Psychology Chapter 2: Sensation and Perception

Sensation and Perception

• Knowledge originates from perception
• Basic Senses: Vision, Hearing, Smell, Taste, Touch
• Sensation involves detecting stimuli, converting them to electrical signals, and transmitting them to the brain.
• Sense organs include eyes, ears, nose, tongue, skin, and internal organs.
• Perception is the brain's interpretation of sensory input.

Psychophysics

• Studies the relationship between physical stimuli and sensations.
• Examples of physical stimuli and how they are measured:
  • Light: brightness, color
  • Sound: volume, pitch
  • Pressure: weight
  • Taste: sweetness, saltiness etc.
• Transduction: converting physical energy to neural signals. Sensory receptors convert various energy forms (sound, light, pressure, chemicals) into nerve impulses.

Sensation Thresholds

• Absolute Threshold: minimum stimulus needed for detection 50% of the time.
• Just Noticeable Difference (JND) the minimum difference between two stimuli that can be detected 50% of the time.

Weber's Law

• The JND is a constant proportion, not a constant amount, of the original stimulus intensity.

Signal Detection Theory

• Predicts how and when we detect a signal amidst noise (background stimulation).
• No single absolute threshold; detection changes depending on factors.

Somesthetic Senses

• Vestibular: balance and position in space, affected by the semicircular canals (fluid filled canals in the inner ear).
• Kinesthetic: body position and movement.
• Touch: pressure, warmth, cold, pain.

Body Position and Movement

• Kinesthesis: senses position and movement of body parts.
• Vestibular sense: body movement and position relative to gravity, critical for balance.

Vestibular System and Motion Sickness

• Motion sickness occurs when vestibular system sensations conflict with visual and body sensations. This is called sensory conflict.

Auditory Sensation

• Transduction of air pressure vibrations into neural impulses.
• Sound waves comprise different frequencies and amplitudes.
  • Amplitude: perceived as loudness
  • Frequency: perceived as pitch
• Sound localization: the brain uses differences in intensity and arrival time of sound waves from each ear to pinpoint source.

Factors Influencing Perception

• Attention
• Organization
• Expectations
• Motivation

Perceptual Attention

• Selective attention: focusing on one stimulus, like the cocktail party effect.
• Divided attention: splitting focus between multiple tasks.
• Inattentional blindness: inability to perceive stimuli based on attention limits. Change blindness is a type of inattentional blindness.

Perceptual Constancies

• Ability to perceive stimuli consistently despite changes in sensory input.
  • Color constancy: perceived color remains the same even with varying light.
  • Size constancy: perceived size remains the same even at different distances.
  • Shape constancy: perceived shape remains the same despite changes in viewing angle.

Depth Perception

• Ability to judge distance and perceive the world in three dimensions.
• Visual Cliff experiments: studied depth perception in infants.

Monocular Depth Cues

• Distance cues based on input from one eye.
  • Accomodation: lens adjustment for focusing on different distances.
  • Pictorial depth cues: provide info about space, depth, and distance.
    • Linear perspective: parallel lines converging.
    • Relative size: closer objects appear larger.
    • Relative height: objects higher in frame seem farther.
    • Light and shadow: simulate light sources.
    • Interposition: closer objects overlap further objects.
    • Texture gradients.

Binocular Depth Cues

• Distance cues based on input from both eyes.
  • Convergence: eyes turning inward for close objects.
  • Retinal disparity: different images from each eye creates depth perception.

Perceptual Expectations (Perceptual Set)

• Biased perception based on past experiences and expectations.

Top-Down vs. Bottom-Up Processing

• Top-down: perception guided by expectations and knowledge.
• Bottom-up: perception guided by stimulus features.
• Conceptually Driven: Whole to parts
• Data Driven: Parts to Whole

Parallel Processing

• Simultaneous processing of different aspects of a stimulus.

Perceptual Adaptation

• Adjustment to altered sensory input.

Explore the fascinating world of sensation and perception in this quiz based on Chapter 2 of Psychology. Dive into the basic senses, psychophysics, and learn about sensation thresholds. Test your understanding of how we detect and interpret stimuli from our environment.