Chapter 14 Bottleneck - memory (INCOMPLETE)

What does it take to form a memory?

If I ask you about your memory, you’ll probably assume that I’m asking you about things pretty far in the past.. a different day, at least. But memory is required even for you to report something you saw a few seconds ago. In the laboratory, researchers have devised situations in which you will occasionally forget things that happened just two seconds ago.

One thing researchers do in their experiments is show people random, unrelated stimuli. That way, people can’t use their knowledge of the way the world usually works to reconstruct what must have happened. In the real world, if I hear the doorbell ring and ten seconds later find myself holding a package addressed to me, I can guess that probably what happened is I went to the door and got the package there. These standard sorts of sequences of events can help our brains reconstruct events in an act of remembering based on only fragments.

Another thing that researchers do is present stimuli only briefly. Let’s say I ask you to remember a photo like this.

As you examine the photograph, various descriptions may come to your mind. For me, I notice the white and black pincer-shaped wing markings, and the fuzz-tipped feathery wings blending into a fuzzy body. You might start making various associations, like with an eagle’s talons for the wing markings, a stuffed animal for the body, and a fur coat for the white edges of the wings. The longer you look at it, the more details you notice and think about, which creates more and more bits of memory that later can help you remember the image.

However, if you are shown an image only very briefly, then you have less chance to form memories about it. The twin features of brief presentation and unrelated stimuli are what help researchers probe how memory works even at the short timescale of seconds.

In most memory experiments, the stimuli are much more boring than my photo of the moth I showed you above. This is mainly for standardisation purposes, so that stimuli are similarly memorable and thus can easily be swapped with similar results obtaining. For example, often the stimuli are individual letters.

Below is an example movie with a rapid series of letters presented. When you watch the movie below, look out for and try to remember the letter that is circled.

If the movie didn’t work, you can watch it here.

Hopefully you were able to see which letter was circled. However, the act of trying to remember that letter can impair your memory of subsequent letters in the stream.


Goodbourn, P. T., P. Martini, M. Barnett-Cowan, I. M. Harris, E. J. Livesey, and A. O. Holcombe. 2016. “Reconsidering Temporal Selection in the Attentional Blink.” Psychological Science 27 (8): 1146–56.