Weber's Law

• First noted by Ernst Weber (1795-1878)
• Equation: JND = KI or K = JND/I
• The Weber fraction, K, varies for different sensory stimuli.

Perception

• What we perceive is more than what meets the eye (or the ear, or the skin, etc.)
• Perception is a product of sensory analysis, innate principles of organization, attention, & beliefs and knowledge.
• Perception is both "direct" and "constructive;" both "bottom-up" and "top-down."

Organizational Principles

• Figure vs. ground
• Principles of perceptual grouping
• proximity, similarity, closure, good continuation, common fate.
• Frames of reference
• Depth perception

Perceptual Grouping in Hearing

• Figure vs. ground: My voice vs. other noise.
• Proximity: Notes in a melody.
• Good continuation: First chair violin vs. others.
• Similarity: Soprano voices in chorus.
• Common fate: Rising notes.

Frames of reference

Depth Perception

• Problem: Retina is 2D, but perception is 3D.
• Monocular cues
• Binocular cues

Monocular Cues

• Relative size
• Interposition
• Texture gradient
• Linear perspective
• Motion parallax

Binocular Cues

• Convergence
• Disparity
• Two eyes, two views of the world.
• Demonstration.

Attention

• "Use it or lose it"
• Dichotic listening experiments
  • (pp 223-225 of Nairne)
• Form perception
• Change blindness

Dichotic listening

• Early studies indicated that nothing from the unattended ear was remembered.
• Later studies indicated that some meaningful information was retained (e.g., name).
• Newer studies indicate that most, but not all, information in unattended ear is lost.

Form perception

• Rock & Gutman (1981)
• Examine the red figures and rate them on how appealing they are. 1=not at all appealing; 9=very appealing.

Change blindness

• Levin & Simons
• "Door Study"

Knowledge & experience

• Letters & numbers
• Droodles
• Phonemic restoration

Summary

• Perceptual experience depends on the simultaneous & rapid integration of sensory information, innate principles of organization, attention, and experience.
• Perception is therefore both "bottom-up" and "top-down."