Describe example context effects in perception.

Describe example context effects in perception.

A context effect describes the influence of environmental factors on one's perception of a stimulus. It is considered to be a part of top-down design.

One of the simplest examples is that of brightness contrast. The apparent brightness of a stimulus depends not only on its own luminance but also on that of the surrounding stimulation. The same gray square looks whiter against a dark background and blacker when placed in a bright surround. Similarly, a white or gray patch will take on an apparent hue that is complementary to the colour of the surround.

In the Ebbinghaus illusion, it is perceived that the middle circle seems larger than that of the other picture atlthough it is the same. The context makes this differences (it's not us that just seems crazy!). Neurons in levels of processing distinguish this at a reasonable case. Another example would be the Escher: Sky and Water, we perceive those of geese at the top although at the bottom we see fishes. This also relies on context.

Our perception is among others influenced by our knowledge of the regularities in the environment. There are two types of such regularities - the physical regularities and the semantic regularities. The first ones refer to regularly occuring physical properties of the environment whereas the second refer to the characteristics associated with the functions carried out in different environments.

One of the first examples of the context effect was that shown by Palmer. In his experiment he has presented the participants with a context scene like a kitchen, and subsequently flashed some target objects, of which one was connected to the previously presented scene. The participants correctly recognised the object connected to the scene in the majority of cases, whereas the objects tht were not connected were correctly recognised only in the minority of cases.
This shows that the context we are experiencing influences our perception of objects.