General psychology Freshman(1)

Chapter Two: Sensation & Perceptions

Overview

  • All outside information comes through our senses.

Sensation

  • Definition: The process of detecting, receiving, converting, and transmitting sensory input from receptors.

  • Function: Detects environment stimuli (e.g. light, sound).

Perception

  • Definition: The process of organizing, identifying, and interpreting sensory input into meaningful representations.

  • Relation to Memory: Involves the integration of past experiences for understanding.

Sensation vs. Perception

  • Sensation translates stimuli into neural signals; Perception processes those signals for understanding.

  • Both occur through sensory systems (e.g. vision, hearing).

  • Continuous process: Sensation feeds into perception and vice versa.

Processing Stages

  1. Input (Stimuli detection)

  2. Information-Processing (Converting stimuli into neural information)

  3. Output (Response generation)

Key Processes

  • Transduction: Conversion of stimulus into neural impulses (e.g. light into neural signals).

  • Perceptual Processes:

    • Selection: Choosing which stimuli to process.

    • Organization: Structuring information into patterns.

    • Interpretation: Understanding those patterns based on experience.

Basic Functions

  • Detection: Sensation detects sensory stimuli.

  • Interpretation: Perception gives meaning to the stimuli.

Transduction in Different Senses

  • Vision: Light waves -> Neural impulses

  • Hearing: Sound waves -> Neural impulses

  • Taste/Smell: Chemical reactions -> Neural impulses

  • Touch: Pressure, pain, temperature -> Neural impulses

Sensory Thresholds

  • Absolute Threshold: Minimum stimulus required for detection 50% of the time.

    • Examples:

      • Sight: Candle flame 30 miles away

      • Hearing: Watch ticking 20 feet away

      • Touch: Bee's wing on cheek from 1 cm

  • Difference Threshold: Smallest detectable change in a stimulus (known as "just noticeable difference").

Laws of Perception

  • Law of Proximity: Objects close together are perceived as one group.

  • Law of Similarity: Similar items are grouped together based on visual characteristics.

  • Law of Good Continuation: Perceptions follow smooth continuous paths.

  • Law of Closure: We fill missing information to perceive complete objects.

  • Law of Pragnanz: Objects are perceived in their simplest forms.

Perceptual Constancy

  • Shape Constancy: Objects are perceived as stable shape despite changes in perspective.

  • Size Constancy: Perception of size remains constant even when images change due to distance.

  • Lightness Constancy: Perception of constant color/brightness despite different lighting conditions.

Depth and Distance Perception

  • Binocular Cues: Retinal disparity and convergence used for depth perception.

  • Monocular Cues: Size cues, linear perspective, texture gradient, atmospheric perspective, and overlap assist in judging distance.