Memory demos

Change blindness

Change blindness is a great way to demonstrate sensory memory. Sensory memory is very short-lived—less than a second for images—and most of the information it takes in doesn't enter our conscious awareness.

When we see two slightly different images, one right after the other, it is very easy to pick out the difference. But adding a 0.6-second flash in between makes the task much harder. That quick flash is long enough for most of the information in our visual sensory memory to fade. It's only when we intentionally focus our attention on specific visual elements that we can see the change.

Related content

To learn more about sensory memory, working memory, and more, visit Types of Memory.

Stroop test

The Stroop test is a measure of selective attention, which uses working memory. The test uses a list of names of colors, like the image shown here. But instead of reading the words, the person being tested must say the color of the letters. When the colors and words are conflicting, the brain needs to work hard to filter out the competing signals. The resulting delay is called the Stroop Effect.

Download the pdf file for colored word lists and instructions to guide you through a hands-on Stroop test demo.

Inattentional blindness

Attention is an important feature of working memory that helps to bring information into our conscious awareness. Attentional control helps us filter out distractions—like when we focus on reading a book in a crowded, noisy room.

The flip side of attentional control is that when we are focused on a task, we may not notice important signals outside of that task. If we are focused on reading, for example, we may not notice an important announcement even though our ears are hearing it.

Inattentional blindness is the failure to notice something, even when it's directly in our line of sight. Inattentional blindness can happen when we are highly focused on a task. In a famous experiment, when test subjects were chasing a runner through a college campus, more than one-third did not see a staged fight that they ran past.

Inattentional blindness is a fact of life. We like to think that we are aware of our surroundings, but we actually notice very little. There is simply too much information for the brain to process.

Magicians and pickpockets are experts at manipulating our attention and taking advantage of inattentional blindness.

Related links

How many changes can you spot in this "Whodunnit" video?

Count how many times the players in white shirts pass the ball

More videos from this project



Chabris, C.F., Weinberger, A., Fontain, M. & Simons, D.J. (2011). You do not talk abut Fight Club if you do not notice Fight Club: inattentional blindness for a simulated real-world assault. i-Perception, 2, 150-153. doi: 10.1068/i0436

Stroop, J.R. (1935). Studies of interference in serial verbal reactions. Journal of Experimental Psychology, 18, 643-662. (PDF)