This project has three research aims:
Investigate whether stronger habitual behavior and increased susceptibility to the
conflict between habitual and goal-directed control are associated with SUD
Investigate whether PIT is more of a habitual or a goal-directed process.
Replicate the previous findings that moderate to severely dependent AUD patients
show a stronger PIT effect in contrast to the control group The experiment will be
conducted in 90 AUD patients and 90 age and gender-matched controls. Participants
will perform the AST task over two consecutive days, and during the second day, they
will also perform the single-lever PIT task. In the AST, participants need to press
four keys according to the cue location; two keys are associated with high reward,
while the other two are associated with low reward in case of correct and timely
responses. The explicit goal is to maximize the reward. While in half of the trials
the cues are presented in a random order, in the other half of the trials,
participants repeatedly perform a fixed action sequence of 12 elements (habit
condition). The degree of action sequence chunking (i.e. automation) is assessed via
the differences in error rates and reaction times between the random and fixed order
condition (habit parameter). Importantly, 15% of all trials are dual- target trials.
In these, the goal-directed system (press high reward key) and the action sequence
(press sequence key) can either be in line (congruent trials) or in conflict
(incongruent trials) with each other. Thus, the interference between goal-directed
and habitual control can be tested.
The single-lever PIT task consists of four phases. In the instrumental task, participants
need to learn which shells to collect or leave in order to gain as much money as
possible; the correct choice is probabilistically rewarded in 80% of all times. During
the Pavlovian conditioning phase, colorful fractals are presented in the back of the
screen, which have been passively paired either with monetary loss, no change or monetary
gain, i.e. they act as positively valued, neutral or negatively valued cues. During the
transfer phase, participants were instructed to perform the instrumental task as they
have done previously. These fractals thus act as independent, Pavlovian conditioned
background stimuli and interact with instrumental behavior in the unrelated task to
collect the correct shells. To avoid further learning, this transfer part will be
conducted under nominal extinction. Finally, query trials, in which one of two pictures
will have to be chosen, will be used to assess the relative cue value.
The participants will additionally perform a Counting Stroop task and a No-go Simon task.
In the Stroop task, either one, two, three or four identical digits from 1 to 4 are
shown. Number and denotation of digits are either congruent (1, 22, 333, 4444; 80 trials)
or incongruent (111, 2222, 3, 44; 80 trials). Subjects have to indicate how many digits
were shown. In the No-go Simon task, the investigators will show arrows either pointing
to the left or right. The arrow can either be shown on the left or the right side of the
display. In congruent trials, direction and position are the same, whereas they differ in
incongruent trials. Participants have to indicate the direction of the arrow and ignore
the position. 20% of trials are No-go trials, indicated by bold arrows. Here subjects
have to always withhold a response (inhibition task).
Expected results:
Hypothesis a: The investigators hypothesize an increased habitual tendency and
susceptibility to conflict, i.e. interference between habitual and goal-directed control
as assessed with the AST in AUD participants. More specifically, the investigators
hypothesize that the AUD participants will perform the fixed sequence faster and with
fewer errors on the second day of AST. Moreover, in contrast to the control group, AUD
participants will choose the high reward keys less often in incongruent trials (when the
goals-directed control and the habitual action sequence are in conflict with each other),
indicating a shift from goal-directed to habitual control.
Hypothesis b: Given that the allocation of top-down control is needed for overcoming
interference by Pavlovian cues and exhibiting more goal-directed control, the
investigators expect that participants with stronger PIT effect (lower interference
control) also acquire habits more easily and show increased habitual control.
Additionally, the investigators hypothesize that the participants with a higher PIT
effect will exhibit a shift from goal-directed to habitual control, as indicated by a
lower frequency of high reward keys in incongruent trials. As a general process, these
associations should be observable in both, the AUD and the control group.
Hypothesis c: As a replication, the investigators expect the AUD group to show a stronger
PIT effect in contrast to the control group.
Hypothesis d: Both Interference costs (i.e. increased ER in instrumental responses)
during PIT and interference costs between goal-directed and habitual behavior will be
associated with interference costs at the stimulus level (Stroop task) and at the
response level (No-go Simon task), and these costs will also be correlated with the ER
during response inhibition (No-go Simon task).