Levari Exp.20: 2D - Partial Feedback

Project 2: Levari Exp.20: 2D - Partial Feedback NOTE: Note, This is One of Many Studies Under Project 2 in the Original Grant

Suppose that observers are trying to classify a spot on the skin as normal or abnormal and suppose that the two attributes that are important are the color and shape of the spot. The investigators have found that perceptual decisions of this short are shaped by the prevalence of the target abnormality and by the feedback that observers (Os) receive. If abnormal spots are rare (low prevalence), Os will tend to become more conservative about calling spots abnormal. In this experiment, Os see items defined by color and shape. They are looking for one combination (bumpy green). Bumpy green targets can be common (50% prevalence) or rare (10%). Os in one group will get feedback about their responses based on color. The other group will receive feedback based on shape. The investigators will look for effects of prevalence and of the type of feedback. The goal is to better understand perceptual decisions in settings like clinical evaluation of skin lesions.

Study Overview

• Status: Completed
• Conditions: Decision Making; Form Perception; Color Perception
• Intervention / Treatment: Behavioral: Color Feedback; Behavioral: Shape Feedback

Detailed Description

Suppose that observers are trying to classify a spot on the skin as normal or abnormal and suppose that the two attributes that are important are the color and shape of the spot. The investigators have found that perceptual decisions of this short are shaped by the prevalence of the target abnormality and by the feedback that observers (Os) receive. If abnormal spots are rare (low prevalence), Os will tend to become more conservative about calling spots abnormal.

In this experiment, Os see items defined by color and shape. Items vary in dominant color from purple to green. Items vary in shape from relatively smooth irregular blobs (nicknamed "Bouba") to relatively bumpy blobs (nicknamed "Kiki"). Os are asked to find "Green Kikis". Since color and shape vary continuously, the border between Green Kiki and not Green Kiki will not be clear to the Os. Os will be asked to label each item as Green Kiki or not. Saying "maybe" is not an option.

The between-subject variable is the type of feedback Os receive. One set of Os will get feedback about color. That is, if the observer says "yes, this is a green kiki", they will be told only "Yes, this was a green item" or "no this was not green". The other group will get shape feedback: e.g. "Yes, this was a Kiki.".

The within-subjects variable is the target prevalence. The investigators can divide the stimuli into four quadrants: Green Kiki targets, and Green Bouba, Purple Bouba, and Purple Kiki distractors. In the high prevalence trials, 50% of the stimuli will be drawn from target quadrant (green kiki) and 17% from each of the remaining three quadrants. In the low prevalence trials, 10% of the stimuli will be drawn from the target quadrant while 30% will be drawn from each of the other three quadrants. The whole space of stimuli has 10 shape values and 10 color values for a total of 100 possible types of stimulus.

The key dependent is the proportion of target-present responses for each type of stimulus.

To analyze the data, the investigators will create a heatmap showing the percentage of times Os judge each of the 100 categories (10 colors X 10 shapes) as the target, separately for the high prevalence and low prevalence block. The investigators will calculate the response difference between the two blocks within subjects and will calculate the difference between shape and color feedback between observers.

Observers with an average accuracy below 70% will be excluded. Prior experiments have a conservative effect size of ~0.8 for differences between high and low prevalence. Some effects in experiments proposed here may have more subtle effects so power will be calculated based on an effect size of 0.6. To detect such a difference between, for instance, the 50% points on two functions like those in the data figures above, requires 26 observers to achieve alpha of 0.05 and power of 0.9. The investigators will aim for 26 observers in each condition.

• Study Type: Interventional
• Enrollment (Actual): 55
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Massachusetts
    • Boston, Massachusetts, United States, 02215
      • Visual Attention Lab / Brigham and Women's Hospital

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

normal color vision- 20/25 or better acuity

Exclusion Criteria:

no history of visual or oculomotor disease-

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Single

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Color Feedback; Observers are told if the color but not if the shape was correctly identified	Behavioral: Color Feedback; Feedback is given about the correctness of the response on the color dimension
Experimental: Shape Feedback; Observers are told if the shape but not if the color was correctly identified	Behavioral: Shape Feedback; Feedback is given about the correctness of the response on the shape dimension

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Percentage of stimuli identified as target items	Participants are presented with visual stimuli from a 10 by 10 set of 100 possibilities. There are 10 levels of color (blue to green) and 10 levels of shape (smooth="Bouba" to bumpy = "Kiki", fully crossed with each other. Participants are asked to state whether an item is or is not a "green Kiki" target. For each of the 100 items, the primary outcome measure is the percentage of time that the specific item is called "Green Kiki" target.	Through study completion, an average one 1 year

Collaborators and Investigators

• Sponsor: Brigham and Women's Hospital
• Investigators: Principal Investigator: Jeremy M Wolfe, PhD, Brigham and Women's Hospital

Study record dates

Study Major Dates

• Study Start (Actual): May 1, 2021
• Primary Completion (Actual): June 1, 2021
• Study Completion (Actual): June 1, 2021

Study Registration Dates

• First Submitted: March 27, 2024
• First Submitted That Met QC Criteria: April 2, 2024
• First Posted (Actual): April 10, 2024

Study Record Updates

• Last Update Posted (Actual): August 13, 2024
• Last Update Submitted That Met QC Criteria: August 10, 2024
• Last Verified: August 1, 2024

More Information

Terms related to this study

• Keywords: feedback; decision making; prevalence effects; shape perception
• Other Study ID Numbers: 2007p000646-F

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: de-identified data will be posted on the Open Science Framework site
• IPD Sharing Time Frame: available after data collection, no end time
• IPD Sharing Access Criteria: openly available
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ICF

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No