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

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Signal Detection Theory (SDT)

Signal Detection Theory explains how individuals differentiate meaningful stimuli (signals) from background noise in ambiguous conditions. Originating from radar research, SDT has been adopted in psychology to explore perceptual decision-making.

Signal vs. noise

  • Signal: The specific target an individual tries to detect.
  • Noise: All additional, irrelevant stimuli that may obscure the signal.

Detection outcomes

  • Hit: Correct identification of a present signal.

  • Miss: Failure to detect an existing signal.

  • False alarm: Belief in a signal when none is present.

  • Correct rejection: Accurate perception that no signal is present.

Sensitivity (d′)

  • Represents how effectively someone can tell signal apart from noise; greater d′ means better discrimination.

Criterion (β)

  • The subjective threshold a person sets to decide if a signal is present, shaped by bias, expectations, or cost-benefit considerations.

Applications

  • Perception studies: Understanding detection of visual or auditory stimuli under varying conditions.
  • Memory research: Distinguishing between old (familiar) and new (unfamiliar) information.
  • Decision-making: Exploring how uncertainty impacts judgments, given both sensory ability and personal criteria.

Influencing factors

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

Sensory adaptation

Sensory adaptation (or neural adaptation) describes the gradual reduction in responsiveness to a constant stimulus, enabling organisms to redirect their attention to changing inputs in the environment.

Mechanisms

  • Neural response reduction: Continuous exposure decreases receptor response.
  • Efficient encoding: The sensory system recalibrates to emphasize new or dynamic 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 initially noticeable, then fades.

Distinction from habituation

  • Sensory Adaptation: A physiological change at the receptor level.
  • Habituation: A psychological process reducing behavioral response without necessarily altering sensory receptor function.

Functional Importance

  • By ignoring static, unimportant stimuli, organisms conserve resources and remain primed to detect new events or potential threats, enhancing survival.

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