Systematic Psychophysical

NCT ID: NCT06965478

Last Updated: 2025-11-19

Basic Information

• Recruitment Status: RECRUITING
• Clinical Phase: NA
• Total Enrollment: 400 participants
• Study Classification: INTERVENTIONAL
• Study Start Date: 2025-07-22
• Study Completion Date: 2029-01-31

Brief Summary

The purpose of this study is to investigate how our performance changes after our perceptual system is trained in a certain way ("perceptual learning"). In addition, investigators are interested in identifying and characterizing relationships between such changes and neuroimaging signals recorded from the human brain.

Detailed Description

The long-term goal of the proposed project is to elucidate the underlying mechanisms of visual perceptual learning (VPL) for artificial and natural stimuli, which will be instrumental in developing rehabilitation programs aimed at enhancing damaged or deteriorating vision. The specificity of VPL to the feature and location of the trained visual stimulus is a fundamental characteristic of VPL. To investigate the specificity, one effective way is to use an artificial stimulus such as a Gabor patch as the trained stimulus, as it has been widely used to investigate basic visual processing. Simultaneously, to create an impactful rehabilitation program, the resulting improvements must be generalized to untrained features and locations in visual stimuli encountered in everyday life, including natural scenes (NS). However, it remains uncertain whether the same mechanisms underlie the generalization and specificity in VPL for artificial and NS stimuli. In Specific Aim (SA) 1, investigators aim to examine basic mechanism of the specificity using a Gabor patch. According to a prevailing theory, early visual processing (e.g., 0 to 150ms after the stimulus onset) primarily involves input-level feedforward signals. In contrast, late processing (e.g.,150-300ms after the stimulus onset) involves recurrent processing. To better understand the mechanism of the specificity of VPL it is crucial to clarify whether early or late processing is involved. Additionally, it remains unclear whether the specificity of VPL involves excitation on the trained feature and location or inhibition on untrained features and locations. Therefore, investigators will test Hypothesis 1 (H1): Late processing (H1-a) or early processing (H1-b) plays a role in the specificity of VPL, and H2: Excitatory signals (H2-a) or inhibitory signals (H2-b) are involved in inducing the specificity of VPL. investigators will employ two methods. The backward masking (BM) is used to disrupts and reveal roles of late processing. In preliminary results, BM applied to the trained orientation eliminated the orientation specificity in VPL, supporting H1-a. A Rhythmic Synchronization Orientation Decoding Change (RSDC) method is a novel method that examines at which band(s) of rhythmic synchronization from electroencephalogram (EEG) the decoding performances of trained and untrained features and locations change after VPL training. Preliminary results suggest that trained orientation signals are enhanced at both trained and untrained locations during early processing, while those at untrained locations are inhibited during late processing, leading to the location specificity. In SA2, investigators will examine the specificity and generalizability of VPL for NS. Our first step is to test H3: VPL for the dominant orientation in NS is specific (H3-a) or generalized (H3-b) to other orientations. Preliminary results support H3-b. If true, investigators will further investigate the aspects in NS that induce the generalization of VPL. Preliminary result suggests that higher-order statistics, involving correlations between different orientation and spatial frequency channels derived from NS, play a role in the generalization of VPL for NS. Investigators further aim to test H1 and H2 for NS images, using both the BM and RSDC methods.

Conditions

Perceptual Learning

Study Design

• Allocation Method: NA
• Intervention Model: PARALLEL
• Primary Study Purpose: BASIC_SCIENCE
• Blinding Strategy: SINGLE

Interventions

Visual Training

Participants are asked to detect or discriminate visual stimuli.

Intervention Type: BEHAVIORAL

Eligibility Criteria

Inclusion Criteria

• Ages 18 - 60,
• Normal or corrected-to-normal vision

Exclusion Criteria

• Eye disorders (cataracts, age related macular degeneration, diabetic retinopathy, glaucoma)
• Drug use (psychoactive drugs, neuroleptic medications, prescription medications that might affect cognitive and motor performance)
• Sleep disorders (sleep apnea, insomnia)
• Magnetically or mechanically activated implants (such as cardiac pacemakers)
• clips on blood vessels in the brain
• intrauterine devices
• dentures
• pregnancy

• Minimum Eligible Age: 18 Years
• Maximum Eligible Age: 60 Years
• Eligible Sex: ALL
• Accepts Healthy Volunteers: No

Sponsors

National Eye Institute (NEI)

NIH

Sponsor Role: collaborator

Brown University

OTHER

Sponsor Role: lead

Responsible Party

Takeo Watanabe

Fred M. Seed Professor

Responsibility Role: PRINCIPAL_INVESTIGATOR

Locations

Brown University

Providence, Rhode Island, United States

Site Status: RECRUITING

Countries

United States

Central Contacts

Takeo Watanabe

Role: CONTACT

takeo_watanabe@brown.edu

401-863-6916

Research Assistant

Role: CONTACT

akiko_norton@brown.edu

401-863-5186

Facility Contacts

Academic Department Manager

Role: primary

reinette_sousa@brown.edu

401-863-2702

Other Identifiers

R01EY019466

Identifier Type: NIH

Identifier Source: secondary_id

View Link

1203000582-02

Identifier Type: -

Identifier Source: org_study_id