Sensation
Introduced| English |
|---|
| Sensation/senˈseɪʃn/ |
| transduction/trænsˈdʌkʃn/ |
| threshold/ˈθreʃəʊld/ |
| just-noticeable difference/dʒʌst ˈnəʊtɪsəbl ˈdɪfrəns/ |
| Weber's law/ˈwebəz lɔː/ |
| Sensory adaptation/ˈsensəri ˌædæpˈteɪʃn/ |
| retina/ˈretɪnə/ |
| visual accommodation/ˈvɪʒuːəl əˌkɒməˈdeɪʃn/ |
| Rods/rɒdz/ |
| cones/kəʊnz/ |
| trichromatic theory/ˌtrɪkrəʊˈmætɪk ˈθɪəri/ |
| opponent-process theory/əˈpəʊnənt ˈprəʊses ˈθɪəri/ |
| pitch/pɪtʃ/ |
| loudness/ˈlaʊdnəs/ |
| Olfaction/ɒlˈfækʃn/ |
| gustation/ɡʌˈsteɪʃn/ |
| Gate control theory/ɡeɪt kənˈtrəʊl ˈθɪəri/ |
| vestibular sense/veˈstɪbjʊlə sens/ |
| kinesthesis/ˈkaɪnsθəsɪs/ |
You stop noticing the clock after a minute
- A sound that was obvious becomes unnoticeable while it is still there.
- Your senses are not recording devices — they report change.
- This lesson is about how the body turns physical energy into a signal, and what it discards.
Sensation and transduction
- Sensation 感觉 is detecting information from the environment that meets a certain threshold 阈限, and turning it into a neural signal.
- That conversion is transduction 换能.
- Below threshold, the stimulus is present but produces no signal at all.
Converting a physical stimulus into a neural signal is called ____.
Transduction is the conversion step; below threshold no signal is produced at all.
Detecting change, and stopping
- The just-noticeable difference 最小可觉差 is the smallest change you can detect.
- Weber's law 韦伯定律 says that difference is a proportion of the original, not a fixed amount.
- Sensory adaptation 感觉适应 is the diminished response to an unchanging stimulus — the clock you stop hearing.
Weber's law says the just-noticeable difference is...
One spoon of sugar is detectable in a cup and not in a jug — the proportion is what matters.
Sensory adaptation is not the same as habituation. Adaptation happens in the sense organ itself — the receptors stop responding. Habituation is a learned drop in response that happens in the brain. The exam distinguishes them.
Which sensory system?
Sort each structure or term into the sense it belongs to.
The CED says colour vision is explained by the trichromatic theory alone.
Colour vision is explained by both the trichromatic and the opponent-process theories.
Vision, in the terms the exam uses
- The retina 视网膜 is the photosensitive surface at the back of the eye; the lens focuses light onto it by visual accommodation 视觉调节.
- Rods 视杆细胞 in the periphery detect shape and movement but not colour; cones 视锥细胞 detect colour and detail.
- Colour vision is explained by both the trichromatic theory 三色理论 and the opponent-process theory 对立过程理论.
Select all that belong to the body senses rather than vision or hearing.
The retina is part of the visual system; the other three are body senses.
Match each term to the sense it belongs to.
Rods and cones code light, place theory codes pitch, and olfaction bypasses the thalamus.
Hearing, chemistry, touch and balance
- Sound is air movement: wavelength gives pitch 音高 and amplitude gives loudness 响度. Pitch perception is explained by place, volley and frequency theories.
- Olfaction 嗅觉 is the only sense not routed through the thalamus; gustation 味觉 has sweet, sour, salty, bitter, umami and oleogustus.
- Gate control theory 闸门控制理论 describes pain being processed in body and brain together.
- The vestibular sense 前庭觉 gives balance; kinesthesis 动觉 gives the sense of your own body's movement.
Add one spoon of sugar to a cup of tea and you taste the difference. Add one spoon to a large jug and you do not. The amount added is identical — what changed is the proportion, which is exactly what Weber's law predicts.
Sensation detects stimuli above threshold and transduces them into neural signals. The just-noticeable difference follows Weber's law as a proportion, and sensory adaptation removes unchanging stimuli. Vision uses rods and cones with two colour theories; hearing codes pitch and loudness; and vestibular and kinesthetic senses track balance and body movement.