Overview
This lecture explains perception—how our brains organize and interpret sensory information—and explores the psychological factors, visual illusions, and depth cues that shape how we experience the world.
Perceptual Set and Expectations
- Perception is influenced by expectations, experiences, mood, and cultural norms.
- Perceptual set refers to psychological factors that shape how we interpret sensory input.
- Expectations and context can change what we perceive in ambiguous images.
- Emotions and motivations can alter perceptions, such as judging a hill steeper when sad or alone.
Form Perception and Grouping
- Our brain organizes sensory input into meaningful objects using form perception.
- Figure-ground relationship is how we distinguish objects (figure) from backgrounds (ground).
- Grouping rules help organize stimuli: proximity (grouping close items), continuity (seeing smooth patterns), and closure (filling gaps to see complete objects).
- Optical illusions demonstrate how easily our visual perception can be tricked.
Depth and Motion Perception
- Depth perception lets us see the world in three dimensions and judge distances.
- Binocular cues, like retinal disparity, require both eyes and help gauge close distances.
- Monocular cues for depth include relative size, linear perspective, texture gradient, and interposition.
- Motion perception estimates speed and direction; larger objects seem to move slower than small ones at the same speed.
Perceptual Constancy
- Perceptual constancy allows us to recognize objects regardless of distance, angle, lighting, or changes in appearance.
- Types include size constancy, shape constancy, and color constancy.
Key Terms & Definitions
- Perception — the process of organizing and interpreting sensory information to make it meaningful.
- Perceptual set — psychological factors (expectations, context, culture, emotion) that influence perception.
- Figure-ground relationship — distinguishing an object from its background.
- Retinal disparity — slight difference in images between eyes, used for depth perception.
- Monocular cues — depth cues available to each eye alone, such as relative size or linear perspective.
- Perceptual constancy — ability to recognize objects as constant despite changes in sensory input.
Action Items / Next Steps
- Review examples of optical illusions and try to identify figure-ground and grouping principles.
- Practice identifying monocular and binocular depth cues in real-world scenes.
- Read the next chapter on sensory processing for further understanding.