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Reward modulation of cognitive function: aging
RC interval
CT interval
reward cue
task cue
target
feedback
response
word
15 cent
TRIAL 4
high reward
task switch
le
le right
correct!
15 cent
incorrect!
0 cent
TRIAL 3
low reward
task repeat
arrow
le
1 cent
le right
correct!
1 cent
incorrect!
0 cent
TRIAL 2
low reward
task switch
1 cent
arrow
right
le right
correct!
1 cent
incorrect!
0 cent
TRIAL 1
(discarded)
15 cent
word
le
correct!
15 cent
le
incorrect!
0 cent
right
Figure 5.1 Task-switching paradigm with reward manipulation
Participants had to respond to incongruent arrow-word combinations, either by responding to the
direction of the arrow (i.e. <- or ->) or to the direction indicated by the word (“left” or “right”) with
a left or right button press. A task cue preceding the target indicated according to which task (arrow
or word) the participant had to respond on the current trial. The task performed on a particular trial
either changed unpredictably compared with the preceding trial (i.e. switch trial; arrow - word or word
- arrow) or remained the same (i.e. repeat trial; arrow-arrow, word-word). In addition we manipulated
the value of each trial on a trial-by-trial basis by means of a reward anticipation cue (i.e. 1 vs. 10 or 15
cents; table 1) (see also (Aarts et al., 2010; Aarts et al., 2015). Reward could be earned with a correct and
sufficiently quick response. Immediately following the response, feedback was given (e.g., “correct! 15
cents”). The cues and feedback were shown for 600 msec. RC interval: reward cue - task cue interval; CT
interval: task cue - target interval (table 5.1).
approved by the local ethics committee (CMO Arnhem-Nijmegen CMO
2008/159; 2009/058; 2010/402) and were in accordance with the Declaration of Helsinki.
Paradigm
All participants performed a task-switching paradigm with a reward manipulation (figure
5.1) (Aarts et al., 2010; van Holstein et al., 2011). The task was programmed and presented
using the Presentation® software (Neurobehavioral Systems, Inc.; ).
The test was preceded by 3 practice blocks. The first practice block (24 trials) contained the
task cue and target, followed by feedback (“correct”, “incorrect”); in the second practice block
(24 trials), reward cues were added. Finally, to account for inter-individual differences in
response speed and subsequent task difficulty, we used the correct responses during the third
practice block (32 trials), without reward or feedback, to determine each individual’s response
deadline for 4 trials-types (Arrow/Word x Switch/Repeat). Participants were instructed to