C5 PSYCH

Opening Questions

  • Essential questions about perception and sensation:

    • Is everything that is "sensed" also "perceived"?

    • Is the statement "Seeing is believing" accurate?

    • Reflection on interesting optical illusions and their implications on understanding human senses.

Overview of Topics

  • Section 5.1: Sensation versus Perception

  • Section 5.2: Waves and Wavelengths

  • Section 5.3: Vision

  • Section 5.4: Hearing

  • Section 5.5: The Other Senses

  • Section 5.6: Gestalt Principles of Perception

SENSATION

  • Definition:

    • Sensation occurs when sensory receptors detect sensory stimuli.

  • Sensory receptors: Specialized neurons responsive to specific types of stimuli.

  • Transduction:

    • The process of converting sensory stimulus energy into action potentials sent to the central nervous system.

  • Sensory systems include:

    • Vision

    • Hearing (audition)

    • Smell (olfaction)

    • Taste (gustation)

    • Touch (somatosensation)

    • Balance (vestibular sense)

    • Body position (proprioception)

    • Movement (kinesthesia)

    • Pain (nociception)

    • Temperature (thermoception)

SENSATION

Absolute Threshold

  • Definition: Minimum amount of stimulus energy needed for detection 50% of the time.

Subliminal Messages

  • Messages presented below the threshold of conscious awareness.

  • Action potentials generated, but not consciously perceived.

Just Noticeable Difference (JND)

  • Definition: Minimum difference in stimuli required to detect a change.

  • Depends on stimulus intensity.

  • Weber’s Law: Difference threshold is a constant fraction of the original stimulus.

PERCEPTION

  • Definition: Way sensory information is interpreted, organized, and consciously experienced.

Processing Types

  1. Bottom-Up Processing:

    • Perceptions built from sensory input.

  2. Top-Down Processing:

    • Interpretation of sensations is influenced by past knowledge and experiences.

  • Interaction between these processes can result in cognitive illusions, thereby revealing the nature of sensory perception.

FACTORS AFFECTING PERCEPTION

  1. Sensory Adaptation:

    • Not noticing constant stimuli over time.

    • Example: Unawareness of a clock ticking after prolonged exposure.

  2. Attention:

    • Inattentional Blindness: Failure to notice visible things when focused on other objects.

    • Example: Study indicating 1/3 participants missed a red cross while focusing on passing basketballs.

  3. Motivation:

    • Influencing perception such as imagining hearing a phone ring when expecting an important call.

    • Signal Detection Theory: Detection varies based on mental state.

  4. Beliefs/Values/Expectations:

    • Affect evaluation of experiences, e.g., those with positive attitudes towards low-fat foods enjoy the taste more.

  5. Life/Cultural Experiences:

    • Differences in experiences impact perception, e.g., Western cultures show more susceptibility to certain visual illusions.

MULLER-LYER ILLUSION

  • Lines appear different in length despite being equal due to external cues (arrows).

    • Applications: Understanding perceptual differences in 3D contexts as well.

COLOR CONSTANCY

  • Examination of image to understand color constancy in perception.

AMPLITUDE AND WAVELENGTH

  • Both visual and auditory stimuli represented as waves.

    • Amplitude: Height of the wave, measured from peak to trough.

    • Wavelength: Distance from peak to peak.

FREQUENCY

  • Definition: Number of waves passing a point over time (measured in hertz, Hz).

    • Relationship:

    • Longer wavelengths = lower frequencies

    • Shorter wavelengths = higher frequencies.

LIGHT WAVES

  • Visible Spectrum: Small section of the electromagnetic spectrum viewable by humans.

    • Humans can see wavelengths from $[380, 740]$ nm.

PERCEPTION OF COLOR

  • Wavelength and Perception: Different colors relate to wavelengths in light.

    • Longer wavelengths = Reds

    • Intermediate = Greens

    • Shorter = Blues and Violets.

  • Brightness/Intensity: Correlate with amplitude; larger amplitudes mean brighter intensity.

SOUND WAVES

Frequency and Amplitude

  • Frequency: Determines pitch (High frequency = high pitch; Low frequency = low pitch).

  • Audible Range: 20 – 20000 Hz for humans.

  • Amplitude: Loudness measured in decibels (dB).

  • Examples of sounds and their loudness in dB:

    • Typical conversation: 60 dB

    • Rock concert: 120 dB

    • Risk of hearing damage: 80 – 130 dB

    • Pain threshold: 130 dB.

SOUND WAVES

  • Logarithmic Scale: Non-linear scale with uniform increments in exponents.

VISION

  • Anatomy includes:

    • Cornea

    • Pupil

    • Iris

    • Lens

    • Retina

    • Fovea

    • Optic Nerve

  • Blind Spot: Exit point for information from the eye where visual receptors are absent.

PHOTORECEPTORS

  1. Cones:

    • Function in daylight; high-acuity color.

  2. Rods:

    • Operate under low-light; high-sensitivity for movement perception.

OPTIC CHIASM

  • Information from the right visual field sent to the left hemisphere, vice versa.

  • Important for processing visual information in the occipital lobe.

VISUAL PATHWAYS

  1. “WHAT” Pathway:

    • Responsible for object recognition, e.g., Fusiform Face Area (FFA).

  2. “WHERE/HOW” Pathway:

    • Involves spatial location and interaction planning with stimulus.

COLOR VISION

  1. Trichromatic Theory:

    • All colors from red, green, and blue mixtures.

  2. Opponent-Process Theory:

    • Colors paired in oppositions (black-white, yellow-blue, etc.) leading to afterimages (negative perception after stimulus removal).

DEPTH PERCEPTION

  • Ability to perceive spatial relationships in 3D through monocular and binocular cues.

  1. Monocular Cues:

    • Visual depth cues usable with one eye: linear perspective, interposition.

  2. Binocular Cues:

    • Relies on two eyes; includes binocular disparity for depth perception.

ANATOMY OF THE AUDITORY SYSTEM

  • Sections of the Ear:

    1. Outer Ear: Pinna, tympanic membrane.

    2. Middle Ear: Ossicles (malleus, incus, stapes).

    3. Inner Ear: Cochlea, basilar membrane.

AUDITORY TRANSDUCTION

  1. Sound waves vibrate the tympanic membrane.

  2. Ossicles amplify this to the oval window of the cochlea.

  3. Hair cells stimulate transduction into neural impulses.

  4. Auditory information travels through auditory nerve to the brain, specifically to the temporal lobe.

PITCH PERCEPTION

  • Theories:

  1. Temporal Theory:

    • Frequency coded by neuron activity levels; applicable up to 4000 Hz.

  2. Place Theory:

    • Different basilar membrane locations respond to varied frequencies; base = high, tip = low.

SOUND LOCALIZATION

  • Uses:

    1. Monaural Cues: One ear interactions with sounds.

    2. Binaural Cues: Two ears providing location coordinates based on sound intensity and timing differences.

HEARING LOSS

  • Types of Deafness:

  1. Congenital Deafness: Present from birth.

  2. Conductive Hearing Loss: Failure in vibrations; correctable with hearing aids.

  3. Sensorineural Hearing Loss: Failure transmitting signals/nerves; related to inner ear conditions and environmental factors.

TASTE (GUSTATION)

  • Six known taste sensations: Sweet, Salty, Sour, Bitter, Umami, potential fatty content.

  • Taste Buds: Groups of taste receptor cells with 10-14 day lifespans.

SMELL (OLFACTION)

  • Transduction process:

    1. Odor molecules activate receptors.

    2. Signals sent to olfactory bulb, limbic system, primary olfactory cortex.

  • Pheromones: Chemicals signaling reproductive status among species.

TOUCH

  • Receptors in skin include:

    1. Meissner’s corpuscles (pressure, low frequency).

    2. Pacinian corpuscles (transient pressure, high frequency).

    3. Merkel’s disks (light pressure).

    4. Ruffini corpuscles (stretch).

THERMOCEPTION & NOCICEPTION

  • Free nerve endings for:

  1. Thermoception: Temperature sensing.

  2. Nociception: Harm and pain signaling to the brain.

PAIN PERCEPTION

  • Different types:

    1. Inflammatory pain indicates tissue damage.

    2. Neuropathic pain involves neuron damage.

    3. Congenital Insensitivity to Pain: A rare condition where individuals can't feel pain but can detect temperature/pressure.

VESTIBULAR SENSE

  • Contributes to balance/posture; located in inner ear and sensitive to gravitational forces.

GESTALT PRINCIPLES OF PERCEPTION

  • Gestalt Psychology Basis: The whole perception is more than the sum of its parts, creating patterns/predictable structures.

  • Key principles include:

    1. Figure-Ground relationship: Differentiation between foreground and background.

    2. Proximity: Objects close together are grouped.

    3. Similarity: Similar items are grouped.

    4. Continuity: We perceive continuous patterns.

    5. Closure: We perceive shapes as whole objects even if parts are missing.

IMPLICIT BIAS AND PERCEPTION

  • Perception may not align with reality due to biases and preconceived notions.

  • The Stroop Effect illustrates reaction time differences between neutral and conflicting stimuli.

Final Note

  • Increased awareness of the interactions between perception, sensory input, biases, and expectations can enhance understanding of personal and societal interactions while forming perceptions.