Sensation and Perception

Sensation and Perception

• All knowledge originates from perceptions.
• Sensation involves detecting, converting, and transmitting raw sensory information from sense receptors to the brain.
• Sense organs include eyes, ears, nose, tongue, skin, and internal organs.
• Perception is assembling and combining sensory input into meaningful patterns in the brain.
• Psychophysics studies the relationship between physical stimuli and sensations.
• Examples of physical stimuli include light (brightness, color), sound (volume, pitch), pressure (weight), and taste (sweetness, saltiness).
• Transduction converts physical energy into neural signals.
• Sensory receptors convert physical energy into nerve impulses.

Sensation Thresholds

• Absolute threshold: Minimum stimulation needed to detect a stimulus 50% of the time.
• Just Noticeable Difference (JND): Minimum difference between two stimuli detectable 50% of the time.
• Weber's Law: JND is a constant proportion of the original stimulus intensity; a certain percentage, not an amount, of change.
• Signal Detection Theory: Predicts detection of a stimulus amidst background noise. Detection varies among individuals.

Somesthetic Senses

• Vestibular sense: Balance and body position in space.
• Kinesthetic sense: Body position and movement of body parts.
• Somatosensory touch (pressure, warmth, cold, pain)

Body Position and Movement

• Kinesthesis: Sensation of body part position and movement.
• Vestibular sense: Body position relative to gravity, and sense of balance.
• Semicircular canals (in ears): Filled with fluid that responds to head movements.
• Motion sickness: Vestibular system sensations mismatch with other senses.

Vision and Hearing

• Auditory system transduces rhythmic movement of air molecules into neural impulses.
• Sound waves: Oscillation of pressured transmitted through materials. Frequency and amplitude influence pitch and loudness.
• Sound localization: Sound heard first and loudest in the nearest ear.

Factors influencing Perception

• Selective vs. divided attention: Focusing on one stimulus vs. splitting focus between tasks.
• Cocktail party effect: Ability to attend to one conversation amongst others (figure-ground).
• Inattentional blindness (perceptual blindness): Failure to perceive things while attending to other stimuli.
• Perceptual constancies: Perceiving objects as constant despite changes in retinal images (color, size, shape).

Depth Perception

• Depth perception: Ability to judge distance and see in 3-dimensions.
• Visual Cliff (Gibson): Depth perception study using infants.

Depth Cues

• Monocular depth cues: Clues to distance using one eye.

• Accommodation: Lens bending to focus on differing distances.

• Pictorial depth cues: Cues in the image for space, depth, and distance.

  • Linear perspective: Parallel lines converging in the distance.
  • Relative size: Larger object appears closer.
  • Relative height: Higher object appears farther.
  • Light and shadow: Light assumed to come from above.
  • Interposition: Nearest object obscuring distant objects.
  • Texture gradients: Closer objects have more detail.

• Binocular depth cues: Clues using two eyes.

• Convergence: Eyes turning towards objects to see distances under 50 ft.

• Retinal disparity: Two eyes see two images; disparity difference signals depth.

Perceptual Processing

• Perceptual expectations (perceptual set): Prior learning guides perception.

• Top-down processing: Processing influenced by expectations and knowledge. Information starts from high-level processes and moves down.

• Bottom-up processing: Processing based on stimulus features. Information starts from sensory data and moves up.

• Parallel processing: Simultaneous processing of several stimuli at once.

• Perceptual adaptation: Ability to adjust to altered viewing fields.

Explore the fundamental concepts of sensation and perception in psychology. This quiz covers key topics such as sensory organs, transduction, and thresholds. Test your understanding of how we detect and interpret sensory information.