Sensation and Perception: An Overview

Sensation and Perception

• Sensation and perception are key elements in memory processes.
• Processes of sensation involve reception, transduction, and transmission.
• Processes of perception involve selection, organization, and interpretation.
• The role of attention in memory includes selective and divided attention.
• The Cocktail party effect (Cherry, 1953) demonstrates selective and divided attention.

Understanding Senses

• For a sensation to occur, appropriate stimulus energy must reach the sense organ.
• The stimulus needs to be at a sufficient level to activate the sense receptors.
• The strength of the stimulus must reach the absolute threshold for sensation.
• Absolute threshold is the minimum energy level needed for external stimuli to be detected by internal senses.
• Absolute threshold depends on environmental factors like noise and light levels.
• Absolute threshold depends on psychological factors like fatigue, motivation, stress, and expectations.

Threshold Examples of Senses

• Touch: Feeling a bee's wing falling a distance of 1 cm onto the skin.
• Hearing: Hearing a clock ticking 20 feet away.
• Sight: Seeing a candle flame 30 miles away on a clear night.
• Smell: Smelling a single drop of perfume in a three-room house.
• Taste: Tasting a single teaspoon of sugar dissolved in two gallons of water.

Sensation vs. Perception

• Sensation is the process where sensory organs detect stimuli and transmit information to the brain.
• Sensation is a physiological process.
• Perception is the mental process of receiving, organizing, and interpreting sensory information into meaningful events.
• Perception is a psychological process.
• Sensation and perception work together.

Visual Perception

• Visual perception involves consistent instructions enabling organization and interpretation of visual information.
• Visual perception helps the brain:
  • Group information into a recognizable whole.
  • Identify an object's size, shape, and orientation.
  • Determine object depth and distance.
• Sensory perspective involves the physiological structures and processes.
• Psychological perspective involves cognitive processes.

Steps from Sensation to Perception

• Reception: Stimulus energy is collected by the eye.
• Transduction: Stimulus energy is converted into electrochemical nerve impulses.
• Transmission: Receptor cells send nerve impulses to the primary sensory cortex.
• Selection: Important stimuli are selected for attention.
• Organization: Information is organized in the brain.
• Interpretation: Past experiences, motives, values, and context give the stimulus its meaning.

Process of Sensation

• Reception: Light is taken in by the eye and focused on the retina.
• Reception: Rods and cones detect light energy.
• Transduction: Photoreceptors change electromagnetic energy (light) into electrochemical energy (signals).
• Transmission: Information is sent as electrical impulses along the optic nerve to the visual cortex at the back of the brain.

Process of Perception

• Bottom-up processing starts with sensory input and builds perception from details.
• Bottom-up processing relies on data, not assumptions.
• Top-down processing is guided by knowledge and expectations.
• Top-down processing influences the interpretation of sensory data and enables quick responses.

Selection

• The brain filters stimuli and selects important features while ignoring unimportant ones.
• Feature detector cells respond to specific perceptual features like lines, shapes, edges, spots, or colors.

Organisation

• Involves reassembling visual information elements into meaningfulness using perception principles.
• Organisation groups selected stimuli features to perceive a whole.
• Prior experiences influence this.
• A "house" is seen as a whole, rather than its individual components.

Interpretation

• The process assigns sensory information, creating understanding of what it actually represents Influenced by expectations, motivation and experiences from the past.
• Multiple interpretations are possible.

Consciousness

• Consciousness is awareness of thoughts, feelings, perceptions, and surroundings.
• The level of consciousness (awareness) of internal/external events varies.
• Different states of consciousness are experienced throughout a day.
• States of consciousness exist on a continuum without distinct boundaries.

Consciousness Continuum

• Ranges range from high to low levels of awareness
• Starts with selective/focused attention
• Divided attention is next, dropping down to daydreaming state, meditation, hypnosis, light sleep, deep sleep
• Then anesthetized and finally unconscious

Attention

• Attention involves actively processing information consciously or unconsciously.
• Attention overlaps with consciousness, and is often what one is consciously ware of.
• Attention will be attracted by
  • New or unusual stimuli
  • Changes in stimulation
  • Something personally
  • Something that is important for us to attend to

Selective Attention

• Selective attention is the ability to focus on specific stimuli or objects in the environment filtering out distractions.

Selective Inattention

• Selective inattention involves attending to/avoiding information that may be relevant but emotionally upsetting.

Divided Attention

• Divided attention is the ability to focus on multiple stimuli simultaneously.

Cocktail Party Effect (Cherry, 1953)

• Individuals can focus on one voice in a noisy room.
• Cherry indicated that this ability depended on physical differences like a speaker’s voice, intensity, and location.
• Listeners hearing two same-voice messages simultaneously found it hard to separate based on meaning alone.
• Multiple messages heard at once impairs the recall all of the auditory information.
• Selective attending will take place for pieces of information that catch attention.

Cocktail Party Effect Studies

• Participants shadowed an auditory message while another message was played in the other ear.
• Very little information was extracted from the second message.
• Participants did not notice if the message was in a foreign language or played in reverse.
• Unattended auditory information is not thoroughly processed and has little memory.

Explore the fundamentals of sensation and perception, vital components of memory. This lesson explains reception, transduction, transmission, selection, organization, and interpretation. Understand absolute thresholds and the influence of environmental and psychological factors.