Chapter 5: Sensation & Perception Psychology Study Guide

Sensation versus Perception

• Sensation: The process by which sensory receptors and specialized neurons detect stimuli from the environment.

• Transduction: The conversion of sensory information into neural signals that can travel through neurons and be processed by the nervous system.

• Perception: The way sensory information is organized, interpreted, and consciously experienced.

• Distinction: Sensation represents physical detection, whereas perception represents psychological interpretation.

The Five Main Senses

• Vision: Seeing.

• Hearing (audition): Detecting and interpreting sound.

• Smell (olfaction): Detecting odors.

• Taste (gustation): Detecting tastes.

• Touch (somatosensation): Detecting information such as pressure and temperature through the body.

Additional Sensory Systems

• Vestibular sense: Balance and awareness of body position and movement.

• Nociception: Detection of pain.

• Proprioception: Awareness of body position.

• Kinesthesia: Awareness of body movement.

• Thermoception: Detection of temperature.

Thresholds and Stimulus Detection

• Absolute threshold: The minimum amount of stimulus energy needed for a stimulus to be detected $50\%$ of the time.

  • Example: Hearing a clock ticking during an exam when focused on it.

• Subliminal message: A message presented below the absolute threshold, so it is not consciously noticed.

• Just Noticeable Difference (JND) / Difference threshold: The minimum difference in stimulation required to detect a difference between two stimuli.

  • Example: Noticing a difference in brightness in a dark movie theater when someone pulls out their phone.

• Signal detection theory: The ability to detect a stimulus when it is embedded in a distracting background. What an individual is looking or listening for can affect detection.

Attention

• Inattentional blindness: Failing to notice something that is completely visible because attention is focused on something else.

• Key Concept: An individual can see something without consciously noticing it if their attention is directed elsewhere.

Sensory Adaptation

• Sensory adaptation: Reduced perception of a stimulus that remains relatively constant over a prolonged period of time.

• Key Concept: Constant stimuli tend to become less noticeable over time.

Information Processing Pathways

• Bottom-up processing: Begins with basic sensory information and builds toward a complete perception (starting from the beginning).

• Top-down processing: Uses prior knowledge, experiences, expectations, and context to interpret sensory information (using existing knowledge).

• Memory Trick:

  • BOTTOM-UP = Build it from the basics.

  • TOP-DOWN = Use what you already know.

Light and Vision

• Visible spectrum: The portion of the electromagnetic spectrum that humans can see.

• Wavelength: The distance between successive wave peaks; different wavelengths of visible light are perceived as different colors.

• ROYGBIV: Red, Orange, Yellow, Green, Blue, Indigo, Violet.

• Trichromatic theory: Color vision depends on three types of cones in the retina that are most sensitive to red, green, and blue wavelengths.

• Color blindness: Reduced or altered ability to distinguish certain colors, often involving red-green color discrimination; it is more common in males than females.

Sound and Hearing

• Frequency: The number of wave cycles per second; frequency is related to pitch.

  • Low frequency: Corresponds to low pitch.

  • High frequency: Corresponds to high pitch.

• Decibels ($\text{dB}$): A logarithmic unit used to measure sound intensity and loudness.

• Human hearing range: Approximately $20\,\text{Hz}$ to $20,000\,\text{Hz}$ ($20\,\text{kHz}$), although individual limits vary.

• Normal conversation level: Approximately $60\,\text{dB}$.