We would like to know whether pre-stimulus gamma oscillations can predict decision bias in a perceptual decision making task.
Source
Brief title
Condition
- Other condition
Synonym
Health condition
geen
Research involving
Sponsors and support
Intervention
No registrations found.
Outcome measures
Primary outcome
The amplitude of pre-stimulus gamma oscillations for the four different
decision bias conditions.
Secondary outcome
Fitted decision bias parameters of the drift diffusion model of decision making
(Ratcliff, 1978). This model will be fit on the basis of participant's reaction
time and accuracies.
Background summary
There is increasing evidence that neural activity even before a decision can
(to some extent) predict what the decision will be. In popular words: your
brain knows your decision before you do. We can manipulate such a decision bias
experimentally. For example, in a previous study (van Vugt et al, 2011) we
asked participants to make repeated decisions about the direction of motion of
a field of randomly moving dots of which a subset moved coherently (i.e., are
the coherently-moving dots going to the right or to the left?). This field of
randomly moving dots changed in every trial. We manipulated decision bias by
varying the proportion of trials in which dots moved in one of the response
directions (left or right). For example, if for a certain block, dots move in
the left-ward direction for 90% of the trials, then participants have a strong
bias towards responding *left.* We found that as decision bias got stronger,
the amplitude of very fast brain waves (gamma oscillations) increased. In other
words gamma oscillations in electrodes over parietal cortex could, to some
extent, predict the magnitude of participants' decision bias. This agreed with
previous findings of Wyart & Tallon-Baudry (2009) in a decision making task
about consciously imperceivable stimuli. However, evidence in our experiment
was statistically fairly weak, possibly due to the fact that we could not
compare neural activity to a proper baseline. We therefore seek to replicate
this experiment in a setting where a better baseline can be defined.
An alternative way of inducing decision bias is with a pre-stimulus cue
(e.g., Forstmann et al, 2008). This cue tells the participant about the
probability that the dots are moving in a certain direction. The advantage of
such an approach is that decision bias is manipulated on a trial-by-trial
basis, rather than a block-by-block basis as in our previous experiment (van
Vugt, 2011). The research question of our proposed study is whether a decision
bias induced on a trial-by-trial basis leads to similar correlations between
decision bias and pre-stimulus gamma oscillations as when it is manipulated on
a block-wise manner, as we did in our previous experiment. And if such a neural
correlate of pre-stimulus bias exists, can this neural decision bias
represented by gamma oscillations be used to predict the decision bias
parameter in a mathematical model of decision making (Ratcliff, 1978).
Study objective
We would like to know whether pre-stimulus gamma oscillations can predict
decision bias in a perceptual decision making task.
Study design
To answer these questions, we will collect EEG a measurements while
participants engage in a perceptual decision making task (van Vugt et al,
2011). In this task, participants make repeated decisions about the direction
(left or right) of randomly moving dots. We will examine to what extent
pre-stimulus gamma oscillations can predict decision bias induced by
pre-stimulus cues.
Study burden and risks
The experiments will not entail any risk to the participants. The study is not
intended to benefit the subjects directly but subjects may find it interesting
to learn about how decisions manifest themselves in brain activity.
Postbus 407
9700 AK Groningen
NL
Postbus 407
9700 AK Groningen
NL
Listed location countries
Age
Inclusion criteria
Age 15-35, right-handed, normal vision.
Exclusion criteria
* Wearing braided hair (which makes recording of reliable EEG signals nearly impossible)
* Insufficient mastery of the Dutch language
* Neurological problems (including epilepsy)
* Use of drugs that may influence the task performance
Design
Recruitment
Followed up by the following (possibly more current) registration
No registrations found.
Other (possibly less up-to-date) registrations in this register
No registrations found.
In other registers
Register | ID |
---|---|
CCMO | NL38282.042.11 |