Script Author: Katja Borchert, Ph.D. (katjab@millisecond.com), Millisecond
Millisecond thanks Leonardo Tadonio for providing the Italian translations!
Created: March 22, 2018
Last Modified: December 02, 2024 by K. Borchert (katjab@millisecond.com), Millisecond
Script Copyright © Millisecond Software, LLC
This script implements a procedure to study cognitive effort in relationship to reward. The implemented procedure was used by Botvinich et al (2009) study neural analogues of effort discounting (the decline of reward value with increasing effort) via fMRI.
Botvinick MM, Huffstetler S, McGuire JT (2009) Effort discounting in human nucleus accumbens. Cogn Affect Behav Neurosci 9:16–27.
18 minutes
Participants are presented digits (1-9, no 5) and, depending on the color of the digit, are asked to perform parity judgments (is BLUE digit odd or even?) or magnitude judgments (is YELLOW digit greater than 5?). Parity and magnitude judgment trials run under 2 different demand conditions: 1. Low demand condition: no switching between tasks within a block of 10 trials (parity-only, magnitude-only) 2. High demand condition: alternating between parity and magnitude tasks within a block of 10 trials At the end of each block, the computer randomly decides (with default constraints) if the block should be rewarded or not.
Rewards are purposefully NOT tied to performance nor demand condition in this task. Effort in this task is manipulated through different external task demands as opposed to performance incentives. As low demand conditions would likely result in higher pay (as they are easier and likely result in faster reaction times and lower error rates) performance incentive rewards would likely result in different expectancies for low and high demand blocks and therefore might confound effort for those two different conditions.
The script runs 20 blocks total (5 parity blocks, 5 magnitude blocks = low demand, 10 alternate blocks = high demand) and concludes with an optional 'effort/fair pay' survey.
A control condition (see specifics below) can be run by choosing even groupnumbers (odd groupnumbers run the experimental group).
2 task demand conditions: low demand vs. high demand task
2 experimental condition: experimental group (odd groupnumbers) vs. control group (even groupnumbers)
low demand: only one task is performed (no switching)
- parity: decide if the (blue) digit is odd or even
- magnitude: decide if the (yellow) digit is smaller or greater than 5
high demand: the low demand tasks alternate (the color of the digit is the cue which task to perform);
the starting condition (parity vs. magnitude) is randomly selected
Practice Session(s):
- one practice session runs: one block parity (10 trials), one block magnitude (10 trials), and 2 blocks alternate (10 trials each)
(= 40 practice trials per session) in random order (constraint: first practice session runs the alternate blocks at the end)
- practice session is repeated if performance across all blocks < 80% correct (default, can be edited under section Editable Parameters)
- practice session ends after a maximum number of 5 repeats (default, can be edited under section Editable Parameters)
regardless of performance and participants move on to the test
This set-up differs from Botvinick et al (2009)
Test Blocks: 20* test blocks (5 parity, 5 magnitude, 10 alternate = 10 low demand blocks, 10 high demand blocks)
- each block runs 10 trials (digits are randomly chosen)
- each block has a 50/50 reward chance with the following default constraints ( can be turned off under section Editable Parameters):
1. no more than 6 (out of 10) low (high) demand blocks are rewarded
2. no fewer than 3 (out of 10) low (high) demand blocks are rewarded
• Botvinick et al (2009) ran 18 blocks per session. For this script, a block number was selected
that was divisible by 4 to ensure that the same number of parity and magnitude blocks would be run
in the same session.
Block Sequence:
Reminder -> Get Ready (2000-8000ms, randomly sampled from list.delays)
-> cue trial (2000ms)
-> 10 Trials (digit stays on for max. 1500 (max responsetime) with an interstimulus interval of 500ms) ->
Payment Delay (2000-8000ms, randomly sampled from list.delays) -> Reward Notice (2000ms)
-> interblock interval (2000-8000ms, randomly sampled from list.delays)
Optional 'Effort' Survey:
2 questions:
(1) effort (order of answer choices is randomly decided)
(2) fair pay for (a)low demand and (b) high demand blocks (position of a/b is randomly determined)
Experimental vs. Control Group: Differences
- experimental group is told that the computer randomly selects at the end of each block
whether the block would be rewarded with pay by announcing "deciding your pay" and then
presenting an "$" (pay) vs. "X" (no pay).
The control group is told that their participation would be rewarded with $20 at the end of
the task. Instead of the message "deciding your pay" they see "calculating, please wait"
followed "S" and "K". They are told these letters are irrelevant but they should pay
attention nonetheless to not miss the next block.
provided by Millisecond - can be edited under section Editable Stimuli
The instructions are provided by by Millisecond and are not original to Botvinick et al (2009).
They can be edited under section Editable Instructions.
File Name: effortdiscountingtask_summary*.iqdat
| Name | Description |
|---|---|
| inquisit.version | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| startDate | Date the session was run |
| startTime | Time the session was run |
| subjectId | Participant ID |
| groupId | Group number |
| sessionId | Session number |
| elapsedTime | Session duration in ms |
| completed | 0 = Test was not completed 1 = Test was completed |
| expCondition | 1 = experimental group; 2 = control group |
| practiceSessionCount | Counts the number of practice sessions run one practice session runs 1 block parity, 1 block magnitude, 2 blocks alternate |
| list.accuracyPractice.mean | The proportion correct during the practice sessions (across all four blocks of a practice session) |
| practiceSessionCount | Counts the number of practice sessions run one practice session runs 1 block parity, 1 block magnitude, 2 blocks alternate |
| propCorrectPractice | The proportion correct across the last practice session run (across the 4 blocks) |
| propCorrect | Overall proportion correct across all test blocks |
| meanRT | Mean correct latency (in ms) across all test blocks |
| propCorrectParity | Proportion correct across all parity-only test blocks |
| meanParity | Mean correct latency (in ms) of parity-only test trials |
| propCorrectMagnitude | Proportion correct across all magnitude-only test blocks |
| meanMagnitude | Mean correct latency (in ms) of magnitude-only test trials |
| propCorrectLD | Proportion correct across all low demand test blocks |
| meanRTLD | Mean correct latency (in ms) of trials in low demand test blocks |
| propCorrectHD | Proportion correct across all alternate (high demand) test blocks |
| meanRTHD | Mean correct latency (in ms) of trials in alternate (high demand) test blocks optional survey responses (see settings of parameters.runEffortSurvey) radioButtons.blockeffort.response: response to optional effort question (see section Editable Parameters) 1 = more effort of low demand blocks (same color digits) 2 = more effort of high demand blocks (different color digits) |
| radioButtons.playaGain.response | "yes" vs. "no" |
| textbox.fairpayLowDemand.response | Response (in monetary unit) to fair pay to low demand blocks |
| textbox.fairpayHighDemand.response | Response (in monetary unit) to fair pay to high demand blocks |
File Name: effortdiscountingtask_raw*.iqdat
| Name | Description |
|---|---|
| build | Inquisit version number |
| computer.platform | Device platform: win | mac |ios | android |
| date | Date the session was run |
| time | Time the session was run |
| subject | Participant ID |
| group | Group number |
| session | Session number |
| expCondition | 1 = experimental group; 2 = control group |
| phase | "practice" vs. "test" |
| practiceSessionCount | Counts the number of practice sessions run one practice session runs 1 block parity, 1 block magnitude, 2 blocks alternate |
| blockCode | Name of the current block |
| blockNum | Number of the current block |
| trialCode | Name of the current trial |
| trialNum | Number of the current trial |
| countLD | Counts the number of low demand (parity-only, magnitude-only) blocks run |
| countHD | Counts the number of high demand (alternate) blocks run |
| demand | 1 = low demand condition; 2 = high demand condition |
| cue | Itemnumber of the condition cue (1 = bluedisc (parity); 2 = yellowdisc (magnitude); 3 = mixed disc) |
| paymentCue | 1 = reward cue ($) should be selected; 2 = non-reward cue (X) should be selected |
| paymentDelay | Stores the randomly selected delay of the reward announcement (in ms) |
| presentedStim | For parity/magnitude trials: contains the presented digit (for other trials: stores first stimulus to appear) |
| response | The participant's response (scancode of response button) 30 = A (left) 38 = L (right) 57 = spacebar |
| correct | Accuracy of response: 1 = correct response; 0 = otherwise |
| latency | The response latency (in ms); measured from: onset of digit |
| total | Stores the total won during the test session |
| countRewardsLD | Counts the number of reward blocks in the low demand condition |
| countRewardsHD | Counts the number of reward blocks in the high demand condition |
| list.accuracyPractice.mean | The proportion correct during the practice sessions (across all four blocks of a practice session) |
The procedure can be adjusted by setting the following parameters.
| Name | Description | Default |
|---|---|---|
| runEffortSurvey | True (1): at the end of the task the participants received questions in regard to 'effort' and 'fair pay' (default) false (0): no survey is added to the end of the tas | |
| digitSize | The proportional sizing (relative to canvas height) of the digits | 15% |
| taskCueSize | The proportional sizing (relative to canvas height) of the task cue | 30% |
| paymentCueSize | The proportional sizing (relative to canvas height) of the payment cue | 20% |
| minPracticeAcc | The minimum proportion correct that needs to be hit before participants can move from practice to test session (default: 0.8) | |
| maxPracticeBlockRepeats | The maximum number practice sessions run before participants moves on to the test regardless of performance (default: 8) | |
| reward | The offered reward (in $) | 1 |
| paymentConsTraints | False: script randomly decides for each block whether it's a reward or a non-reward block with p(reward) = 0.5 true (default): script randomly decides for each block whether it's a reward or a non-reward block with p(reward) = 0.5 with the added constraints that 1. no more than 6 (out of 10) low (high) demand blocks are rewarded 2. no fewer than 3 (out of 10) low (high) demand blocks are rewarded (see Botvinick et al, 2009, p.16 for the description of constraints implemented on 18 test blocks) | |
| ctrlPayment | Payment for control condition, paid at the end of the task | $20 |
| reminderDuration | The duration of the task reminders (in ms) that are presented without key instructions at the beginning of each block (default: 2000) | |
| cueDuration | The duration (in ms) of the cue | 2000 |
| digitDuration | The duration (in ms) of the digit ; participants have the entire duration to respond | 1500 |
| iti | The duration (in ms) of the intertrial interval | 500 |
| paymentCueDuration | The duration (in ms) of the payment cue | 2000 |
| parityColor | Stores the color of the parity cue | blue |
| magnitudeColor | Stores the color of the magnitude cue if the colors are changed, instructions as well as cues need to be updated accordingly | gold |
| leftResponseKey | The left response key | "A" |
| rightResponseKey | The right response key | "L" |