Psychology Chapter on Sensation and Perception

Why Study Sensation and Perception?

• Sensation and perception influence our behavior and mental processes.
• They provide a bridge between biology and cognition, bridging the gap between how we think and how we behave.

The ABC’s of Sensation

• Sensation is the process of converting outside stimuli into neural signals in the brain.
• The sense organs (eyes, ears, nose, skin, and taste buds) detect these stimuli.
• Transduction is the process of converting outside stimuli into neural activity.
• Sensory receptors are specialized neurons stimulated by specific types of energy (light, vibrations, pressure/temperature, chemical substances)
• Synesthesia is a condition where signals from different senses are processed differently, resulting in mixed sensations.

Weber's Law and Just Noticeable Difference

• Weber's law of just noticeable difference (JND) is the smallest difference between two stimuli that can be detected 50% of the time.
• The JND is always a constant percentage of the original stimulus.

Absolute Threshold and Subliminal Perception

• The absolute threshold is the lowest level of stimulation that can be consciously detected 50% of the time.
• Subliminal stimuli are stimuli below the level of conscious awareness that activate sensory receptors.
• Subliminal perception is the unconscious processing of sensory information.

Signal Detection Theory

• Signal detection theory is a method to assess the accuracy of judgments under uncertainty.
• It involves analyzing "hits", "misses", "false alarms", and "correct rejections".
• The theory helps understand how people detect stimuli in their environment.

Habituation and Sensory Adaptation

• Habituation is the tendency of the brain to ignore constant, unchanging information.
• Sensory adaptation is the tendency of sensory receptor cells to become less responsive to unchanging stimuli.

The Science of Seeing

• Light is a form of electromagnetic radiation that travels in waves.
• Wavelengths are interpreted as color.
• Amplitude is interpreted as brightness.
• The eye has specialized structures for processing light.

The Retina

• Contains photoreceptor cells called rods and cones.
• Rods are responsible for vision in low light.
• Cones are responsible for color vision and visual acuity.

Theories of Color Vision

• Trichromatic Theory: The eye has three types of cones (red, blue, and green) sensitive to different wavelengths of light.
• Opponent-Process Theory: Colors are perceived in opposing pairs (red-green, blue-yellow, and black-white).

Color Blindness

• It is the inability to perceive color differences.
• Caused by defective cones in the retina.
• It is a genetic condition.

Types of Color Blindness

• Achromatopsia (monochromatic vision): Complete lack of color perception.
• Dichromatic vision: One cone type is not functioning properly.
• Protanopia: Red cones are deficient.
• Deuteranopia: Green cones are deficient.
• Tritanopia: Blue cones are deficient.

The Hearing Sense

• Audition is the biological processing of sound waves.
• Sound waves are vibrations of molecules in the air.
• Wavelength is interpreted as pitch.
• Amplitude is interpreted as loudness.
• Timbre is interpreted as the richness of the sound.

Structure of the Ear

• Outer Ear:
  • Pinna focuses soundwaves into the auditory canal.
  • Auditory canal transmits sound waves to the eardrum.
• Middle Ear:
  • Contains three tiny bones (ossicles): hammer, anvil, and stirrup.
  • They amplify vibrations from the eardrum.
  • The stirrup vibrates the oval window, which separates the middle ear from the inner ear.
• Inner Ear:
  • Contains the cochlea, filled with fluid.
  • Vibrations of the oval window cause fluid to vibrate.
  • This fluid movement stimulates hair cells within the organ of Corti, causing them to send neural signals.
  • The auditory nerve transmits these signals to the brain.

Perceiving Pitch

• Pitch is the psychological experience of sound frequency.
• Place Theory suggests different pitches stimulate hair cells at different locations on the organ of Corti.
• Frequency Theory states pitch depends on the speed of vibrations of the basilar membrane.
• Volley Principle explains how hair cells fire in a volley pattern for pitches between 400 -4,000 Hertz.

Sound Localization

• This is the ability to determine the origin of a sound based on ear's reception of loudness and timing.

Types of Hearing Impairments

• Hearing impairement is a broad term for difficulties hearing.
• Conduction deafness is caused by problems with sound transmission in the outer or middle ear.
• Sensorineural deafness (nerve deafness) is caused by damage to the inner ear, auditory nerve or auditory processing areas in the brain.