Mixed Vs Blocked Search: Four Unique Tasks

NCT ID: NCT06933693

Last Updated: 2025-04-21

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: NA
• Total Enrollment: 40 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2024-06-01
• Study Completion Date: 2029-06-30

Brief Summary

The goal is to look for qualitative differences in visual search behavior when one search is performed many times in a row compared to when multiple search tasks are intermixed. Four search tasks are tested. In the Mixed condition, the four tasks are randomly changed from trial to trial. In the Blocked condition, each task is run as a block of 100 trials.

Detailed Description

NOTE: This registration is linked to a Human Subjects registration in ASSIST. That, in turn, is part of an NCI Grant, R01EY017001. The grant describes many proposed experiments and notes that many others might be done as follow-up studies. At the suggestion of the NIH, the investigators grouped these studies into several "studies", each covering multiple experiments. The experiment described here is part of Aim 1 of R01EY017001. It is not possible to register a set of experiments through the PRS system in CT.gov and it is not possible to file an annual report for the grant (RPPR) without an NCT number for projects that have started collecting participants. Accordingly, the investigators are describing one experiment here that would be part of the "Project 1" bundle of studies.

When scientists study visual search in the lab, they usually ask people to do dozens of instances of the same type of task in a block. (e.g., Please find a vertical line….in the next 100 trials). However, in many (maybe most) visual searches in the real world, the participants are rarely looking for the same item (or same type of item) back-to-back. You do one search. Then the participants do another, and so on. (Find the jam. Now, find the bread. Now find a knife, etc). We want to know if the investigators would get the same results if the investigators mixed different searches together as the investigators do when the investigators test in long blocks of one specific type of search. This is important because the investigators want to know if the rules, established by years of blocked experiments, continue to apply in the more mixed real world.

There are multiple variants of this mixed/block experiment. In Experiment 1, observers are trained on four different search tasks. Then they perform 400 trials in the Mixed condition and the Blocked condition. In the Mixed condition, the four tasks are randomly changed from trial to trial. In the Blocked condition, each task is run as a block of 100 trials. Stimuli are placed in random locations in a jiggled 5 x 5 grid. The grid are placed within square field that is 0.5 of the maximum height of the screen. Each stimulus item fit into an invisible box that is 0.11 of the screen height. If the viewing distance is about 60 cm, a standard computer screen would show a stimulus field of about 15 deg on a side and each item would be placed in a box of about 3 x 3 deg. The background is white. Trials are divided evenly between three set sizes: 8, 16, and 24 items and evenly between target-present and absent trials. Stimuli are presented until the observer responds by pressing either 'p' or 'q' to indicate target present or absent, respectively. Accuracy feedback is provided after each trial.

Conditions

Vision; Healthy; Attention

Study Design

• Allocation Method: RANDOMIZED
• Intervention Model: SEQUENTIAL
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: NONE

Study Groups

Blocked Trials

There are four search tasks in this experiment. Each task will be presented in a separate block of 100 trials

Group Type: EXPERIMENTAL

Blocked Trials

Intervention Type: BEHAVIORAL

Each search task will be presented in a block of trials.

Mixed Trials

There are four search tasks in this experiment. All tasks will be randomly mixed in a single block of 400 trials.

Group Type: EXPERIMENTAL

Mixed trials

Intervention Type: BEHAVIORAL

All tasks will be randomly mixed in a single block of 400 trials.

Interventions

Mixed trials

All tasks will be randomly mixed in a single block of 400 trials.

Intervention Type: BEHAVIORAL

Blocked Trials

Each search task will be presented in a block of trials.

Intervention Type: BEHAVIORAL

Eligibility Criteria

Inclusion Criteria

• Pass Ishihara color vision test

Exclusion Criteria

• vision less than 20/25 with correction
• history of neuromuscular or visual disorders

• Minimum Eligible Age: 18 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: Yes

Sponsors

National Eye Institute (NEI)

NIH

Sponsor Role: collaborator

Brigham and Women's Hospital

OTHER

Sponsor Role: lead

Responsible Party

Jeremy M Wolfe, PhD

Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Principal Investigators

Jeremy M Wolfe, PhD

Role: PRINCIPAL_INVESTIGATOR

Brigham and Women's Hospital

Locations

Brigham & Women's Hospital

Boston, Massachusetts, United States

Site Status: RECRUITING

Countries

United States

Central Contacts

Jeremy M Wolfe, PhD

Role: CONTACT

jwolfe@bwh.harvard.edu

6178511166

Cailey Tennyson, BA

Role: CONTACT

ctennyson1@bwh.harvard.edu

617-525-3681

Facility Contacts

Cailey Tennyson, BA

Role: primary

ctennyson1@bwh.harvard.edu

617-525-3681

Jeremy M Wolfe, PhD

Role: backup

jwolfe@bwh.harvard.edu

617-851-1166

Other Identifiers

R01EY017001

Identifier Type: NIH

Identifier Source: secondary_id

View Link

2007P000646-G

Identifier Type: -

Identifier Source: org_study_id