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What do you see in the Ganzflicker?

A visual flicker is known to induce "Ganzfeld imagery" (Allefeld et al., 2011; Sumich et al., 2018), a type of visual pseudo-hallucination. The continuous flicker facilitates visual imagery, but does not induce any permanent changes in the brain and does not elicit actual hallucinations. For best results, view the Ganzflicker in a dark room, on a desktop/laptop rather than mobile, and listen to the music over headphones.


Click on the picture to go straight to the video. This plays 10 minutes of Ganzflicker with music

Or click on the button to go to the questionnaire

Please fill out a short questionnaire

Whether you saw something or not, I would like to hear from you! Please fill out the questionnaire after you try the Ganzflicker. Your responses will contribute to our growing understanding of individual differences in mental representations and their influence on perception. The questionnaire takes about 10 minutes and can be found in the video description or by clicking the button above.

Imagery priming

Can a priming task measure your imagery vividness?

You may be familiar with the classic "Stroop" phenomenon, where you are presented with a rapid succession of color words (e.g., RED, GREEN, BLUE). The word can appear in a congruent font color or another color, and you are asked to either read the word aloud, or say the colour of the font. Even if the word RED is shown in blue font, it is easy to say the word aloud. But because reading is such an automatic process, it is difficult to switch to saying the color of the font instead of reading the word. The word therefore interferes with your ability to say the color of the font out loud. The current task is an adapted version of the classic Stroop task, where you are tested on your ability to respond quickly to the word that is shown.

I am interested to test your ability to ignore background colors while performing a word identification task. Here you will be asked to identify color words that appear for 32 milliseconds, preceded briefly by a change in background color that may or may not correspond to the word. A previous study (Cui et al., 2008) found that people are faster to respond to a word with a congruent background color, and this effect is correlated with imagery vividness (more vivid imagery = stronger congruency effect). I am interested to test this effect in people with different imagery vividness, to determine whether there is a simple behavioral task that can identify aphantasia.

Memory formats

How do you remember sensory information?

In what format do different people represent sensory information? Many studies have shown that people can simulate sensory processing in the absence of a sensory stimulus (Harrison & Tong, 2009; Udale et al., 2018), but other experiments have demonstrated that sensory information can be translated into a completely non-sensory format (Pylyshyn, 1973). In fact, a recent theory suggests that there may be many potential formats for the representation of sensory information (Palmiero et al., 2019) and I hypothesize that a person's dominant format may be driven by individual differences in the ability to simulate information in a sensory way. This leads to the question: How do you hold precise sensory information in memory for a short time? Find out, below!


Imagery tracking (demo only)

Can you smoothly track an imagined moving object with your eyes?

If you take a video of your eye movements while looking around your environment, you will notice certain patterns - a fixation around an interesting object, followed by a quick jump to another location, where you will fixate for a moment or two, and then make the next jump. The jumps your eyes make are called saccades. Tracking a moving object, such as a ball being passed back and forth between two people, elicits a smooth pursuit - meaning, your eyes can follow the ball without making saccades throughout its trajectory. Critically, a visual stimulus is thought to be required for smooth pursuit -- trying to track an imagined object will ultimately result in saccades (Spering & Montagnini, 2010).

Enter prophantasia -- the ability to project imagined objects into the environment. There is no objective test of prophantasia, which currently relies on subjective reports. My hypothesis is that if some people can actually experience imagined objects in the external environment, they should be able to perform smooth pursuit of an imagined moving object, thus measuring prophantasia. One previous study found that it is possible to smoothly track images experienced during lucid dreaming (LaBerge et al., 2018), suggesting a veridical, physical stimulus is not required for this type of eye movement. The demo below measures your ability to track a purely imagined object.


This is a temporary, non-experimental demo! I am currently looking for another webcam-based eyetracking website that can host this task. Please contact me if you know of anything :-)

This demo only works if you are on a computer with a webcam.

Aphantasia in mental healthcare

What is the role of mental imagery in mental healthcare experiences?

Visualization is a popular technique used in mental wellness and therapy, but what does this mean for the nearly 5% of the population who have an inability visualize - aphantasia?

In collaboration with the largest non-profit dedicated to aphantasia awareness, researchers with expertise in mental health and mental imagery are making it their job to find out. We are conducting a study to find out the potential challenges when seeking mental healthcare with aphantasia, which should inform next steps for improving personalized mental healthcare.

This study is now closed for new data collection.

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