DOI: 10.34894/vip3ua
title: Exploring the Reward System: A Dual Investigation into Substance Use and Overeating
title: Master Thesis Project ReMa-IDA 2023-2024

description: When the reward systems are dysregulated, some individuals may
turn to the excessive use of natural rewards, such as eating, while
others may resort to artificially rewarding activities, such as
substance use (Barson et al, 2012). While substance use and
overeating have been both identified as maladaptive coping
mechanisms employed to alleviate negative emotional states, the
role of positive emotions remains an understudied domain. This
project aimed to investigate:
&lt;ol&gt;
&lt;li&gt;the role of positive urgency - higher impulsivity in response
to positive emotions - and sensation-seeking in the degree
of substance use in university students, employing heart
rate variability as a reward sensitivity biomarker;
&lt;li&gt;the role of the positive emotion of joy in food intake in
university students, using skin conductance as the potential
underlying mechanism.
&lt;/ol&gt;
description: Method<br><br>
<b>Procedure</b><br><br>
All data was collected during one in-person laboratory session in the
GO-Lab, Tilburg University. Participants were recruited via the SONA
system used at Tilburg University from the English-speaking student
population of BSc Psychology. At the beginning of the laboratory
session, participants provided anthropometric information by
standing on the weight scale and under the stadiometer. Further,
participants filled in questionnaires and watched an emotion
induction video in Qualtrics and completed the probabilistic reward
task in Inquisit, on the GO-Lab’s computer. During the resting
baseline, emotion induction video, and Inquisit task, the participants’
physiological data (electrocardial and electrodermal activity) was
recorded. Prior and after the bogus taste task, food intake was
measured by weighing all four the food items in separate bowls on a
kitchen scale – before and after the task (see Codebook for used
food items). After the laboratory session, physiological data was
pre-processed in AcqKnowledge (v.5.0) on Go-Lab’s computers.
<br><br>
<b>Measures Overview</b><br>
Questionnaires included:

Demographic information (age, assigned sex at birth);
Anthropometric information (weight and height);
Use of prescription medication;
Lifestyle information (alcohol and substance use);
DEBQ (eating styles; Van Strien et al., 1986);
PHQ9 (depressive symptoms);
Positive Urgency Subscale of UPPS-P Scale (Whiteside, & Lynam,
2001);
Brief Sensation-Seeking Scale (BSSS; Hoyle et al., 2002);
Current mood items;
Bogus Taste Task items.

Pre-processed physiology data included:

mean RMSSD (electrocardial activity) during resting baseline and
the probabilistic reward task in Inquisit;
number / count of NSSCR (electrodermal activity; non-specific skin
conductance responses) during resting baseline and emotion
induction task;
mean SCL (electrodermal activity; skin conductance level) during
resting baseline and emotion induction task.

Bogus Taste Task measurements included:

Weight of all four food items before and after the task;
Caloric intake of all food items before and after the task;
Food intake (total caloric consumption of all food items).

Probabilistic reward task included:

logD (measure of Discriminability);
logB (measure of Response Bias);
mean response latencies;
proportion correct (in)frequently rewarded mouth trials;
number of rewards given out.

<b>NB</b>: Please refer to Codebook (file name:
“Codebook_Reward-System_Substance-Use_Overeating”) and
“Qualtrics Materials: Instructions & Survey” for a complete overview
of the used measurements.
<br><br>
Universe: Sample of 74 individuals (English-speaking students of BSc
Psychology at Tilburg University; 72 and 71 with complete data,
respectively, per research aim) who completed the questionnaires,
anthropometric measures, cognitive and behavioral experiments and
provided physiological data.
<br><br>
Country / Nation: the Netherlands
description: <b>Data files</b><br>
 Excel dataset file:
“Substance-Use_Overeating_Dataset_Anonymized.xlsx”<br>
Description: This anonymized Excel data file contains all variables
used for the project, obtained by merging outputs from multiple
sources of data collection: Qualtrics, preprocessing of physiological
measures, imputed anthropometric measures, and generated output
from Inquisit, food intake variables. The variable names are detailed
in the Codebook (see Supp. materials).<br><br>
SPSS syntax file: Substance-Use_Analysis.sps<br>
Description: This file contains the data analysis of the first research
question of the project, related to substance use, sensation-seeking,
positive urgency and two indices of heart rate variability.
<br><br>
R (v.2022.12.0) syntax file: Overeating_Analysis.R<br>
Description: This file contains the data analysis on the second
research question of the project, related to joy induction, food intake
and two indices of electrodermal activity.
<br><br>
<b>Supplemental material</b><br>
File name:<br>
“Codebook_Reward-System_Substance-Use_Overeating.pdf”
This file contains the overview of all the variables in the Excel data
file.
<br><br>
“Qualtrics Materials: Instructions & Survey.pdf”<br>
This file contains the instructions and wording of all the items and
questionnaires in the order presented to the participants, as well as
the informed consent forms (empty), and the information letter.
<br><br>
Probabilistic Reward Task (Inquisit task): see
https://www.millisecond.com/download/library/probabilisticrewardtask
<br><br>
“Data Collection Protocol.pdf”<br>
This file contains the step-by-step protocol for laboratory visit data
collection.

<br><br>
“Protocol Pre-Processing AcqKnowledge.pdf”<br>
This file contains the step-by-step protocol for physiological data
pre-processing.
<br><br>
<b>Structure data package</b><br>
The data package contains two separate folders. A “Data and
analyses” folder containing the data files and a “Supplementary
materials” folder containing the supplementary materials.