Perception

Perception is the organisation and interpretation of the information we receive through our senses.

Monocular Depth Cues:

A way of detecting depth or distance, which will work with just one eye.

Monocular Depth Cues:

• Height in Plane
• Relative Size
• Occlusion
• Linear Perspective

Binocular Depth Cues:

A way of detecting depth or distance, which requires two eyes in order to work.

Binocular Depth Cues:

• Convergence
• Retinal Disparity

Height in Plane

How high an object appears in the image. You will find that things further up in the image often appear to be higher up.

Relative Size

How large an object appears in an image. You will find that things that are closer to you seem to be larger.

Occlusion

An object which is covering up another object. You will find that the one in the front seems to be closer whereas the one which is covered up seems to be further away.

Linear Perspective

The straight lines seem to be pointing towards to a single point on the horizon. The point is known as the 'vanishing point' because the lines disappear when they reach closer to it. The vanishing point is useful if you want to show distance in a landscape.

Convergence

A form of depth perception which uses how eye muscles focus on images. We focus our eyes differently to see things that are closer to us, to how we focus to see things that are further away. Our brain detects these differences in how the muscles are working, and uses it as a cue to distance.

Retinal Disparity

Another form of depth perception which compares the images from two eyes - side by side. If something is close to us, there is quite a difference in what our two eyes see. If it is further away, there will be less of a difference the images. After about 10 metres, the difference is hardly noticeable.

Gibson's Direct Theory of Perception

Direct Perception is the idea that we simply perceive by using the information we receive through our senses. This gives us enough information to make sense of the real world. Gibson believed that the key to understanding perception is to remember what it is used for. For example, if we are moving along a road, the visual image we receive changes. Things that are closer to us appear to kove fast as we go past them, while things that are further away do not seem to move as much. This is know as Motion Parallax. It combines with other depth cues to help judge distance accurately, only when we're moving. 

Evaluation of the Direct Theory of Perception

• The theory does indicate that some perceptual set abilities might be due to nature, and that we do not need to use past experiences to perceive the world around us. The evidence from infant research shows that depth perception might be innate/inborn.
• The theory focuses on movement and how perception depends on the way visual cues change as we move. This is a strength as we never perceive anything from a static point of view.
• The theory suggests that sensation and perception are the sampe process, but we know from illusions that they are seperate processes.
• It is also the case that we know our past knowledge and information affects some of pur perception. We often interpret something depending on what we expect it to be rather than what it actually is.

Evaluation of Gregory's Direct Theory of Perception

• There is a lot of evidence to support the idea, that the interpretations we make of the sensations we receive, are affected by our past experiences. Key Research Studies suggest that the perceptions of participants were affected by their expectations or how they were feeling at the time of the study. This supports the idea that nurture can have an effect on perception.
• Not everyone agrees with the explanations given for the effects of some illusions. Some have suggested that the Muller-Lyer Illusion works because the arrowheads on the lines make them look like the near edge of a building. So we think one line might be nearer to us than the other.
• Both Nature and Nurture have an effect on the way the sensations we receive become our perception of the world around us.

Nature Vs. Nurture

• Nature

The idea that our behaviour and characteristics are inherited.

• Nurture

The idea that our behaviour and characteristics are influenced by our environment.