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.
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.
can you smoothly track an imagined moving object with your eyes?
This experiment only works if you are on a computer with a webcam.
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.
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!
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 experiment below tests your ability to track a purely imagined object.