Midterm Flashcards
what is cognitive neuroscience
study of psychological processes and how they’re implanted in the brain
3 keys to conducting an fMRI study
- Design a behavioral task that isolates the psychological processes of interest in the brain
- Modify the behavioral task so that it’s suitable for an fMRI study
- Analyze the behavioral and fMRI data
ethical considerations of studies
informed consent
debriefing (tell purpose of study at the end)
privacy/confidentiality
fraud (making up data)
Four goals of scientific research
Describe: observe a behavior, make a prediction
Predict
Determine causes
Explain mechanisms
3 types of studies
descriptive: observational, notice patterns in the world and report them
correlative: notice a pattern a between two different variables and try to determine how they’re related
true experiments: random assignment, manipulate a variable
within vs between subject design
between: groups receive different treatments
within: each subject receives all treatments (makes it harder for 3rd variable to affect results
within subjects design limitation
carry over effects: effects from one experimental condition carry over to the next
timing/order of treatments matter
example of confounds
clever hans: cues from experimenters affected horse’s reaction
bigfoot
congruency effect
reaction times are faster when the target and distractor are congruent than when they are incongruent
Congruency sequence effect
(aka conflict adaptation)
the congruency effect is smaller when the previous trial is incongruent than when congruent
Which process drives the CSE?
- Selection for action (botvinick)
- shift attention toward the relevant target
- Response inhibition (ridderinkhof)
- inhibit the response engendered by the distractor
- Learning and memory confounds (mayr)
botvinick et al.
selection for action (previous theory): ACC focuses attention on stimuli we want to act upon
conflict monitoring (botvinick): ACC activated when conflict is detected, dorsolateral prefrontal cortex (DLPFC) activated, then attention is increased
Mayr et al.
- Mayr et al predicted:
- CSE happens when target and flanker are repeated
- No CSE when either target or flanker change
- Found that conflict adaptation occurred only in repetition trials, contradicting the conflict monitoring model
- CSE comes back when stimulus is repeated in n-2 to n
- Reduced ACC activity on iI (vs cI) trials reflects repetition priming not conflict monitoring
selection for action (attention adaptation) triggered by:
perceptual expectation (expectations about what comes next)
conflict monitoring
negative affect (almost pressing wrong button makes you frustrated)
cI vs iI trials in botvinick et al.
cI trials: higher conflict
iI: high selection for action
cI trials had greated ACC response
learning and memory processes that may influence the CSE include:
feature repetitions (mayr et al.)
contingency learning biases (schmidt)
Mayr et al used what kind of task
2-AFC flanker task
to avoid feature repetitions, some researchers have…
employed tasks w/ larger stimulus sets (ex: ullsperger et al.)
contingency learning confounds/biases
Ullsperger: 9-AFC (alternative forced choice)
with larger stimulus sets (to avoid feature repetitions), congruent and incongruent trials are presented equally, even though there are fewer unique congruent stimuli (shown 8x often)
flankers (ex 11 11) appeared w/ congruent target (ex 1) 50% of the time but w/ incongruent targets (22 22, etc.) only 6.25% of the time
lead to CSE
describe both experiments in mayr et al.
experiment 1: standard flanker task, but analyzed trials by whether they were a change or repetition
experiment 2: removed repetition by alternating b/w up/down and left/right arrows
what does AFC stand for
what do classic experiments use
mayr et al
ullsperger
alternative forced choice
classic: 2-AFC (left/right)
mayr: 4-AFC (right/left/up/down)
ullsperger: 9-AFC (9 possible responses)
how does a contingency learning bias lead to a CSE
particpants want to respond fast/accurately, so learn strategy of making response congruent w/ flankers
after congruent trial (strategy worked!), contingency bias increases (faster RT cC trials, slower to cI)
mental rotation confounds
Kunde and Wuhr
observed a CSE in a 4-AFC, even in trials w/o exact feature repetition or contigency learning biases)
however, all arrow stimuli were mental rotations of the same arrow stimulus
Prime probe word task (Schmidt and Weissman)
avoided feature repetitions, contigency learning, and mental rotation confounds
- 4-AFC task (left-right vs up-down)
- Alternated b/w these two tasks every trial (no response repetitions)
- Presented congruent/incongruent stimuli equally (no contigency learning)
conclusion of schmidt and weissman
CSE can be observed independent of confounds
a control process influences the CSE, but does not reveal which one:
selection for action (aka attention adapation) or response inhibition
how does prime probe word task of in class experiment differ from schmidt and weissman?
increase time separating the prime (distractor) from the probe (target) from 33 ms to 800 ms
logic of class experiment (increasing time b/w distractor and target)
overall congruency effect should vanish
however, subjects may still use their memory of what the previous trial was to predict what the next trial will be
therefore, should observe a CSE even though there is no overall congruency effect
class experiment: selection for action (attention adaptation) theory
after an incongruent trial and w/ long time b/w distractor and target, subjects can shift all attention to the target when it appears
if they shift all their attention to the target, there won’t be any attention left to identify the distractor
thus, there should be no congruency effect after incongruent trials
class experiment: response inhibition theory
w/ a long time b/w target and distractor, subject inhibit response signaled by the distractor after incongruent trials
if they do, there should be a negative (reverse) congruency effect after incongruent trials (faster on iI than iC)
CSE graph label
p value
probability that null hypothesis is false
null hypothesis = no significant difference b/w two groups
one tailed t test
test if sample mean is larger or smaller than population mean
significant when the difference b/w means are large enough that it’s unlikely to occur by chance
5% in one tail
two tailed t test
test if sample mean is larger or smaller than population mean
2.5% in each tail instead
paired (one-sample) t-test
two sample means come from the same subjects
compare subjects to themselves
unpaired (two-sample) t-test
the two sample means come from different subjects
main effect
dependent variable changes based on the independent variable
interaction
the effect of one independent variable on the dependent variable varies based on another independent variable
unparallel lines