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 provided white noise over headphones.

10 minutes

50 minutes

The above buttons play continuous white

noise. White noise can be played in combi-

nation with the flicker to enhance Ganzfeld imagery. Listen with headphones for the most immersive experience.

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.


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.

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.

If you would like to go straight to the demo, click this button - it will open a new window and you can enter a memorable word where it says "participant" (do NOT enter any self-identifying information, as this experiment is public!):

If you would like to fill out some questionnaires about your imagery for data collection purposes after you have performed the task, click this button: