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Introduction
1. CARS
2. Psych/soc
2.1 Sensing the environment
2.1.1 Sensory perception
2.1.2 Signal detection and sensory adaptation
2.1.3 Psychophysics and receptors
2.1.4 Sensory pathways and sleep physiology
2.1.5 Touch/somatosensation
2.1.6 Vision
2.1.7 Hearing
2.1.8 Gustation
2.1.9 Olfactory, kinesthesia and vestibular
2.2 Making sense of the environment
2.3 Responding to the world
2.4 Individual influences on behavior
2.5 Social processes and human behavior
2.6 Attitude and behavior change
2.7 Self-identity
2.8 Psych/soc factors affecting interaction and perception
2.9 Elements of social interaction
2.10 Understanding social structure
2.11 Demographic characteristics and processes
2.12 Social inequality
3. Bio/biochem
4. Chem/phys
Wrapping up
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2.1.3 Psychophysics and receptors
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2. Psych/soc
2.1. Sensing the environment

Psychophysics and receptors

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Psychophysics

Psychophysics is a field that quantitatively examines how physical stimuli relate to the sensations and perceptions they evoke. By measuring detection thresholds and discrimination abilities, psychophysics helps connect the external world (the stimulus) to internal experience (what you perceive).

Methods in psychophysics:

  • Method of limits: Gradually increase or decrease stimulus intensity to find the point at which it becomes just detectable.

  • Method of adjustment: Participants adjust the stimulus themselves until it reaches the threshold.

  • Method of constant stimuli: Stimuli of different intensities are presented in random order to determine the detection threshold.

Applications

Sensory research: Enables the study of thresholds, leading to improved tools like hearing aids.

Ergonomics and design: Helps ensure devices align with human sensory limits.

Neuroscience: Aids in investigating sensory processing pathways and perceptual disorders.

Sensory receptors

Sensory receptors convert external stimuli into neural signals. Each receptor type is specialized for particular stimulus modalities.

Electromagnetic receptors

  • Photoreceptors (rods and cones): Detect light in the retina.

  • Thermoreceptors: Adapt slowly to temperature changes, with distinct “cold” and “warm” ranges.

  • Mechanoreceptors:

    Function: Activated by pressure or pressure changes (e.g., hearing, touch, balance).

    Adaptation rates: Very rapidly adapting (detect changes in velocity) or slowly adapting (detect intensity/duration).

    Types:

    • Pacinian Corpuscles: Deep dermis or subcutaneous tissue; very rapid adaptation for vibration/deep pressure.
    • Meissner’s Corpuscles: In the papillary dermis of non-hairy skin; rapid adaptation for two-point discrimination, light touch, low-frequency vibrations.
    • Merkel’s Discs/Tactile Discs: Slowly adapting; found in non-hairy skin (dermal-epidermal junction) and mucosal membranes; detect low-frequency vibrations and vertical indentations.
    • Ruffini’s Corpuscles: In dermis and joint capsules; sense stretch and joint rotation.

Chemoreceptors

  • Function: Detect chemical stimuli.
  • Examples: Olfactory receptors for smell, gustatory receptors for taste, oxygen sensors in carotid/aortic bodies, pH sensors in the medulla.

Nociceptors

  • Function: Respond to harmful stimuli that can damage tissue (extreme temperatures, high pressure, etc.).
  • Types:
    • Thermal/mechanical (A-delta fibers): Myelinated; fast-conducting; activated by sharp pain or high pressure.
    • Polymodal (C Fibers): Unmyelinated; slower; respond to mechanical, chemical, and extreme temperature stimuli.
    • TRP ion channels: Activated by noxious stimuli.
    • Inflammatory mediators: Histamine, bradykinin, prostaglandins, etc., can directly or indirectly trigger nociceptors, leading to pain and heightened sensitivity.
    • Neurotransmitters: Glutamate, substance P, calcitonin, and somatostatin are commonly released during pain signaling.

Psychophysics

  • Quantifies relationship between physical stimuli and perception
  • Key methods:
    • Method of limits: gradual intensity change to find threshold
    • Method of adjustment: participant sets threshold
    • Method of constant stimuli: random order, various intensities
  • Applications: sensory research, ergonomics/design, neuroscience

Sensory receptors

  • Convert external stimuli into neural signals
  • Specialized by stimulus modality (light, temperature, pressure, chemicals, pain)

Electromagnetic receptors

  • Photoreceptors (rods/cones): detect light (retina)
  • Thermoreceptors: slow adaptation; detect temperature (cold/warm ranges)
  • Mechanoreceptors: sense pressure, touch, vibration, stretch
    • Pacinian corpuscles: deep, rapid adaptation, vibration/deep pressure
    • Meissner’s corpuscles: superficial, rapid adaptation, light touch, two-point discrimination
    • Merkel’s discs: slow adaptation, low-frequency vibration, indentation
    • Ruffini’s corpuscles: stretch, joint rotation

Chemoreceptors

  • Detect chemical stimuli
  • Examples: olfactory (smell), gustatory (taste), O₂/pH sensors

Nociceptors

  • Respond to damaging/harmful stimuli (pain)
  • Types:
    • A-delta fibers: myelinated, fast, sharp pain/high pressure
    • C fibers: unmyelinated, slow, polymodal (mechanical, chemical, temperature)
    • TRP ion channels: activated by noxious stimuli
  • Modulated by inflammatory mediators (histamine, bradykinin, prostaglandins) and neurotransmitters (glutamate, substance P, calcitonin, somatostatin)

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Psychophysics and receptors

Psychophysics

Psychophysics is a field that quantitatively examines how physical stimuli relate to the sensations and perceptions they evoke. By measuring detection thresholds and discrimination abilities, psychophysics helps connect the external world (the stimulus) to internal experience (what you perceive).

Methods in psychophysics:

  • Method of limits: Gradually increase or decrease stimulus intensity to find the point at which it becomes just detectable.

  • Method of adjustment: Participants adjust the stimulus themselves until it reaches the threshold.

  • Method of constant stimuli: Stimuli of different intensities are presented in random order to determine the detection threshold.

Applications

Sensory research: Enables the study of thresholds, leading to improved tools like hearing aids.

Ergonomics and design: Helps ensure devices align with human sensory limits.

Neuroscience: Aids in investigating sensory processing pathways and perceptual disorders.

Sensory receptors

Sensory receptors convert external stimuli into neural signals. Each receptor type is specialized for particular stimulus modalities.

Electromagnetic receptors

  • Photoreceptors (rods and cones): Detect light in the retina.

  • Thermoreceptors: Adapt slowly to temperature changes, with distinct “cold” and “warm” ranges.

  • Mechanoreceptors:

    Function: Activated by pressure or pressure changes (e.g., hearing, touch, balance).

    Adaptation rates: Very rapidly adapting (detect changes in velocity) or slowly adapting (detect intensity/duration).

    Types:

    • Pacinian Corpuscles: Deep dermis or subcutaneous tissue; very rapid adaptation for vibration/deep pressure.
    • Meissner’s Corpuscles: In the papillary dermis of non-hairy skin; rapid adaptation for two-point discrimination, light touch, low-frequency vibrations.
    • Merkel’s Discs/Tactile Discs: Slowly adapting; found in non-hairy skin (dermal-epidermal junction) and mucosal membranes; detect low-frequency vibrations and vertical indentations.
    • Ruffini’s Corpuscles: In dermis and joint capsules; sense stretch and joint rotation.

Chemoreceptors

  • Function: Detect chemical stimuli.
  • Examples: Olfactory receptors for smell, gustatory receptors for taste, oxygen sensors in carotid/aortic bodies, pH sensors in the medulla.

Nociceptors

  • Function: Respond to harmful stimuli that can damage tissue (extreme temperatures, high pressure, etc.).
  • Types:
    • Thermal/mechanical (A-delta fibers): Myelinated; fast-conducting; activated by sharp pain or high pressure.
    • Polymodal (C Fibers): Unmyelinated; slower; respond to mechanical, chemical, and extreme temperature stimuli.
    • TRP ion channels: Activated by noxious stimuli.
    • Inflammatory mediators: Histamine, bradykinin, prostaglandins, etc., can directly or indirectly trigger nociceptors, leading to pain and heightened sensitivity.
    • Neurotransmitters: Glutamate, substance P, calcitonin, and somatostatin are commonly released during pain signaling.
Key points

Psychophysics

  • Quantifies relationship between physical stimuli and perception
  • Key methods:
    • Method of limits: gradual intensity change to find threshold
    • Method of adjustment: participant sets threshold
    • Method of constant stimuli: random order, various intensities
  • Applications: sensory research, ergonomics/design, neuroscience

Sensory receptors

  • Convert external stimuli into neural signals
  • Specialized by stimulus modality (light, temperature, pressure, chemicals, pain)

Electromagnetic receptors

  • Photoreceptors (rods/cones): detect light (retina)
  • Thermoreceptors: slow adaptation; detect temperature (cold/warm ranges)
  • Mechanoreceptors: sense pressure, touch, vibration, stretch
    • Pacinian corpuscles: deep, rapid adaptation, vibration/deep pressure
    • Meissner’s corpuscles: superficial, rapid adaptation, light touch, two-point discrimination
    • Merkel’s discs: slow adaptation, low-frequency vibration, indentation
    • Ruffini’s corpuscles: stretch, joint rotation

Chemoreceptors

  • Detect chemical stimuli
  • Examples: olfactory (smell), gustatory (taste), O₂/pH sensors

Nociceptors

  • Respond to damaging/harmful stimuli (pain)
  • Types:
    • A-delta fibers: myelinated, fast, sharp pain/high pressure
    • C fibers: unmyelinated, slow, polymodal (mechanical, chemical, temperature)
    • TRP ion channels: activated by noxious stimuli
  • Modulated by inflammatory mediators (histamine, bradykinin, prostaglandins) and neurotransmitters (glutamate, substance P, calcitonin, somatostatin)