Multitasking Behavior and Neural Representations Associated With Multitasking AbilityNCT06436209
Cognitive Control & the Functional Organization of the Frontal Cortex
A study testing Multitask Practice Intervention (MPI) and Single-task Practice Intervention (SPI) in people with Multitasking Behavior and Neural Representations Associated With Multitasking Ability and Healthy Volunteers, run by Brown University at 1 site in United States.
Trial summary
The goal of this basic experimental clinical trial is to understand the effect of multitasking practice on the structure of neural representations of tasks in the human lateral prefrontal cortex and control brain regions. Read more about this study
- Who is it for?
- Ages 18 to 35 yearsHealthy volunteers can take part
- Conditions the study is for
- Multitasking Behavior and Neural Representations Associated With Multitasking Ability, Healthy Volunteers, Executive Function
- What is being tested?
- Multitask Practice Intervention (MPI) and Single-task Practice Intervention (SPI)
- Type of treatment
- Lifestyle or therapy programme
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 1 siteUnited States
- Study dates
- 27 Mar 2024to 31 Jul 2026
- Phase
- Interventional
- Are there results?
- Not yet: the study is under way
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 35 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Normal or corrected to normal vision.
Who cannot join
- Left handedness
- Presence or history of neurological or psychiatric disorders
- Usage of brain related medications
- Previous head injury and time spent unconscious
- Any implanted medial fragment or device in the body of the participant.
- Tattoos above the neck
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- Injury to the eye or other body part involving a metallic object or fragment.
- Welding, grinding, or cutting of metal in lifetime of participant without usage of safety protection glasses.
- injury to the participant by a metallic object or foreign body (e.g., BB, bullet, shrapnel, etc.)
- Pregnancy or possibility of pregnancy
- Implants or devices including:
- Electronic implant or device, Magnetically-activated implant or device, Cardiac pacemaker, Implanted cardioverter defibrillator (ICD), Aneurysm clip(s), Neurostimulation system, Spinal cord stimulator, Internal electrodes or wires, Bone growth/bone fusion stimulator, Cochlear, otologic, or other ear implant, Insulin or infusion pump, Implanted drug infusion device, Any type of prosthesis (eye, penile, etc.), Heart valve prosthesis, Eyelid spring or wire, Artificial or prosthetic limb, Metallic stent, filter, or coil, Shunt (spinal or intraventricular), Vascular access port and/or catheter, Radiation seeds or implants, Swan-Ganz or triple lumen catheter, Medication patch (Nicotine,Nitroglycerine), Any metallic fragment or foreign body, Wire mesh implant, Tissue expander (e.g., breast), Surgical staples, clips, or metallic sutures Joint replacement (hip, knee, etc.) Bone/joint pin, screw, nail, wire, plate, etc. IUD or diaphragm, Dentures or partial plates, Tattoo or permanent makeup above the neck, Body piercing jewelry that can not be removed, Breathing disorder, Motion disorder or tremors, Claustrophobia, Hearing aid
Trial locations and contacts
1 site in 1 country. Contact the study team or a site near you to ask about taking part.
United States1 site, 1 recruiting
- Recruiting
Metcalf Research Building, Brown University & MRI Research Facility, Brown University
Providence, Rhode Island, 02912
Defne Buyukyazgan, BA
David Badre, PhD
About this study
The goal of this basic experimental clinical trial is to understand the effect of multitasking practice on the structure of neural representations of tasks in the human lateral prefrontal cortex and control brain regions. The main question it aims to answer is: What changes in neural representational structure predict improvements in multitasking behavior due to multitasking practice? Healthy human participants will learn two independent tasks, each mapping a set of stimuli to motor responses based on different rules. Participants will be randomized to one of two interventions. Participants assigned to the multitask practice intervention (MPI) will practice multitasking the two tasks over multiple days. Those assigned to the single-task practice intervention (SPI) will instead practice each task separately while controlling for the total number of practice opportunities associated with each task across the interventions. Both before and after the practice, the ability of all participants to perform both tasks simultaneously will be behaviorally measured using a well-established psychological refractory period (PRP) paradigm, and their neural representations will be measured using functional MRI while they perform the two tasks. Researchers will then compare improvements in multitasking behavior across the two groups, as well as changes in neural representational geometry of the tasks in the lateral prefrontal cortex and control brain regions, and test whether multitasking training is associated with specific changes in neural representations in the lateral prefrontal cortex.
Read the detailed description
Background and Study Rationale:
Human performance on a task deteriorates when it is performed concurrently with another task. This multitasking cost has been attributed to competition for shared computational or biological resources and there is considerable debate in the field about the specific nature of these putative resources. Extensive multitasking practice is known to reduce, and sometimes, abolish these costs. These practice-related gains have been attributed to changes in central processing, more efficient task scheduling, or the learning of specialized task representations. The human prefrontal cortex is critical to flexible cognitive control of behavior, and is involved in representing tasks. However, it remains unknown what effect multitasking practice has on prefrontal task representations. In this study, we will directly address a gap in our knowledge by testing the link between multitasking costs and the geometry of neural manifolds representing task inputs in the lateral PFC.
Study Design:
Overview:
This study is a single-center, randomized controlled trial designed to examine the effect of multitask practice on multitasking behavior, the geometry of neural representations of tasks in the lateral prefrontal cortex and the relationship between these effects. A total of 60 healthy subjects are planned, 30 subjects being randomized to each, the multitask practice group (MPG), and the single task practice group (SPG). Baseline and endline assessments of multitasking behavior and neural representations in lateral PFC with fMRI will be conducted in all subjects.
Study Treatments:
Single-task practice treatment:
The single-task practice treatment will involve 3 sessions of practice during which subjects will practice instructed tasks in individual task blocks. Up to 48 blocks of practice will be performed. Subjects will be given feedback at the end of each block on their accuracy and speed of responding and they will be given an improvement target.
Multitask practice treatment:
The multitask practice treatment will involve 3 sessions of practice during which subjects will practice instructed tasks in the psychological refractory period paradigm. Up to 48 blocks of practice will be performed. Subjects will be given feedback at the end of each block on their accuracy and speed of responding and they will be given an improvement target.
Subject Selection:
Subjects will be recruited from the Providence community. Subjects will be screened over a phone call. Inclusion criteria include right-handedness, age between 18 and 35, and normal or corrected-to-normal vision. Exclusion criteria include history of psychiatric or neurological deficits and MR contraindications. Consenting procedures will be conducted in person during Study Session 1 and continuing consent will be periodically obtained during all lab Study visits.
Random Assignment:
Up to 60 eligible patients will be randomly assigned to SPG or MPG treatment groups in a 1:1 ratio by using a random number generator coded in MATLAB. Neither the experimenters nor the study subjects, will be blinded to the assignment.
Study Structure:
A total of 14 study sessions are planned for each subject. Study session 1 will be employed for informed consent, scheduling and familiarization with study tasks. Baseline evaluations will take place during study sessions 2 through 5. Treatment will be administered during study sessions 6 through 8 during which subjects will receive either 3 sessions of multi-task practice (MPG) or 3 sessions of single-task practice (SPG). Endline evaluations will take place during study sessions 9 through 12. Detailed descriptions of each Study session and all paradigms used for measurements are given below.
Behavioral paradigms:
All behavioral task paradigms will be implemented using Psychtoolbox 3 in MATLAB or in JSPsych. All tasks involve responding to visual objects presented on a computer screen with keypresses either on a keyboard or on a response box. Visual objects will vary along 4 dimensions - shape (square or circle), circle (orange or blue), pattern (dotted or striped) or size (small or large). Along with the visual object, a response panel consisting of the symbols @ and #. Subjects will be introduced to three different tasks: the shape task, color task and the pattern task. In each task, they will make a binary classification of the visual object relying on the relevant task feature (e.g. color in the color task). Each binary class will be associated with one of two categories associated with the @ and # symbols. Subjects will then select the response key associated with the relevant symbol. The left-right position of the two symbols will be varied randomly from trial to trial such that the position would be the same as the previous trial on approximately 50% of the trials, and each trial-type was associated with an equal number of left and right responses.
Single task paradigm: In the single-task paradigm, visual objects will be presented for up to 2.2 s. Responses deadline is 2.2s. Inter-trial interval will be 1 s. Trials are presented in pure single-task blocks with 64 trials per block.
Mixed tasks paradigm: In the mixed tasks paradigm, visual objects will be presented for up to 2.2 s. Response deadline is 2.2s. Inter-trial interval will be jittered between 2 and 10 seconds. Trials of multiple task types will be presented in the same block, with a word cue identifying the task to be performed on every trial.
Psychological Refractory Period paradigm: In the PRP paradigm, two visual objects will be presented on every trial, one in the upper half of the screen, and the other in the bottom half of the screen. Visual objects will be presented with a stimulus onset synchrony (SOA) varying between 50 ms and 1.5 s. Trial length will be up to 3 s. Response deadline will be 3 s for responding to both visual objects. Inter-trial interval will be either 1 s (behavioral blocks) or jittered between 2 and 10 seconds (MRI blocks). Subjects will be instructed to perform the tasks in a specific order (e.g. Color, then Shape), responding to the first stimulus that appears with the rule associated with the first task in the order and to the object that appears second. A total of 3 different task orders will be presented to subjects (e.g. Color -> Shape, Shape -> Color and Color -> Pattern) and these orders will be counterbalanced across subjects such that each task has placed every role equally in each treatment group. All task orders will be administered during both baseline and endline.
MRI Protocol:
Each subject will under MRI procedures during Study Visits 2, 3, 9 and 10. Each visit will last 2 hrs during which subjects will first be provided refresher instruction on the behavioral tasks before undergoing MRI for 1 hr. During each 1 hr MRI scanning session, subjects will first be screened for metal, briefed on safety procedures and motion minimization requirements, and then situated on the scanning table in a supine position. Their head will be stabilized with soft padding, and their ears will be protected from MR noise with ear plugs. Subjects will view a computer screen through a mirror installed on a headstage and will be provided with two response boxes for performing the tasks and an emergency buzzer for communicating with the experimenters and radiographers on duty. They will then undergo a multiple echo MPRAGE scan (repetition time (TR) = 2530 ms, echo times (TE) = 1.69, 3.55, 5.41, and 7.27 ms, flip angle = 7 degrees, 176 sagittal slices, 1 × 1 × 1 mm voxels) for 6 minutes during which they may close their eyes. Following this, subjects will undergo 5-10 runs of Echo Planar Imaging (TR = 1000 ms, TE = 32.6 ms, flip angle = 64, SMS = 5, Echo spacing 0.59, 65 interleaved slices with voxel size of 2.4mm x 2.4mm x 2.4mm), each lasting between 4 to 9 minutes, during which they will perform multiple blocks of either the mixed tasks paradigm (Days 2 and 9) or the PRP paradigm (Days 3 and 10).
Study Session Descriptions:
Study Session 1:
During Study session 1, subjects will go through the consenting process with a trained research assistant. After informed consent is provided, subjects will be given an overview of the study and they will be introduced to the basic task procedure and the color, shape and pattern rules. They will practice each task in the single task paradigm for 2 blocks each. Following this they will be introduced to the PRP paradigm with their assigned task orders, for 6 blocks. At the end of the session, subjects will be debriefed and remunerated for their participation.
Study Session 2:
During Study session 2, subjects will undergo baseline measurements with the PRP paradigm with their assigned task orders, for 12 blocks. At the end of the session, subjects will be debriefed and remunerated for their participation.
Study Session 3:
During Study session 3, subjects will undergo baseline measurements with the Mixed tasks paradigm for 12 blocks. At the end of the session, subjects will be debriefed and remunerated for their participation.
Study Session 4:
During Study session 4, subjects will undergo baseline measurements of the neural representations of tasks. The MRI protocol will be administered with the Mixed tasks paradigm.
Study Session 5:
During Study session 5, subjects will undergo baseline measurements of the neural representations of tasks. The MRI protocol will be administered with the PRP paradigm.
Study Sessions 6-8:
Subjects will be administered the treatment during these sessions. The single-task practice treatment group will receive 12-24 blocks of practice with the single task paradigm and they will be provided feedback on their performance after every block along with targets for improvement. The multi-task practice treatment will practice one of the three orders in the PRP paradigm across 12-24 blocks Subjects will be given feedback at the end of each block on their accuracy and speed of responding and they will be given an improvement target.
Study Session 9:
During Study session 9, subjects will undergo endline measurements with the PRP paradigm with their assigned task orders, for 12 blocks. At the end of the session, subjects will be debriefed and remunerated for their participation.
Study Session 10:
During Study session 10, subjects will undergo endline measurements with the Mixed tasks paradigm for 12 blocks. At the end of the session, subjects will be debriefed and remunerated for their participation.
Study Session 11:
During Study session 11, subjects will undergo endline measurements of the neural representations of tasks. The MRI protocol will be administered with the Mixed tasks paradigm.
Study Session 12:
During Study session 12, subjects will undergo endline measurements of the neural representations of tasks. The MRI protocol will be administered with the PRP paradigm.
- Conditions
- Multitasking Behavior and Neural Representations Associated With Multitasking Ability, Healthy Volunteers, Executive Function
- Being tested
- Multitask Practice Intervention (MPI), Single-task Practice Intervention (SPI)
- Keywords
- psychological refractory period (PRP), behavioral training, neural representational geometry, lateral prefrontal cortex, separability and generalizability
- Medical subject headings
- Multitasking Behavior
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Multitask Practice Intervention (MPI)Behavioural
Multitask practice intervention (MPI) includes multiple behavioral testing sessions during which participants receive practice with multitasking two tasks using the psychological refractory period procedure.
Single-task Practice Intervention (SPI)Behavioural
Single task practice intervention (SPI) includes multiple behavioral testing sessions during which participants receive separate practice on two tasks.
| Study group | Role | What they receive |
|---|---|---|
| Multitask Practice | Experimental | Not described Receives: Behavioral: Multitask Practice Intervention (MPI) |
| Single Task Practice | Active comparator | Not described Receives: Behavioral: Single-task Practice Intervention (SPI) |
What is being measured
The primary outcome is the main question the study is designed to answer.
Effect of the practice intervention on change in overall and task-relevant neural separability in lateral prefrontal cortex
Overall neural separability (also referred to as shattering dimensionality) will be measured by employing cross-validated neural decoding of lateral PFC fMRI BOLD multi-voxel patterns, averaging decoding accuracies across all balanced dichotomies of the task inputs. Task-relevant neural separability will be measured by averaging decoding accuracies across all task-relevant variables.
Measured: through study completion, an average of 1.5 years
Effect of multitasking practice on behavioral multitasking cost
Behavioral multitasking cost will be estimated by computing the difference in mean response time on task 2 on long SOAs and short SOAs in the Psychological Refractory Period paradigm. The effect of multitasking practice on behavioral multitasking will be estimated using linear mixed-effects regression, and is defined as the regression weight associated with the interaction effect of time point and intervention on multitasking cost.
Measured: through study completion, an average of 1.5 years
Contribution of overall and task-relevant neural separability in lateral prefrontal cortex to the effect of multitasking practice on behavioral multitasking cost
The contribution of prefrontal neural separability change to the effect of multitasking practice on behavioral multitasking will be estimated using linear mixed-effects regression, and is defined as the regression weight associated with the interaction effect of time point, intervention and separability on multitasking cost.
Measured: through study completion, an average of 1.5 years
Secondary outcomes (2)
Cross-classification generalization performance of task-relevant variables in lateral prefrontal cortex
Cross-classification generalization performance will be estimated by averaging decoding accuracies from cross-classification of individual task variables across subsets of task inputs in the lateral prefrontal cortex.
Measured: through study completion, an average of 1.5 years
Coding axis angles between stimulus feature representations in two tasks in lateral prefrontal cortex
Coding axis angles will be estimated by computing the angle between the weight vectors of linear classifiers trained to decode stimulus features in each task context.
Measured: through study completion, an average of 1.5 years
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted31 May 2024
- Study start27 Mar 2024
- Primary completion31 Jul 2026 (estimated)
- Study completion31 Jul 2026 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for Multitasking Behavior and Neural Representations Associated With Multitasking AbilityStudies of the same condition, open and under way.
- More trials run by Brown UniversityThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 60 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Brown University
- Sponsor type
- University, hospital or other
- Collaborators
- National Institute of Mental Health (NIMH)
- Responsible party
- Sponsor
- Investigators
- David Badre, PhD, Principal investigator, Brown University
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT06436209
- Sponsor's protocol ID
- 0802992441
- Other IDs
- 5R01MH125497
- Status last verified
- May 2025
- First submitted
- 17 Apr 2024
- Last updated
- 15 Aug 2025
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No
- Individual data sharing
- Yes
Study at a glance
From the registry record, last updated by the sponsor on 15 Aug 2025. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Cognitive Control & the Functional Organization of the Frontal Cortex
- ClinicalTrials.gov ID
- NCT06436209
- Acronym / sponsor ID
- 0802992441
- Conditions
- Multitasking Behavior and Neural Representations Associated With Multitasking Ability, Healthy Volunteers, Executive Function
- Keywords
- psychological refractory period (PRP), behavioral training, neural representational geometry, lateral prefrontal cortex, separability and generalizability
- Study type
- Interventional
- Recruitment status
- Recruiting
- Enrolment
- 60 participants (estimated)
- Lead sponsor
- Brown UniversityUniversity, hospital or other
- Collaborators
- National Institute of Mental Health (NIMH)
- Study start
- 27 Mar 2024 (actual)
- Primary completion
- 31 Jul 2026 (estimated)
- Study completion
- 31 Jul 2026 (estimated)
- First posted
- 31 May 2024 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
The goal of this basic experimental clinical trial is to understand the effect of multitasking practice on the structure of neural representations of tasks in the human lateral prefrontal cortex and control brain regions. The main question it aims to answer is: What changes in neural representational structure predict improvements in multitasking behavior due to multitasking practice? Healthy human participants will learn two independent tasks, each mapping a set of stimuli to motor responses based on different rules. Participants will be randomized to one of two interventions. Participants assigned to the multitask practice intervention (MPI) will practice multitasking the two tasks over multiple days. Those assigned to the single-task practice intervention (SPI) will instead practice each task separately while controlling for the total number of practice opportunities associated with each task across the interventions. Both before and after the practice, the ability of all participants to perform both tasks simultaneously will be behaviorally measured using a well-established psychological refractory period (PRP) paradigm, and their neural representations will be measured using functional MRI while they perform the two tasks. Researchers will then compare improvements in multitasking behavior across the two groups, as well as changes in neural representational geometry of the tasks in the lateral prefrontal cortex and control brain regions, and test whether multitasking training is associated with specific changes in neural representations in the lateral prefrontal cortex.
Detailed description
Background and Study Rationale:
Human performance on a task deteriorates when it is performed concurrently with another task. This multitasking cost has been attributed to competition for shared computational or biological resources and there is considerable debate in the field about the specific nature of these putative resources. Extensive multitasking practice is known to reduce, and sometimes, abolish these costs. These practice-related gains have been attributed to changes in central processing, more efficient task scheduling, or the learning of specialized task representations. The human prefrontal cortex is critical to flexible cognitive control of behavior, and is involved in representing tasks. However, it remains unknown what effect multitasking practice has on prefrontal task representations. In this study, we will directly address a gap in our knowledge by testing the link between multitasking costs and the geometry of neural manifolds representing task inputs in the lateral PFC.
Study Design:
Overview:
This study is a single-center, randomized controlled trial designed to examine the effect of multitask practice on multitasking behavior, the geometry of neural representations of tasks in the lateral prefrontal cortex and the relationship between these effects. A total of 60 healthy subjects are planned, 30 subjects being randomized to each, the multitask practice group (MPG), and the single task practice group (SPG). Baseline and endline assessments of multitasking behavior and neural representations in lateral PFC with fMRI will be conducted in all subjects.
Study Treatments:
Single-task practice treatment:
The single-task practice treatment will involve 3 sessions of practice during which subjects will practice instructed tasks in individual task blocks. Up to 48 blocks of practice will be performed. Subjects will be given feedback at the end of each block on their accuracy and speed of responding and they will be given an improvement target.
Multitask practice treatment:
The multitask practice treatment will involve 3 sessions of practice during which subjects will practice instructed tasks in the psychological refractory period paradigm. Up to 48 blocks of practice will be performed. Subjects will be given feedback at the end of each block on their accuracy and speed of responding and they will be given an improvement target.
Subject Selection:
Subjects will be recruited from the Providence community. Subjects will be screened over a phone call. Inclusion criteria include right-handedness, age between 18 and 35, and normal or corrected-to-normal vision. Exclusion criteria include history of psychiatric or neurological deficits and MR contraindications. Consenting procedures will be conducted in person during Study Session 1 and continuing consent will be periodically obtained during all lab Study visits.
Random Assignment:
Up to 60 eligible patients will be randomly assigned to SPG or MPG treatment groups in a 1:1 ratio by using a random number generator coded in MATLAB. Neither the experimenters nor the study subjects, will be blinded to the assignment.
Study Structure:
A total of 14 study sessions are planned for each subject. Study session 1 will be employed for informed consent, scheduling and familiarization with study tasks. Baseline evaluations will take place during study sessions 2 through 5. Treatment will be administered during study sessions 6 through 8 during which subjects will receive either 3 sessions of multi-task practice (MPG) or 3 sessions of single-task practice (SPG). Endline evaluations will take place during study sessions 9 through 12. Detailed descriptions of each Study session and all paradigms used for measurements are given below.
Behavioral paradigms:
All behavioral task paradigms will be implemented using Psychtoolbox 3 in MATLAB or in JSPsych. All tasks involve responding to visual objects presented on a computer screen with keypresses either on a keyboard or on a response box. Visual objects will vary along 4 dimensions - shape (square or circle), circle (orange or blue), pattern (dotted or striped) or size (small or large). Along with the visual object, a response panel consisting of the symbols @ and #. Subjects will be introduced to three different tasks: the shape task, color task and the pattern task. In each task, they will make a binary classification of the visual object relying on the relevant task feature (e.g. color in the color task). Each binary class will be associated with one of two categories associated with the @ and # symbols. Subjects will then select the response key associated with the relevant symbol. The left-right position of the two symbols will be varied randomly from trial to trial such that the position would be the same as the previous trial on approximately 50% of the trials, and each trial-type was associated with an equal number of left and right responses.
Single task paradigm: In the single-task paradigm, visual objects will be presented for up to 2.2 s. Responses deadline is 2.2s. Inter-trial interval will be 1 s. Trials are presented in pure single-task blocks with 64 trials per block.
Mixed tasks paradigm: In the mixed tasks paradigm, visual objects will be presented for up to 2.2 s. Response deadline is 2.2s. Inter-trial interval will be jittered between 2 and 10 seconds. Trials of multiple task types will be presented in the same block, with a word cue identifying the task to be performed on every trial.
Psychological Refractory Period paradigm: In the PRP paradigm, two visual objects will be presented on every trial, one in the upper half of the screen, and the other in the bottom half of the screen. Visual objects will be presented with a stimulus onset synchrony (SOA) varying between 50 ms and 1.5 s. Trial length will be up to 3 s. Response deadline will be 3 s for responding to both visual objects. Inter-trial interval will be either 1 s (behavioral blocks) or jittered between 2 and 10 seconds (MRI blocks). Subjects will be instructed to perform the tasks in a specific order (e.g. Color, then Shape), responding to the first stimulus that appears with the rule associated with the first task in the order and to the object that appears second. A total of 3 different task orders will be presented to subjects (e.g. Color -> Shape, Shape -> Color and Color -> Pattern) and these orders will be counterbalanced across subjects such that each task has placed every role equally in each treatment group. All task orders will be administered during both baseline and endline.
MRI Protocol:
Each subject will under MRI procedures during Study Visits 2, 3, 9 and 10. Each visit will last 2 hrs during which subjects will first be provided refresher instruction on the behavioral tasks before undergoing MRI for 1 hr. During each 1 hr MRI scanning session, subjects will first be screened for metal, briefed on safety procedures and motion minimization requirements, and then situated on the scanning table in a supine position. Their head will be stabilized with soft padding, and their ears will be protected from MR noise with ear plugs. Subjects will view a computer screen through a mirror installed on a headstage and will be provided with two response boxes for performing the tasks and an emergency buzzer for communicating with the experimenters and radiographers on duty. They will then undergo a multiple echo MPRAGE scan (repetition time (TR) = 2530 ms, echo times (TE) = 1.69, 3.55, 5.41, and 7.27 ms, flip angle = 7 degrees, 176 sagittal slices, 1 × 1 × 1 mm voxels) for 6 minutes during which they may close their eyes. Following this, subjects will undergo 5-10 runs of Echo Planar Imaging (TR = 1000 ms, TE = 32.6 ms, flip angle = 64, SMS = 5, Echo spacing 0.59, 65 interleaved slices with voxel size of 2.4mm x 2.4mm x 2.4mm), each lasting between 4 to 9 minutes, during which they will perform multiple blocks of either the mixed tasks paradigm (Days 2 and 9) or the PRP paradigm (Days 3 and 10).
Study Session Descriptions:
Study Session 1:
During Study session 1, subjects will go through the consenting process with a trained research assistant. After informed consent is provided, subjects will be given an overview of the study and they will be introduced to the basic task procedure and the color, shape and pattern rules. They will practice each task in the single task paradigm for 2 blocks each. Following this they will be introduced to the PRP paradigm with their assigned task orders, for 6 blocks. At the end of the session, subjects will be debriefed and remunerated for their participation.
Study Session 2:
During Study session 2, subjects will undergo baseline measurements with the PRP paradigm with their assigned task orders, for 12 blocks. At the end of the session, subjects will be debriefed and remunerated for their participation.
Study Session 3:
During Study session 3, subjects will undergo baseline measurements with the Mixed tasks paradigm for 12 blocks. At the end of the session, subjects will be debriefed and remunerated for their participation.
Study Session 4:
During Study session 4, subjects will undergo baseline measurements of the neural representations of tasks. The MRI protocol will be administered with the Mixed tasks paradigm.
Study Session 5:
During Study session 5, subjects will undergo baseline measurements of the neural representations of tasks. The MRI protocol will be administered with the PRP paradigm.
Study Sessions 6-8:
Subjects will be administered the treatment during these sessions. The single-task practice treatment group will receive 12-24 blocks of practice with the single task paradigm and they will be provided feedback on their performance after every block along with targets for improvement. The multi-task practice treatment will practice one of the three orders in the PRP paradigm across 12-24 blocks Subjects will be given feedback at the end of each block on their accuracy and speed of responding and they will be given an improvement target.
Study Session 9:
During Study session 9, subjects will undergo endline measurements with the PRP paradigm with their assigned task orders, for 12 blocks. At the end of the session, subjects will be debriefed and remunerated for their participation.
Study Session 10:
During Study session 10, subjects will undergo endline measurements with the Mixed tasks paradigm for 12 blocks. At the end of the session, subjects will be debriefed and remunerated for their participation.
Study Session 11:
During Study session 11, subjects will undergo endline measurements of the neural representations of tasks. The MRI protocol will be administered with the Mixed tasks paradigm.
Study Session 12:
During Study session 12, subjects will undergo endline measurements of the neural representations of tasks. The MRI protocol will be administered with the PRP paradigm.
Study design
- Primary purpose
- Basic science
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Multitask Practice | Experimental | Behavioral: Multitask Practice Intervention (MPI) |
| Single Task Practice | Active comparator | Behavioral: Single-task Practice Intervention (SPI) |
Who may qualify
- Ages
- 18 to 35 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (1 listed)
- Normal or corrected to normal vision.
Key exclusion criteria (12 listed)
- Left handedness
- Presence or history of neurological or psychiatric disorders
- Usage of brain related medications
- Previous head injury and time spent unconscious
- Any implanted medial fragment or device in the body of the participant.
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Multitask Practice Intervention (MPI)Multitask practice intervention (MPI) includes multiple behavioral testing sessions during which participants receive practice with multitasking two tasks using the psychological refractory period procedure. | Behavioural | Multitask Practice |
| Single-task Practice Intervention (SPI)Single task practice intervention (SPI) includes multiple behavioral testing sessions during which participants receive separate practice on two tasks. | Behavioural | Single Task Practice |
Primary outcome
Effect of the practice intervention on change in overall and task-relevant neural separability in lateral prefrontal cortex
Time frame: through study completion, an average of 1.5 years
Overall neural separability (also referred to as shattering dimensionality) will be measured by employing cross-validated neural decoding of lateral PFC fMRI BOLD multi-voxel patterns, averaging decoding accuracies across all balanced dichotomies of the task inputs. Task-relevant neural separability will be measured by averaging decoding accuracies across all task-relevant variables.
Effect of multitasking practice on behavioral multitasking cost
Time frame: through study completion, an average of 1.5 years
Behavioral multitasking cost will be estimated by computing the difference in mean response time on task 2 on long SOAs and short SOAs in the Psychological Refractory Period paradigm. The effect of multitasking practice on behavioral multitasking will be estimated using linear mixed-effects regression, and is defined as the regression weight associated with the interaction effect of time point and intervention on multitasking cost.
Contribution of overall and task-relevant neural separability in lateral prefrontal cortex to the effect of multitasking practice on behavioral multitasking cost
Time frame: through study completion, an average of 1.5 years
The contribution of prefrontal neural separability change to the effect of multitasking practice on behavioral multitasking will be estimated using linear mixed-effects regression, and is defined as the regression weight associated with the interaction effect of time point, intervention and separability on multitasking cost.
2 secondary outcomes
Cross-classification generalization performance of task-relevant variables in lateral prefrontal cortex
Time frame: through study completion, an average of 1.5 years
Coding axis angles between stimulus feature representations in two tasks in lateral prefrontal cortex
Time frame: through study completion, an average of 1.5 years
Results and safety
This study is still under way. Results are not available in the source record yet.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 15 Aug 2025.
- Individual participant dataSharing planned: Yes
Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.
David Badre, PhD principal investigator
Brown University
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Multitask Practice Intervention (MPI) and Single-task Practice Intervention (SPI) in people with Multitasking Behavior and Neural Representations Associated With Multitasking Ability and Healthy Volunteers, run by Brown University at 1 site in United States.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 12 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: looking for participants now, as of the sponsor's last update on 15 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in United States. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
This study is still under way. Results are not available in the source record yet.
How can a doctor refer a patient or contact the research team?
Contact David Badre, PhD (401-863-9563, david_badre@brown.edu), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Effect of the practice intervention on change in overall and task-relevant neural separability in lateral prefrontal cortex (time frame: through study completion, an average of 1.5 years). The study lists 3 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 15 Aug 2025.