Methods to Test Visual Attention Online

The overall goal of this procedure is to simplify data collection for visual attention tasks via an online web application. This is accomplished by first logging in participants to a web application. Next, the participants are instructed to calibrate their screens for correct stimulus presentation.

Then the participants read the task instructions and complete practice trials. Finally, data is collected from participants as they complete the full tasks. Ultimately, online data collection methods for visual tasks show consistent results with that of traditional lab-based methods.

The main advantage of this technique over existing methods is that data can be collected from a larger, more diverse population in a relatively short amount of time. Demonstrating this procedure will be Olga P equal, a technician in the lab. To begin, have the participant sit in a quiet room free of distractions with an internet enabled computer at a comfortable height.

Instruct the participant to navigate to the web application shown here. Using an HTML five compatible browser, have the participant input a unique ID that will be associated with the data collected and stored in a my SQL database. Before logging in, obtain consent from the participant via a consent form linked on the page.

To calibrate the screen, ask the participant to input the diagonal size of the screen in inches in the labeled text box. If the participant doesn't know this information, have them find a CD or credit card as a calibration object. When one is selected, prompt the participant to place the object against the screen and align it with a representative image of the object displayed on the screen.

Prompt the participant to adjust the size of the screen image to match the size of the physical object based on the measurements of the physical CD or a credit card and the pixel size of the representative image. Determine the diagonal size of the screen in inches. Have the participant confirm this value through a dialogue box.

Next, prompt the participant to adjust the screen brightness settings until all 12 bands in a black to white gradient displayed on the screen are clearly distinguishable. Ask the participant to sit in arm's length away from the monitor in a comfortable position and then set the browser window to full screen mode. The browser window must be in full screen mode to maximize the visual space used by the tasks and to remove any visual distractions such as the browser toolbar and desktop task bars.

Using the self-guided multiple object tracking or MOT tutorial found at this URL, ask the participant to read the step-by-step instructions that demonstrate how the trials will work. Once the participant finishes reading the instructions, prompt the participant to go through the practice trials, set up the practice stimuli to consist of eight dots at 0.8 degrees with a movement speed of two degrees per second. Use the HTML five request animation frame API to optimize browser animation at a frame rate of 60 hertz in order to control this stimulus motion.

Next, prompt the participant to track the blue dots with the yellow dots acting as distractors. After two seconds, change the blue dots to yellow dots and continue to move them amongst the original yellow dots for another four seconds. At the end of each trial, stop the dots and highlight one.

Prompt the participant to respond via key press, whether the highlighted dot was a track dot or a distractor dot. After three consecutive correct trials or a maximum of six trials, move the participant onto the full task. To start the full MOT task for the participant, set it up with 16 dots that move at five degrees per second.

Within the space between two degrees eccentricity and 10 degrees eccentricity, have the participant complete a total of 45 trials, A mixture of five trials consisting of one tracked dot and 10 trials each consisting of two to five tracked dots. Using the tutorial found here, ask the participant to go through four stages of step-by-step instructions that demonstrate the two target stimuli that must be attended to during the useful field of view or UFOV task set. The central target stimulus is a one degree smiley that flashes at the center of the screen with either long or short hair.

Randomize the smiley's hair length across trials, set the peripheral target stimulus as a one degree star that flashes at four degrees eccentricity at one of eight locations around the circle. Randomize the location of the star across trials. For stage one only.

Display the central target and then prompt the participant to respond via a key press, which hair length was displayed for stage two only. Display the peripheral target and then prompt the participant to click on one of eight radio lines representing the eight possible target locations to indicate where the star appeared. For stage three, display both central and peripheral target stimuli and then prompt the participant to provide responses to both the type of smiley and the location of the star.

For stage four, display both target stimuli in addition to peripheral distractors and then prompt the participant to respond to both target stimuli. For the distractors display, one degree squares presented at the remaining seven locations at four degrees eccentricity in addition to eight more squares at two degrees eccentricity. After the participant's response, show the participant feedback for each target response After each trial, after getting three consecutive correct trials, move the participant onto the next practice stage.

After stage four, prompt the participant to start the full UFOV task. Present the same central stimulus as in the practice session. Display the peripheral target at seven degrees eccentricity at one of the previously mentioned eight locations.

24 distractors squares are also displayed at three degrees eccentricity, five degrees eccentricity, and the remaining seven degrees centricity locations. Use a three down one-up staircase procedure to determine the presentation time of the stimuli decrease the duration of stimuli after three consecutive correct trials and increase after each error trial and the task. When one of three conditions is met, the staircase procedure reaches eight reversals.

The participant completes 10 consecutive trials at either the ceiling duration of 99 frames or floor duration one frame, or the participant reaches a maximum of 72 trials. Data from 1, 744 online participants were used for MOT analysis. MOT performance was measured by calculating the mean accuracy for each set.

Size accuracy range from 0.4 to 1.0 for set size one to 0.1 to 1.0 for set size five and mean accuracy ranged from 0.99 for set size one to 0.71 for set size five. The median accuracy scores ranged from 1.0 to 0.70 for set size one and five respectively. Accuracy decreased as set size increased demonstrating a typical MOT effect for the UFOV task.

Data from 1, 747 online participants were analyzed. Performance was calculated by averaging the presentation time over the final five trials in order to obtain a detection threshold, which reflects the minimum presentation duration at which the participants can detect the peripheral target with approximately 79%accuracy. The mean UFOV threshold was 64.7 milliseconds and scores range from 17 milliseconds to 315 milliseconds with a median threshold of 45 milliseconds.

The threshold distribution was positively skewed with skewness of 1.92 and kurtosis of 3.93. Results were consistent with previous work. After watching this video, you should have a good understanding of how to develop multiple object tracking and useful field of view experiments as web applications following this procedure.

Other methods with precise visual stimulus presentation could also be adapted for an online environment. Data could then be collected from a more generally representative population or from a specific subtype of individuals who are difficult to bring into the lab. Thanks for watching.