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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Retrospectively registered

Titles & IDs
Public title
Comparing two smartphone-based cognitive training strategies for improving healthy food choice in adults with overweight and obesity
Scientific title
Pilot feasibility trial of two smartphone-based cognitive training strategies for improving healthy food choice in adults with overweight and obesity compared with non-treated individuals
Secondary ID [1] 293418 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Overweight and obesity 305579 0
Condition category
Condition code
Diet and Nutrition 304803 304803 0 0
Mental Health 304804 304804 0 0
Studies of normal psychology, cognitive function and behaviour

Study type
Description of intervention(s) / exposure
This study is a 6-week pilot trial of two smartphone-based interventions (Arm 1: Approach-Avoidance training; Arm 2: Episodic Future Thinking) that aim to improve cognition (and therefore, healthy food choice) in 60 overweight or obese participants.

Intervention Arm 1 - Approach-Avoidance training. Participants allocated to Arm 1 will complete approach-avoidance training on a novel iPhone application (developed by the researchers). In this app, participants will be instructed to tilt their phone toward or away from themselves based on the format of a food image (i.e., portrait or landscape). These instructions will be counterbalanced. Image size increases when tilting toward (simulating approach) and decreases when tilting away (simulating avoidance). Each image (20 healthy; 20 unhealthy foods) is shown twice, which results in a total of 80 trials. Contingencies are manipulated to train approach of healthy (tilt: toward 90%; away 10%) and avoidance of unhealthy food (tilt: toward 10%; away 90%). The training will take approximately 5mins per day for one week. Participants completed the training on their smartphone daily for one week (7 sessions) and each session took approximately 5 minutes to complete. Participants completed the training outside of the laboratory. To assess intervention adherence, the number of sessions completed by each participant was recorded via the app. To improve adherence rates, participants are sent a daily push notification (via the app) at 12pm AEST as a reminder to complete the training.

Intervention Arm 2 - Episodic future thinking: A researcher will help participants to create three personalised episodic future thinking cues. Participants will be given a calendar and asked to: (1) list 3 future health goals they would like to achieve and (2) list 3 future events they anticipate in the following 4 weeks. The researcher uses open-ended questions to obtain location, time, emotion(s), and a context for the future events. Subsequently, the researcher helps the participant to pair their goals with their events to form an ‘EFT cue’ that encourages participants to imagine themselves achieving their health goals at their events. The development of the EFT cues will take place in a single 20 minute face-to-face session with the researcher at baseline. To improve adherence rates, participants will receive a daily text-message (via SEMA - an existing smartphone app) with their EFT cue (which will take approx. 5 mins to read) at 12pm AEST daily for one week. To assess intervention adherence, the number of text messages read by the participant was recorded via the SEMA app.
Intervention code [1] 299662 0
Treatment: Other
Intervention code [2] 299663 0
Comparator / control treatment
Control: wait-list (no treatment is administered to this groups but they complete the same assessments as the two intervention groups). Participants in the wait-list control group will be randomly allocated to receive one of the active interventions (approach-avoidance training or episodic future thinking) on completion of the 6-week follow-up session.
Control group

Primary outcome [1] 304018 0
Change in approach bias for healthy and unhealthy food cues as measured by behavioural performance on a cognitive task

Approach-avoidance task: A computerized joystick task used to measure approach bias. Participants begin by pressing the start button on the top of the joystick. A picture of a healthy food or an unhealthy food will appear in the centre of the screen. Participants are instructed to push or pull the joystick according to whether the picture is presented in portrait or landscape format. The instructions are counterbalanced (i.e., half of the participants pull portrait pictures and push landscape, and vice versa). When participants pull the joystick, the picture size increases (simulating approach), while pushing the joystick decreases the picture size (simulating avoidance). Participants are asked to respond as quickly and accurately as possible. During the task, each of the 40 images (20 healthy food and 20 unhealthy food) will be shown twice, once in the format participants are instructed to pull and once in the format they are instructed to push, resulting in 80 trials. Participants will push and pull the healthy and unhealthy food pictures equally often. The task will take approximately 5-10 minutes.
Timepoint [1] 304018 0
Baseline, post-training (1 week after baseline), and 6-week follow-up (6 weeks after baseline)
Primary outcome [2] 304019 0
Change in proportion of healthy food choices (hypothetical)

Food choice task: Participants will be presented with 16 photographed foods (8 unhealthy and 8 healthy) in a 4 x 4 square grid on a computer touchscreen. Participants will be asked to select eight of the foods that they would like to consume within a 15 second timeframe. Food choice will be measured as the proportion of healthy food relative to total foods chosen during the task. The task will take approximately 5 minutes.
Timepoint [2] 304019 0
Baseline, post-training (1 week after baseline) and 6-week follow-up (6 weeks after baseline)
Primary outcome [3] 304073 0
Change in delay discounting rates for money and food rewards as measured by behavioural performance on a cognitive task

Money and Food Delay Discounting Task: Participants have to indicate their preferences in a series of choices for two hypothetical outcome types: immediate (smaller amount) versus delayed (larger amount) food and immediate versus delayed money. Participants made choices involving either relatively small maximum amounts of food (1 serving) and money ($10) or for relatively large maximum amounts of food (10 servings) and money ($100).
Timepoint [3] 304073 0
Baseline, post-training (1 week after baseline) and 6-week follow-up (6 weeks after baseline)
Secondary outcome [1] 340727 0
Change in body mass index (BMI): Participants’ height and weight was measured using digital body weight scales and a standard tape measure in a face-to-face session.
Timepoint [1] 340727 0
Baseline and 6-week follow-up (6 weeks after baseline)
Secondary outcome [2] 340728 0
Engagement with the training: Engagement with the training (motivation to complete training, ease of use and enjoyment) was assessed with a 5-point Likert scale ranging from 1 (strongly disagree) to 5 (strongly agree).
Timepoint [2] 340728 0
Post-training (1 week after baseline)
Secondary outcome [3] 340856 0
Change in inhibitory control

Stop signal task: Measure of reaction time and motor inhibitory control. Participants have to respond as quickly as possible, but on some trials they must withhold their response if they hear the stop signal. The dependent measure of this task is the mean stop-signal reaction time, which measures the speed of the inhibitory process, and is calculated by subtracting the stop-signal delay from the mean response time to go trials.
Timepoint [3] 340856 0
Baseline, post-training (1 week after baseline) and 6-week follow-up (6 weeks after baseline)
Secondary outcome [4] 340857 0
Training compliance was measured by the number of training sessions completed or notifications received (both indicated via an in-built feature of each of the smartphone apps).
Timepoint [4] 340857 0
Post-training (1 week after baseline)

Key inclusion criteria
Excess weight adults: Aged between 18 and 45; Body Mass Index (BMI) between 25 kg/m2 – 40kg/m2
Minimum age
18 Years
Maximum age
45 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
1. Do not own an iPhone: Participants need an iOS smartphone (iPhone) as the smartphone applications are only compatible with the iOS operating system
2. Undertaking other weight loss programs
3. Pregnancy
4. Lost more than 4.5kgs in the last 6 months
5. Currently taking medications that may affect or be affected by weight loss
6. Illnesses associated with excess weight (e.g., diabetes)
7. Self-reported history of eating disorders, brain trauma, neurological or substance use disorders
8. Self-reported current psychiatric diagnosis (e.g., depression)
9. Vegan/Vegetarian
10. Smoker

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation is not concealed
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software (i.e. computerised sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Mixed-design repeated measures models will assess the impact of group (AAT, EFT, wait-list control) x time (baseline, post-training, 6-week follow-up) on change in cognitive measures (approach bias, delay discounting, inhibitory control), healthy food choice and BMI.

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)

Funding & Sponsors
Funding source category [1] 298041 0
Name [1] 298041 0
Monash University
Address [1] 298041 0
Wellington Road, Clayton, 3800, Victoria, Australia
Country [1] 298041 0
Primary sponsor type
Monash Institute of Cognitive and Clinical Neurosciences, Monash University
Building 17, 18 Innovation Walk, Monash University, Wellington Road, Clayton, 3800, Victoria
Secondary sponsor category [1] 297121 0
Name [1] 297121 0
Address [1] 297121 0
Country [1] 297121 0

Ethics approval
Ethics application status
Ethics committee name [1] 299068 0
Monash University Human Research Ethics Committee
Ethics committee address [1] 299068 0
Monash University
Level 1, Building 3e, Clayton Campus
Wellington Rd
Clayton VIC 3800
Ethics committee country [1] 299068 0
Date submitted for ethics approval [1] 299068 0
Approval date [1] 299068 0
Ethics approval number [1] 299068 0

Brief summary
Obesity is a major health concern both globally and in Australia. A key contributor to excess weight gain is unhealthy food choices, which are deeply ingrained and difficult to change due to underlying cognitive mechanisms. Two of these mechanisms are approach bias (a tendency to think about and move toward unhealthy foods) and steep delay discounting (a preference for smaller, immediate rewards over larger, delayed rewards), which can be modified using cognitive training techniques, i.e., approach-avoidance training (AAT) and episodic future thinking (EFT).

This study aims to test the effects of these two cognitive training techniques (i.e., AAT and EFT) compared to a control (i.e., no-training) group, on cognition (approach bias, delay discounting), and behaviour (healthy food choices) in people with excess-weight. The primary aim is to compare each of the active interventions with a control to establish their cognitive mechanisms and determine which of them has a greater impact on food choice.

It is hypothesized that compared to participants in the control condition, participants in the: 1) AAT condition will show a greater increase in approach bias for healthy food and a decrease in approach bias for unhealthy food, 2) EFT condition will show a greater decrease in delay discounting rates, and 3) AAT and EFT condition will choose a greater proportion of healthy foods.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 79182 0
A/Prof Antonio Verdejo-Garcia
Address 79182 0
School of Psychological Sciences (Building 17) - Faculty of Medicine, Nursing and Health Sciences - Monash University - Wellington Road - Clayton - Victoria 3800
Country 79182 0
Phone 79182 0
+61 3 99055374
Fax 79182 0
Email 79182 0
Contact person for public queries
Name 79183 0
A/Prof Antonio Verdejo-Garcia
Address 79183 0
School of Psychological Sciences (Building 17) - Faculty of Medicine, Nursing and Health Sciences - Monash University - Wellington Road - Clayton - Victoria 3800
Country 79183 0
Phone 79183 0
+61 3 99055374
Fax 79183 0
Email 79183 0
Contact person for scientific queries
Name 79184 0
A/Prof Antonio Verdejo-Garcia
Address 79184 0
School of Psychological Sciences (Building 17) - Faculty of Medicine, Nursing and Health Sciences - Monash University - Wellington Road - Clayton - Victoria 3800
Country 79184 0
Phone 79184 0
+61 3 99055374
Fax 79184 0
Email 79184 0

No data has been provided for results reporting
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary