Aims:

• the question about the categorization of illusions can tell us about the role of illusions in the scientific study of perception, which at the same time can be entertaining or puzzling and a challenge to our understanding of the visual system.
• it gives an opportunity to 'collect', 'compare' and 'contrast' - and in doing so get a glimpse of the huge range of illusions that we can experience in arts, life, and science labs
• it also offers you a chance to investigate the consequences of the processing mechanisms underlying the perception of illusions - and what that means for our understanding of the world
• in writing this essay, you should practice the use of textbook and journal article sources to be combined with your own critical thinking, to create a interesting narrative and provide the reader with valuable scientific information
• most importantly, I hope that this essay will allow you to apply some critical thinking, so that you develop your own ideas on how all these creatures called illusions can be sorted into a helpful and meaningful system ...

Context

The topic relates to the not always obvious but very common experience of visual illusions, which is not only a technique used by artists to create experiences away from physical reality, but which also has a huge relevance for Psychology as a clue to understand how sensory systems work, and for us as human to realize how surprisingly difficult it can be to be confident about the nature of the world. In this sense it is an important philosophical question, which could make us think 'never believe what you see!'.

And here you can download your essay instruction sheet...

What to do

Think about some of the illusions you have seen during the lectures, and perhaps during your background reading (many Psychology textbooks are populated with illusions, and have you noticed the mural next to the entrance of the Psychology building?). From your initial exploration, you should choose your favorite illusion and bring it to tutorial to discuss with your tutor and your peers. (You can also upload your illusion to the Student Forum, and we should end up with a nice collection!)

After the tutorial, try to explore a wider variety of illusions (see sources below, and spend some time - not too much, though - exploring such phenomena on the web) and think about possible ways to arrange them in categories, such as the following:

• the strength of the illusions: very subtle or massively strong
• created by image changes in space or time ?
• timing: transitory or stable
• the sensory domain: luminance, colour, depth, etc.
• popularity ?
• possible applications (for instance, as party trick, but what else?)

And many more - just be creative! Then consider which of these categories make sense, which ar useless or sully, and what you can learn from each of these categories. Then decide which one you want to use to organize you 'Zoo of Illusions'!

Don’t worry, you don’t need to cover all of these aspects, a 1500 word essay certainly can only scratch the surface. At some point you should, however, define what illusions are and what they have in common. You also should describe in which ways illusions can differ from each other and what links them together. At the end, you could present some of your thoughts to evaluate how illusions help psychologists to understand human behaviour and the mind.

Have fun, but don't get lost on the internet!

Sources

The basic framework fro this essay is covered in the lecture on the 28th of October, and can be found on the webpage for lectures 1 - 4 (many visual illusions demonstrated in 3 & 4) (access from http://www.pc.rhul.ac.uk/staff/J.Zanker/PS1061/PS1061.htm). Starting from the lecture material, the best way forward, if you want to drill deeper into the material, is to read the chapters on hearing in the main textbook (Zanker 2010) and/or start browsing Goldstein (2007), to collect information and ideas that can be relevant for your essay. Then you can move on to other sources, some of which ar listed below, to gain deeper understanding of some illusions, or expand your overview about the variety of such phenomena. When you search the internet for additional material, make sure that you always end up with reliable sources (i.e. material published in academic journals that you can include as references).

Reading materials (core texts in library, partially available from virtual resources room):

•   main textbook : Zanker, J.M. (2010) Sensation, Perception, Action - an evolutionary perspective. Palgrave (152.1 ZAN) : chapters 3 and 6 (& 13 ?)
•   Goldstein E. B. (2007) Sensation and Perception (7th ed.), Wadsworth (152.1 GOL);

Further reading (available from virtual resources room, library electronic journals, or internet):

• Anstis SM, Rogers B and Henry J, 1978 "Interactions between simultaneous contrast and coloured afterimages” Vision Research 18, 899-911, click here
• Fiorentini, A., et al., The Perception of Brightness and Darkness: Relations to Neuronal Receptive Fields, in The Neurophysiological Foundations of Visual Perception, L. Spillmann and J.S. Werner, Editors. 1989, p129-161, click here
• Gregory, R.L. (1968) 'Visual illusions' Scientific American 219: p. 66-76, click here
• Jameson D and Hurvich LM, 1964 “Theory of brightness and colour contrast in human vision” Vision Research 4: p. 1-22, click here
• Kanizsa G, 1976 "Subjective Contours" Scient.Am. 234: p. 48-52, click here
• Ramachandran V S, 1988 "Perceiving shape from shading" Sci.Am. 256, 8 , 76-83, click here
• Ramachandran V S, Anstis S M, 1986 "The perception of apparent motion" Sci.Am. 254, 6 80-87, click here
• Ratliff, F., Contour and Contrast. Scient.Am., 1972. 226: p. 90-101, click here
• Schrauf M, Lingelbach B, Wist E R, 1997 "The Scintillating Grid Illusion" Vision Res. 37, p. 1033-1038, click here
• White M, 1979 “A new effect of pattern on perceived lightness” Perception 8: p. 413-416, click here

And there are plenty of Websites dedicated to illusions, such as:

• 92 Visual Phenomena & Optical Illusions by Michael Bach

A note on Plagiarism

Plagiarism consists of a person presenting another person’s ideas, findings or work as their own by copying or reproducing the work without due acknowledgement of the source. The University regards plagiarism as a very serious offence. At the very least, it is a misuse of academic conventions or the result of poor referencing practice. Where it is deliberate and systematic, plagiarism is cheating.

By completing your submission declaration, you are confirming in written form that the work you are submitting is original and does not contain any plagiarised material.

When plagiarism is suspected in any work, it will be scrutinized further in line with college policy. Furthermore, to assist with plagiarism detection the Department is implementing random checks of all coursework. We routinely check from the electronically submitted copies of coursework essays approx.10% of all submissions, selected at random.

back to course outline
last update 18-10-2011
Johannes Zanker