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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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2.1.2 Signal detection and sensory adaptation
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2. Psych/soc
2.1. Sensing the environment

Signal detection and sensory adaptation

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Signal detection theory (SDT)

Signal detection theory (SDT) explains how people decide whether a meaningful stimulus (a signal) is present when there’s also background noise and the situation is uncertain. SDT began in radar research and is widely used in psychology to study perceptual decision-making.

Signal vs. noise

  • Signal: The specific target you’re trying to detect.
  • Noise: All other, irrelevant stimuli that can mask or mimic the signal.

Detection outcomes

  • Hit: Correctly identifying a signal when it is present.
  • Miss: Failing to detect a signal that is present.
  • False alarm: Thinking a signal is present when it is not.
  • Correct rejection: Correctly deciding that no signal is present.

Sensitivity (d′)

  • Sensitivity (d′) describes how well someone can distinguish signal from noise. A larger d′ means better discrimination.

Criterion (β)

  • Criterion (β) is the decision threshold a person uses to say “signal present” versus “signal absent.” It reflects bias, expectations, and cost-benefit considerations (for example, whether misses are more costly than false alarms).

Applications

  • Perception studies: Understanding detection of visual or auditory stimuli under different conditions.
  • Memory research: Distinguishing between old (familiar) and new (unfamiliar) information.
  • Decision-making: Examining how uncertainty affects judgments, based on both sensory ability (sensitivity) and the person’s chosen threshold (criterion).

Influencing factors

  • Stimulus intensity: Stronger signals are easier to detect.
  • Environment: Background noise or distractions make detection harder.
  • Psychological state: Attention, motivation, and fatigue can change sensitivity.

Sensory adaptation

Sensory adaptation (or neural adaptation) is the gradual decrease in responsiveness to a constant stimulus. This shift helps organisms focus less on unchanging input and more on changes in the environment.

Mechanisms

  • Neural response reduction: With continuous exposure, receptors respond less strongly.
  • Efficient encoding: The sensory system recalibrates to emphasize new or changing stimuli.

Examples

  • Olfactory adaptation: A strong odor becomes less noticeable over time.
  • Visual adaptation: Eyes adjust when moving from bright light into darkness.
  • Tactile adaptation: Wearing a watch or ring is noticeable at first, then fades from awareness.

Distinction from habituation

  • Sensory adaptation: A physiological change at the receptor level.
  • Habituation: A psychological process that reduces behavioral responding without necessarily changing sensory receptor function.

Functional importance

  • By reducing attention to constant, unimportant stimuli, organisms conserve resources and stay ready to notice new events or potential threats.

Signal detection theory (SDT)

  • Explains detection of signals amid background noise and uncertainty
  • Four outcomes: hit, miss, false alarm, correct rejection
  • Sensitivity (d′): ability to distinguish signal from noise
  • Criterion (β): decision threshold; reflects bias and cost-benefit analysis

Applications of SDT

  • Used in perception, memory, and decision-making research
  • Analyzes effects of uncertainty, sensitivity, and criterion on judgments

Influencing factors in SDT

  • Stimulus intensity: stronger signals easier to detect
  • Environment: more noise/distraction reduces detection accuracy
  • Psychological state: attention, motivation, fatigue affect sensitivity

Sensory adaptation

  • Gradual decrease in response to constant stimulus
  • Mechanisms:
    • Neural response reduction at receptor level
    • Efficient encoding of new or changing stimuli

Examples of sensory adaptation

  • Olfactory: odors become less noticeable over time
  • Visual: eyes adjust to changes in light
  • Tactile: sensation of wearing jewelry fades

Distinction from habituation

  • Sensory adaptation: physiological, receptor-level change
  • Habituation: psychological, reduced behavioral response

Functional importance of adaptation

  • Conserves attention/resources for new or important stimuli
  • Enhances detection of environmental changes or threats

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Signal detection and sensory adaptation

Signal detection theory (SDT)

Signal detection theory (SDT) explains how people decide whether a meaningful stimulus (a signal) is present when there’s also background noise and the situation is uncertain. SDT began in radar research and is widely used in psychology to study perceptual decision-making.

Signal vs. noise

  • Signal: The specific target you’re trying to detect.
  • Noise: All other, irrelevant stimuli that can mask or mimic the signal.

Detection outcomes

  • Hit: Correctly identifying a signal when it is present.
  • Miss: Failing to detect a signal that is present.
  • False alarm: Thinking a signal is present when it is not.
  • Correct rejection: Correctly deciding that no signal is present.

Sensitivity (d′)

  • Sensitivity (d′) describes how well someone can distinguish signal from noise. A larger d′ means better discrimination.

Criterion (β)

  • Criterion (β) is the decision threshold a person uses to say “signal present” versus “signal absent.” It reflects bias, expectations, and cost-benefit considerations (for example, whether misses are more costly than false alarms).

Applications

  • Perception studies: Understanding detection of visual or auditory stimuli under different conditions.
  • Memory research: Distinguishing between old (familiar) and new (unfamiliar) information.
  • Decision-making: Examining how uncertainty affects judgments, based on both sensory ability (sensitivity) and the person’s chosen threshold (criterion).

Influencing factors

  • Stimulus intensity: Stronger signals are easier to detect.
  • Environment: Background noise or distractions make detection harder.
  • Psychological state: Attention, motivation, and fatigue can change sensitivity.

Sensory adaptation

Sensory adaptation (or neural adaptation) is the gradual decrease in responsiveness to a constant stimulus. This shift helps organisms focus less on unchanging input and more on changes in the environment.

Mechanisms

  • Neural response reduction: With continuous exposure, receptors respond less strongly.
  • Efficient encoding: The sensory system recalibrates to emphasize new or changing stimuli.

Examples

  • Olfactory adaptation: A strong odor becomes less noticeable over time.
  • Visual adaptation: Eyes adjust when moving from bright light into darkness.
  • Tactile adaptation: Wearing a watch or ring is noticeable at first, then fades from awareness.

Distinction from habituation

  • Sensory adaptation: A physiological change at the receptor level.
  • Habituation: A psychological process that reduces behavioral responding without necessarily changing sensory receptor function.

Functional importance

  • By reducing attention to constant, unimportant stimuli, organisms conserve resources and stay ready to notice new events or potential threats.
Key points

Signal detection theory (SDT)

  • Explains detection of signals amid background noise and uncertainty
  • Four outcomes: hit, miss, false alarm, correct rejection
  • Sensitivity (d′): ability to distinguish signal from noise
  • Criterion (β): decision threshold; reflects bias and cost-benefit analysis

Applications of SDT

  • Used in perception, memory, and decision-making research
  • Analyzes effects of uncertainty, sensitivity, and criterion on judgments

Influencing factors in SDT

  • Stimulus intensity: stronger signals easier to detect
  • Environment: more noise/distraction reduces detection accuracy
  • Psychological state: attention, motivation, fatigue affect sensitivity

Sensory adaptation

  • Gradual decrease in response to constant stimulus
  • Mechanisms:
    • Neural response reduction at receptor level
    • Efficient encoding of new or changing stimuli

Examples of sensory adaptation

  • Olfactory: odors become less noticeable over time
  • Visual: eyes adjust to changes in light
  • Tactile: sensation of wearing jewelry fades

Distinction from habituation

  • Sensory adaptation: physiological, receptor-level change
  • Habituation: psychological, reduced behavioral response

Functional importance of adaptation

  • Conserves attention/resources for new or important stimuli
  • Enhances detection of environmental changes or threats