Problem 6 Flashcards
Cognitive subtraction
Compares the activity of the brain in a task that utilizes a particular cognitive component to the activity of the brain in a baseline task that does not use this
–> one can thus infer which regions are specialized for this particular cognitive component
How did petersen figure out which regions are involved in spoken words ?
By comparing the passive viewing of written words with reading aloud the word
–> both experimental and baseline tasks involve visual processing the word but only experimental involves spoken output
How did peterson figure out which regions are involve with retrieving the meaning of written words ?
By comparing a verb-generation task (see cake but say eat) with reading aloud (see cake say cake)
–> both experimental + baseline tasks involve visual processing, word recognition + spoken output but only experimental involves understanding the meaning
How did petersen figure out which regions are involved with recognizing words ?
By comparing brain activity when passive viewing the word cake with passively viewing a cross
–> both experimental + baseline tasks involve visual processing but only experimental involve visual word recognition
Assumption of pure insertion
Assumes that adding a different component to a task does not change the operation of other components
–> disadvantage of cognitive subtraction
e.g.: it could be that th amount of visual processing that ideal with written words is not the sam as for non-linguistic vision
Interaction
Refers to the effect that one variable has on another
–> thus the addition of an extra component in the task may potentially change the operation of other components in the task
Why are baselines so important to functional imaging ?
Because without it the regions of activity can not be meaningfully interpreted.
–> thus a good cognitive theory of the elects that comprise task must be established so an appropriate baseline can be selected
Efference copy
Refers to a motor signal that is used to predict the sensory consequences of an action
–> explains why we can’t tickle ourselves because we know what this would mean
Categorical design
Measures differences in brain activity between 2 or more conditions
Functional specialization
Implies that a region responds to a limited range of stimuli/conditions and that this distinguishes it from the responsiveness of other neighboring regions.
Functional integration
Refers to the way in which different regions communicate with each other
Block design
Presenting stimuli sequentially within a condition and then alternating the grouped conditions (based on similar stimuli)
–> AB block design in which a cycle corresponds to two epochs
Event related design
Linking the BOLD response to specific events, such as the presentation of a stimulus or the onset of a movement
–> a clear signal can be obtained by averaging over repetitions of these events
THUS: allows the researcher to present experimental and control trials randomly, ensuring that participants are in a similar attentional state during both types of trials
What is the advantage of block designs over event-related ones?
More power
–> more able to detect significant but small effects
What are the advantages of event related designs over blocked ones ?
- Enable a much wider range of experimental designs
2. Are more closely related to the typical design structure of most cognitive psychology experiments
