physics

Motion aftereffect

Motion aftereffect is a physics topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Motion aftereffect rather than just read about it. In short: The motion aftereffect (MAE) is a visual illusion experienced after viewing a moving visual stimulus for a time (tens of milliseconds to minutes) with stationary eyes, and then fixating a stationary stimulus. The stationary stimulus appears to move in the opposite direction to the original (physically moving) stimulus.

Key takeaways

Motion aftereffect belongs to physics; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Motion aftereffect to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Motion aftereffect from memory before moving on to harder problems.

Reference excerpt

The motion aftereffect (MAE) is a visual illusion experienced after viewing a moving visual stimulus for a time (tens of milliseconds to minutes) with stationary eyes, and then fixating a stationary stimulus. The stationary stimulus appears to move in the opposite direction to the original (physically moving) stimulus. The motion aftereffect is believed to be the result of motion adaptation. For example, if one looks at a waterfall for about a minute and then looks at the stationary rocks at the side of the waterfall, these rocks appear to be moving upwards slightly. The illusory upwards movement is the motion aftereffect. This particular motion aftereffect is also known as the waterfall illusion. Another example can be seen when one looks at the center of a rotating spiral for several seconds. The spiral can exhibit outward or inward motion. When one then looks at any stationary pattern, it appears to be moving in the opposite direction. This form of the motion aftereffect is known as the spiral aftereffect. It also sometimes works with bright colors: if one stares at one for too long, then look at its opposite, it will appear to grow or shrink. This is sometimes considered a case of normal afterimage.

Explanation Neurons coding a particular movement reduce their responses with time of exposure to a constantly moving stimulus; this is neural adaptation. Neural adaptation also reduces the spontaneous, baseline activity of these same neurons when responding to a stationary stimulus (see, for example, Barlow & Hill, 1963; Srinivasan & Dvorak, 1979; Glasser, Tsui, Pack, & Tadin, 2011). One theory is that perception of stationary objects—for example, rocks beside a waterfall—is coded as the balance among the baseline responses of neurons coding all possible directions of motion. Neural adaptation of neurons stimulated by downward movement reduces their baseline activity, tilting the balance in favor of upward movement.

History Aristotle (approx. 350 B.C.) reported illusory movement after viewing constant movement, but he did not specify its direction. The first clear specification of the motion aftereffect was by Jan Evangelista Purkyně (1820), who observed it after looking at a cavalry parade. Robert Addams (1834) reported the waterfall illusion after observing it at the Falls of Foyers in Scotland. According to Verstraten (1996), the term waterfall illusion was coined by Thompson (1880). According to Wade, Thompson, and Morgan, (2014), the most comprehensive single article on the phenomenon is by Gustav Adolf Wohlgemuth (1911).

See also Afterimage Motion perception

References

Sources Addams, R. (1834). An account of a peculiar optical phenomenon seen after having looked at a moving body. London and Edinburgh Philosophical Magazine and Journal of Science, 5, 373–374 Aristotle (approx. 350 B.C.) Parva Naturalia. Barlow, H.B., & Hill, R.M. (1963). Evidence for a physiological explanation of the waterfall illusion. Nature, 200, 1345-1347. Glasser, D. M., Tsui, J. M., Pack, C. C., & Tadin, D. (2011). Perceptual and neural consequences of rapid motion adaptation. PNAS Plus, 108(45), E1080–E1088. doi:10.1073/pnas.1101141108 Petersen, S. E., Baker, J. F., & Allman, J. M. (1985). Direction-specific adaptation in area MT of the owl monkey, Brain Research, 346, 146-150. Purkinje, J. E. (1820) Beiträge zur näheren Kenntniss des Schwindels aus heautognostischen Daten. Medicinische Jahrbücher des kaiserlich-königlichen österreichischen Staates, 6, 79–125. Srinivasan, M. V., & Dvorak, D. R. (1979). The waterfall illusion in an insect visual system. Vision Research, 19, 1435-1437. Thompson, P. (1880). Optical illusions of motion. Brain, 3, 289-298. Tootell, R. B., Reppas, J. B., Dale, A. M., Look, R. B., Sereno, M. I., Malach, R., Brady, T. J., & Rosen, B. R. (1995), Visual motion aftereffect in human cortical area MT revealed by functional magnetic resonance imaging, Nature, 375", 139-141. Verstraten, F. A. J. (1996). On the ancient history of the direction of the motion aftereffect. Perception, 25, 1177-1188. Wade, N. J., Thompson, P., & Morgan, M. (2014). The after-effect of Adolf Wohlgemuth’s seen motion. Perception, 43, 229-234. doi: 10.1068/p4304ed Wohlgemuth, A. (1911). On the after-effect of seen movement. British Journal of Psychology Monograph Supplement, 1-117.

Bibliography Mather, G., Verstraten, F., & Anstis, S. (1998). The motion aftereffect: A modern perspective. Cambridge, Mass: MIT Press

External links

"Strobe Illusion" – an example of this effect (enable JavaScript to view). "Spiral aftereffect" – another example of this effect (enable JavaScript to view).

Worked examples

Example 1 — a first encounter with Motion aftereffect

Start with the simplest possible case. Write down what Motion aftereffect claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In physics, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Motion aftereffect before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Motion aftereffect ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Motion aftereffect

In research: Motion aftereffect appears in physics research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Motion aftereffect in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Motion aftereffect is common in secondary-school and first-year university syllabi. It links to neighbouring topics Optical illusions, so understanding it makes those chapters shorter.
In everyday life: Look for Motion aftereffect outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Motion aftereffect in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Motion aftereffect means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Motion aftereffect out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Motion aftereffect in simple terms?

Why does Motion aftereffect matter?

Because it connects several physics ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Motion aftereffect?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Motion aftereffect.