Conceptions of Object Perception (cognitive psychology)

Four conceptions of object perception: Conceptions of
•Helmholtz’s unconscious inference: perceiving what is most likely Object
•The Gestalt laws of organization:
Perception
•Law of good continuation
•Law of Pragnanz (principle of simplicity)
•Law of similarity
•Regularities in the environment
•Physical regularities:

•Verticals and horizontals (oblique effect)
•Light-from-above effect
•Semantic regularities: scene schema
•Bayesian inference: prior probability; likelihood; conclusion

The approaches of Helmholtz, regularities, and Bayes all have in common the idea that we use data about the environment,
gathered through our past experiences in perceiving, to determine what is out there. Top-down processing is therefore an
important part of these approaches.

The Gestalt psychologists, in contrast, emphasized the idea that the principles of organization are built in.

Conceptions of Object Perception

Helmholtz’s Theory of Unconscious Inference

Unconscious inference, in which our perceptions are the result of unconscious
assumptions, or inferences, that we make about the environment. Thus, we infer that it is
likely that figure 3.14a is a rectangle covering another rectangle because of experiences we
have had with similar situations in the past.

Simplest and most effective Can be too subtle (halus) ;
Must not use colour alone

Primarily for banners and seperators Popup menus and other windows

(but other geometric arrangements are possible)

Conceptions of Object Perception

The Gestalt Principles of Organization Apparent Movement
perceptions were formed by “adding up” sensations
Modern examples of

apparent movement

are electronic signs

that display moving

advertisements or

news headlines, and

movies. The perception

of movement in these

displays is so

compelling that it is

difficult to imagine that

they are made up of

stationary lights

flashing on and off (for

the news headlines) or

still images flashed one

after the other (for the

movies).

Can see
anything?

The Principles of Good Continuation

states the following: Points that, when connected, result in straight or smoothly curving lines are seen as belonging together, and
the lines tend to be seen in such a way as to follow the smoothest path. Also, objects that are overlapped by other objects are
perceived as continuing behind the overlapping object.

Taking Regularities of the environment into account



shadow

shadow

Example of Bayesian inference with a prior distribution, a posterior distribution, and a likelihood function.
The prediction error is the difference between the prior expectation and the peak of the likelihood function
(i.e., reality). Uncertainty is the variance of the prior. Noise is the variance of the likelihood function.