Overview
This lecture introduces the concepts of sensation and perception, explains their differences, and covers key vocabulary terms related to how we detect and interpret information from our environment.
Sensation vs. Perception
- Sensation is the process of detecting physical energy (light, sound, touch, taste, smell) from the environment using the five senses.
- Sensation is known as bottom-up processing; it starts with raw sensory input moving towards the brain.
- Perception involves selecting, organizing, and interpreting sensory information using experiences, expectations, and motivations.
- Perception is called top-down processing; it uses prior knowledge to make sense of sensory info.
- Example: Seeing and hearing in a lecture—sensation brings in light and sound, perception interprets them as meaningful content.
Key Vocabulary Terms
- Absolute Threshold — The minimum intensity of a stimulus needed to detect it 50% of the time.
- Example: Hearing a ticking clock from a certain distance half the time.
- Signal Detection Theory — There is no single absolute threshold; detection depends on individual experiences, expectations, motivation, and fatigue.
- Subliminal Perception (Priming) — Sensing information below the absolute threshold that can unconsciously influence choices and judgments.
- Example: Subliminal messages in media or movies influencing behavior.
- Difference Threshold (Just Noticeable Difference, JND) — The smallest detectable difference between two stimuli 50% of the time.
- Example: Noticing a slight change in color, taste, or sound intensity when comparing two signals.
- Weber's Law — The JND is a constant proportion of the original stimulus; larger stimuli require a larger difference to notice a change.
Additional Concepts & Examples
- Sensory Adaptation — Reduced sensitivity after constant exposure to a stimulus (e.g., forgetting about a watch on your wrist).
- Selective Attention — Focusing conscious awareness on a specific aspect while ignoring others (e.g., cocktail party effect or Necker cube).
- Inattentional Blindness — Failing to notice obvious objects when attention is directed elsewhere (e.g., missing a gorilla in a video).
- Change Blindness — Not noticing changes in the environment due to focus on something else (e.g., not recognizing a person swap during a conversation).
- Stroop Effect — The challenge of naming the color of a word when the word itself names a different color, demonstrating limits of selective attention.
Key Terms & Definitions
- Sensation — Detection of environmental energy and encoding as neural signals (bottom-up).
- Perception — Interpretation of sensory information using mental processes (top-down).
- Absolute Threshold — Minimum stimulus level detected 50% of the time.
- Signal Detection Theory — Thresholds vary by individual factors.
- Subliminal Perception / Priming — Processing stimuli below conscious awareness.
- Difference Threshold (JND) — Minimum difference between two stimuli noticed 50% of the time.
- Weber’s Law — JND increases proportionally as stimulus magnitude increases.
- Sensory Adaptation — Diminished sensitivity to unchanging stimuli.
- Selective Attention — Focusing on certain stimuli while ignoring others.
- Inattentional Blindness — Missing obvious stimuli due to focus elsewhere.
- Change Blindness — Not noticing changes in environment.
- Stroop Effect — Interference when naming a word’s color conflicts with its meaning.
Action Items / Next Steps
- Review and memorize key vocabulary and definitions from this lecture.
- Prepare for Part Two focusing on the sensation of vision.
- Complete any assigned textbook readings or practice exercises on sensation and perception.