Psychology Exam 2: Topic 3 - Perception

Overview of Perception

• Perception is the process of recognizing, organizing, and making sense of sensory information from the environment.

Key Concepts

• Sensation vs. Perception:
  • Sensation: initial detection of stimuli by sensory organs
  • Perception: interpretation of sensory signals by the brain
• Inverse Problem: the challenge of perceiving the world accurately based on incomplete or ambiguous sensory information

Examples Illustrating Perception Challenges

• Not Perceiving What Is There: failing to recognize obvious objects (e.g., camouflaged animal)
• Perceiving What Is Not There: creating perceptions of objects or shapes that do not exist (e.g., illusory contours like a triangle)
• Perceiving What Cannot Be There: presenting impossible objects (e.g., perpetual staircase)
• Competing Perceptions: different interpretations of the same stimulus leading to competing perceptions (e.g., optical illusions like the spinning dancer)

Importance of Perception

• Understanding perception is essential for interacting with the environment and achieving goals
• Perception helps solve the inverse problem, creating accurate representations of the external world from sensory inputs

Sources of Information for Perception

• Genes: information passed down through evolution
• Past Experience: learned information throughout an individual's life
• Internal State: current physiological or emotional state
• Environmental Context: immediate surroundings and conditions
• Proximal Stimulus: direct sensory input from the environment

Sensory Systems

Key Components

• Distal Stimulus: the actual object or event in the world
• Proximal Stimulus: the sensory input received by sensory organs
• Sensory Receptors: specialized cells that convert external stimuli into neural signals
• Neural Pathway: routes from sensory receptors to the brain
• Hierarchy of Cortical Areas: different brain areas that process sensory information
• Percept: the mental representation of the distal stimulus

The Visual System

Eye Anatomy and Function

• Blindspot: area on the retina without photoreceptors where the optic nerve exits the eye
• Retina: layer of photoreceptors (rods and cones) that detect light
• Photoreceptors:
  • Rods: sensitive to low light levels; do not detect color
  • Cones: detect color; concentrated in the fovea for detailed vision
• Primary Visual Pathway:
  • Visual fields are processed in the opposite hemispheres of the brain
  • Pathway: from ganglion cells in the retina, through the LGN (thalamus), to the primary visual cortex (V1)
  • Topographic Mapping in V1: each part of the visual field is represented in a specific location in V1

The Auditory System

Ear Anatomy and Function

• Sound: changes in air pressure that the ear converts into neural signals
• Ear Drum (Tympanum): converts air pressure changes into mechanical vibrations
• Cochlea: contains hair cells that detect vibrations and convert them into neural signals
• Hair Cells:
  • Located on the basilar membrane; different parts respond to different frequencies
• Primary Auditory Pathway:
  • Pathway: from the auditory nerve, through various brainstem nuclei, to the medial geniculate nucleus (thalamus), and then to the primary auditory cortex

The Somatosensory System

Types of Sensation

• Mechanoreception: detects pressure, vibration, and distortion
• Thermoception: detects temperature changes
• Nociception: detects harmful stimuli
• Proprioception: detects body position and movement