Suggestions for Essay Topics

• Some psychologists believe that the brain stores much more information than we can consciously recall -- for example, photorealistic images of every moment since birth (or since conception). Although normally repressed, this information may be made available under the right circumstances -- for example, it may be elicited by hypnosis, by certain drugs, or by intense psychoanalysis.

  Comment on the information storage that would be required, and compare it with any estimate you can make of the information capacity of the brain.

• In this lecture, we noted that the information content of a picture on a black-and-white monitor with 1,000,000 pixels is 1 megabit. What is the information content of a picture on a 8-bit colour monitor?

  A naive argument is to say that each pixel can have one of 2 to the power 8 colours, and therefore the total number of possibilities is 2^8 to the millionth power. However, this is not correct (at least for most colour monitors). It's not correct because most 8-bit monitors have an adjustable colour map. Each pixel on the monitor is theoretically capable of being set to any one of 2^24 colours -- any value from 0-255 for each of the hues red, green and blue -- and the choice of a particular colour map corresponds to restricting the pixels to a subset of 256 colours selected from this larger set of 2^24. Thus the selection of a particular picture can be described by the following diagram:

  colour.eps

• What is the information content of a one-minute video sequence? State clearly any assumptions you are making.