identifying target letters when they are part of a word

–> we do not need to identify all the letters of a word before recognizing the word

Question 24

Reaction time
(Theoretical definition)

Answer 24

Refers to the minimum amount of time needed by the participant to produce a correct response

Question 25

Advantages of RT

Answer 25

1. Mental processes have no physical properties but time can be measured
2. Highly sensitive to subtle differences btw conditions
3. It is the actual variabel of interest

Question 26

Disadvantages of RT

Answer 26

1. Reflects only the end product of cognitive processing whereas the actual functions are hidden
2. Cant use it for more complex tasks

Question 27

Sternbergs additive factors method

AFM

Answer 27

Discovers independent stages, thus how many there are and what they do

–> assumes that in a sequence of stages (=mental modules) eachh does some operations and hands output to the next

Question 28

How may one correct the speed accuracy trade-off ?

Answer 28

Since there is no evidence that the participants actually use the minim possible amount of time to react:

–> Running the same task multiple times and give a different speed accrue instruction every time

Question 29

How accurately can one identify outliers in RT measurements ?

Answer 29

This is difficult since one cannot discriminate between “true” slow RTs and outliers

–> should thus stress the importance of

1. consistency
2. practice
3. brief tasks
4. feedback

to keep people alert

Question 30

Assumptions of the diffusion models

Answer 30

1. Info accumulates continuously during the time between stimulus onset + response
2. Info is represented by an internal counter which is driven in opposite directions by tiny bits of info supporting the different outcomes (correct vs incorrect)
3. There is random noise in this info that drives the counter

–> explains the variation in the outcomes even when the stimulus is the same

Question 31

Random walk

Answer 31

Simulating the random noises the drive the internal counter with a computer program

–> to obtain simulated RT distributions, that mimic actual ones as closely as possible

Question 32

How do you investigate SAT?

Answer 32

1. Sample the whole SAT function in each condition, by repeating the experiment many times under different speed-emphasis instructions (takes a lot of time and effort).
2. Fit both RT and accuracy by a single mathematical model
   - -> If the model’s assumptions are fulfilled, the best fitting parameter values of the model accurately describe the characteristics of the underlying processing

THUS: diffusion models: IMPORTANT