Medical Psychology - Perception

Medical Psychology - Perception

• Perception is a process that gives meaning to sensory information.
• Perception is influenced by experience and cultural norms.
• Perception is also influenced by expectations, emotions, and motivations.
• Perceptions are not always accurate reflections of reality.

Types of Illusions

• Geometric illusions: These illusions involve distorted images where shapes or lines appear different than they actually are. A common example is the Ponzo illusion, where converging lines make one line appear longer than another, even though they are the same length.

• Ambiguous figures: These images can be perceived in more than one way. A classic example is the Necker cube, which can be perceived as a cube facing either up or down.

• Fictitious Percepts: These occur when we perceive something that is not actually there.

Visual Constancies

• Shape constancy: The ability to perceive objects as having a consistent shape even when the view of them changes. This is illustrated by an open door, which appears rectangular, despite changes from different perspective points.

• Color constancy: The ability to perceive color as consistent in spite of changes in lighting conditions.

Gestalt Rules of Form Perception

• Figure-ground relationship: The process of organizing a scene into a figure (main objects) and ground (the background or surroundings).

• Grouping: The ability to organize visual elements into a unified whole, based on things like proximity or similarity. Examples include visual items grouped by similarity (similar shape, color, etc.).

• Similarity: The tendency to perceive things that share similar characteristics (e.g., shape, color, size) as belonging together. This principle relates visual elements.

• Continuity: The tendency to perceive continuous lines or patterns rather than discontinuous or broken ones.

• Connectedness: The tendency to perceive visual elements that are touching as belonging together. An example is the Olympic rings.

Depth Perception Cues

• Linear perspective: Parallel lines appear to converge as they recede into the distance.

• Two-height in plane: Objects higher in the visual field are perceived as being farther away than objects lower in the visual field.

• Relative size: When we expect objects to be the same size, differences in apparent size suggest distance.

• Superimposition/Overlap: Objects that partially obscure or overlap others are perceived as being closer.

• Texture gradients: Details on a surface become less noticeable as distance increases.

Perception Theories

• Constructivist Theory: This theory suggests that perception is built based on past experiences and expectations. Perceptions depend partly on a person's past experiences while looking at elements. Top-down processing is an essential aspect of the Constructivist theory.

• Nativist Theory: This theory proposes that perception is innate and immediate. Our inherent perceptual mechanisms, largely independent of experience, allow us to rapidly perceive our surroundings. Bottom-up processing is the base of this theory.

Criticisms of Perception Theories

• The theories are not mutually exclusive. It is believed that in reality, perception is a combination of top-down and bottom-up processing, utilizing both past experience and immediate sensory information.