Moderators and Mediators of Perceptual Learning

Cognitive Change Clinical Trial

Official title:

Moderators and Mediators of Perceptual Learning

Clinical Trial Details — Status: Recruiting

Administrative data

• NCT number: NCT05894967
• Other study ID #: 2020-0138
• Secondary ID: R01EY031226L&S/P
• Status: Recruiting
• Phase: N/A
• Start date: April 14, 2023
• Est. completion date: March 31, 2027

Study information

• Verified date: June 2024
• Source: University of Wisconsin, Madison
• Contact: Audrey A Carrillo, MA
• Phone: 6264828091
• Email: audreyc[@]ucr.edu
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial Summary

This study addresses the fundamental issue of specificity and generality of training in the context of Perceptual Learning (PL). PL broadly encompasses the set of mechanisms through which experience with the environment gives rise to changes in perceptual processing. Careful research in this domain can greatly enhance our basic understanding of the perceptual systems and the plasticity of these systems. Furthermore, translational approaches underpinned by the basic science of PL are becoming increasingly prominent. This includes a host of emerging translational approaches for the rehabilitation of both perceptual deficits and for cognitive training, which are believed to share cortical plasticity mechanisms. However, while existing research provides evidence that PL approaches can improve perceptual skills, our ability to develop effective interventions is limited by a lack of understanding of the behavioral outcomes associated with different PL approaches. One major obstacle to successful translation of PL is that the field to-date has been strongly driven by "novel" and "provocative" findings demonstrated via small N studies with very few projects digging deep to achieve robust and reliable results. In turn, not surprisingly, the field of PL, like many others in psychology, has suffered from numerous replication challenges. Here we address these limitations by comparing a large number of different training tasks using common outcome measures and in a large subject population. Each training tasks involves a different "critical feature" for learning proposed by one or more research groups. However, these training tasks have never been directly compared or contrasted. Robust and reliable results will be achieved by training a large sample of participants on PL tasks and assess the outcomes via a common set of measures. The investigators will also collect a broad assessment of individual differences, which will provide a unique dataset that can resolve controversies in the literature and lead to new understandings. Our proposed analytical approach tests several key hypotheses in the field, explores the extent to which different training approaches lead to systematically different profiles of learning, and examines how these can differ based upon the individuals being trained.

Description:

The present study investigates the mechanisms of Perceptual Learning (PL), with a focus on training task characteristics that induce generalizable enhancements in visual performance (i.e., that produce benefits on tasks beyond just the trained task, as this is critical for training to have translational value). To achieve this, we target PL of spatial vision in human subjects, which is the most common target of PL in basic science research.

The investigators run a large number of participants across 12 separate conditions thought to mediate effects of PL (e.g., training with flanking stimuli, use of noise, manipulating difficulty during training, multisensory facilitation with sound, training with a diversity of stimuli, and cueing attention during training) using common outcome measures, and analyze both the effect of training condition and individual differences that impact learning. A novel crossover design is used to train participants sequentially on two tasks and examine learning and generalization to determine which methods involve redundant or independent processes. It is noted that the first phase of training is the primary clinical trial and that the crossover is to address a mechanistic question regarding interactions of different training types. It is hypothesized that training with mostly difficult, precise stimuli will give rise to less generalization than training with easy, imprecise stimuli after sequential double training.

The investigators also specifically examine biological variables, such as sex and age, in addition to personality traits, sleep habits, motivation, and individual differences in baseline performance to gain a more complete understanding of how these factors may moderate outcomes of PL (including generalization to more real-world contexts, such as reading). It is hypothesized that a number of individual differences, both cognitive and personality based, will predict PL outcomes.

Recruitment information / eligibility

• Status: Recruiting
• Enrollment: 1140
• Est. completion date: March 31, 2027
• Est. primary completion date: February 28, 2027
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: All
• Age group: 18 Years to 30 Years

Eligibility

Inclusion Criteria:

• 18 and 30 years of age

• Corrected vision of 20/40 or better (as assessed with an eye chart)

• No reported incidence of retinal pathology or neurological disease

Exclusion Criteria:

• Corrected vision of 20/40 or worse

• Evidence of retinal pathology or retinal disease

Related Conditions & MeSH terms

• Cognitive Change

Intervention

Behavioral:
• C1 - Standard Perceptual Learning (SPL)
Each trial starts with a fixation point (500ms) after which a Gabor (1° radius, at cut-off SF of 25% accuracy, estimated from Pre-Test CSF, at either 45° or 135°) appears for 128ms. The task is to indicate whether the Gabor was tilted left or right. Gabor contrast will be controlled by a 3/1 staircase (converging on approximately ~80% contrast threshold) across all training sessions.
• C2 - Long Training (LT)
Will be the same as the SPL with the exception that each session in LT will be twice as long as in SPL.
• C3 - Short Staircases (SS)
Will be largely the same as SPL with the only difference being a change to the adaptive procedure. SS will use so-called "short-staircases," which are initialized at 60% contrast with steps of .05 log units and employs a 3/1 staircase that after every 40 trials is reset (the "short" in "short-staircases") back to 60% contrast.
• C4 - Mixed Difficulty (MD)
This condition will be identical to SPL with the exception that two staircases - one a 2/1 staircase producing difficulties centered around 60-70% accuracy, the other a 4/1 staircase producing difficulties centered around 85-95% accuracy - will be utilized to control the stimuli.
• C5 - Noise Training (NT)
The NT condition will be the same as SPL with the exception that contrast thresholds will be estimated in 5-different levels of external noise (10%, 15%, 20%, 25%, 30%).
• C6 - Training with Flankers (TWF)
TWF will be reasonably different from the standard SPL task. Here, on 50% of trials a target Gabor will be presented at either 45° or 135° (as in SPL) and will be flanked by two collinear Gabors. On the remaining 50% of trials, flankers will be present without a target. TWF is thus a yes/no detection task, which is necessary since the collinear flankers fully indicate the target orientation. In different 20-trial mini-blocks the flankers will appear either lambda, 1.5 lambda, or 2 lambda from the target (i.e., closer or further from the target) and target contrast will be controlled by a 3/1 staircase separately for each spacing.
• C7 - Parafoveal Training (PT)
The PT condition is the baseline for C8-C11 (all of which involve parafoveally presented targets). In PT, we utilize the same task as in SPL, however, in PT, in addition to central training, targets will also appear in one of two peripheral locations (5° eccentricity; angles = 135° and 270°). The location of targets will be randomized trial-wise so as to discourage eye-movements and independent 3/1 staircases will be run at each location. By training only 2 peripheral locations we can measure the extent to which training gives rise to location transfer (e.g., in transfer tasks examining performance at 8 different locations - 2 trained locations and 6 untrained locations). Furthermore, training at the central location facilitates comparisons between PT and SPL.
• C8 - Stimulus Variety (SV)
The base task for SV is the PT condition. However, SV employ 20 trial mini-blocks of different SFs (.75, 1.5, 3, 6, 12, 24 cpd) and locations (45°, 135°, 225°, 315° - i.e., more locations than PT, but not the full set tested in the transfer battery) with separate staircases for each SF and location. Orientations will also be drawn from a larger set (22.5°, 45°, 67.5° - for which participants respond "clockwise" and 112.5°, 135°, 157.5° - for which participants respond "counter-clockwise") and will vary on a trial-by-trial basis. This design holds-out 4 locations and 2 orientations to address transfer.
• C8a - Complex Features (CF)
This is the same as C8, however we will use band-pass filtered stimuli similar to what has been done by a number of groups including Hussein et al.
• C9 - Exogenous Attention Training (ExAT)
Stimuli will be presented in a similar manner as in PT. However, in ExAT, a 100% valid cue, a small black dot - 48ms duration with an 96ms SOA prior to stimulus onset - will appear above the target location on each trial.
• C10 - Endogenous Attention Training (EnAT)
Stimuli will be presented in a similar manner as in PT. However, in EnAT, a 100% valid cue (letter UL, LR; standing for upper left and lower right, respectively) - 150ms duration with an 500ms SOA prior to stimulus onset - will appear at the fixation point.
• C11 - Multisensory Facilitation (MF)
MF utilizes the same basic task structure as in ExEAT, however, rather than a visual cue, an auditory cue will be used (50ms, 1000hz tone with sound location determined by convolving sound with generic head-related transfer function, kemar large ears.
• No Contact Control
While not a "training condition" one type of experience that could be part of a condition is a no contact control (i.e., where participants do no training activities over the same rough time span as for the other training tasks).

Locations

Country	Name	City	State
United States	Northeastern University	Boston	Massachusetts
United States	University of Wisconsin	Madison	Wisconsin
United States	University of California	Riverside	California

Sponsors (2)

Lead Sponsor	Collaborator
University of Wisconsin, Madison	National Eye Institute (NEI)

Country where clinical trial is conducted

United States, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Change in Near Transfer Task	We will utilize an overarching task structure that allows us to assess learning on trained stimuli and transfer to untrained stimuli; locations, orientations, stimulus timings (e.g., we will assess contrast sensitivity for 6 different orientations). A trial begins with a fixation-point presented for 500ms. A target stimulus then appears for 128ms and then disappears (this timing was chosen to preclude participants making eye-movements to the stimuli). The participant is then required to respond by indicating the orientation of the stimulus (e.g., the major axis of a Gabor stimulus or gap-side of a C stimulus). In contrast tests, a staircase is run on the contrast of the target stimulus. In acuity tests, a staircase is run on the size of the stimulus. In parafoveal tests, stimuli are presented at 5° eccentricity.	Baseline to Post-test 2, an average of 5-8 weeks
Primary	Change in Transfer to Visual Search	In a T/L annular visual-search task (1° stimuli, presented at 5° eccentricity at each of 8 evenly spaced locations), on each trial, 7 positions are filled with a distractor (upside-down Ls, half black and half white), while 1 position contains a target (rightside-up T that is either white or black). Stimuli are presented for 256ms and, after a variable SOA, a stimulus-mask (asterixis) appears. Participants report the color of the T. A 3/1 staircase controls the SOA of the mask (shorter SOAs = less time between stimulus and mask = more difficult). This task tests how training impacts processing time (i.e., time necessary to find and identify targets). Also, given that the same locations are used as in the parafoveal training, we can also estimate the extent to which transfer to visual search occurs and, if so, whether it is specific to the trained location.	Baseline to Post-test 2, an average of 5-8 weeks
Primary	Change in Transfer to Reading	To understand visual performance related to reading, we employ the MNRead task, where participants read short sentences out-loud at various font-sizes. Dependent variables include reading speed, minimal text-size (another measure of acuity), and also critical print-size (text-size at which reading speed slows down).	Baseline to Post-test 2, an average of 5-8 weeks
Primary	Change in Transfer to Auditory Attention	The procedure is based upon a speaker-on-speaker task where participants choose between 36 call signs (a color and number) spoken by a speaker. This task measures auditory thresholds for speech in the presence of other talkers, when all talkers are spatially collocated compared to when they are spatially offset.	Baseline to Post-test 2, an average of 5-8 weeks