Cambridge IGCSE IGCSE, A-Level & AP Sheet preview

Biological Bases of Behavior

AP Psychology · Topic 1

Train
Handout Vocabulary
1.1

Nature and Nurture
Syllabus
Learning ObjectiveEssential Knowledge

1.1.A
Explain the relationship between heredity and environment in shaping behavior and mental processes.

  • 1.1.A.1 Heredity and environmental factors interact to shape behavior and mental processes.
    • 1.1.A.1.i Heredity, or “nature,” refers to genetic or predisposed characteristics that influence physical, behavioral, and mental traits and processes.
    • 1.1.A.1.ii Environmental factors, or “nurture,” refers to the external factors that one experiences, such as family interactions or education.
      • Exclusion Statement: Specific information about genetics (genotype, phenotype, DNA, chromosomes, and recessive and dominant gene expression) is beyond the scope of the AP Psychology Exam.
  • 1.1.A.2 The evolutionary perspective explores how natural selection affects the expression of behavior and mental processes to increase survival and reproductive success. Some theorists have sought to apply principles of the evolutionary perspective in ways that discriminate against others (eugenics).
  • 1.1.A.3 Research on the effects of genes on individual behavior and mental processes is often conducted using twin studies, family studies, and adoption studies.

Source: College Board AP Course and Exam Description

Psychology studies behavior 行为 (what a person does) and mental processes 心理过程 (what a person thinks and feels). Unit 1 asks where these come from in the body.

Every trait grows from two sources working together. Heredity 遗传 is what a person inherits from their parents. Environment 环境 is everything that happens around them. Neither one acts alone.

  • Nature and nurture 先天与后天 always interact. Height is inherited, but poor nutrition lowers it.
  • The evolutionary perspective 进化论视角 explains behavior that helped ancestors survive and reproduce. Fear of snakes is easy to learn because it once kept people alive.
  • Twin and adoption studies 双生子与收养研究 separate the two sources. If identical twins raised apart are still similar, heredity matters for that trait.

Note: the exam does not ask about genes, DNA, or chromosomes. It asks how heredity and environment together shape behavior.

Vocabulary Train
English Chinese Pinyin
behavior 行为 xíng wéi
mental processes 心理过程 xīn lǐ guò chéng
Heredity 遗传 yí chuán
Environment 环境 huán jìng
Nature and nurture 先天与后天 xiān tiān yǔ hòu tiān
evolutionary perspective 进化论视角 jìn huà lùn shì jiǎo
Twin and adoption studies 双生子与收养研究 shuāng shēng zi yǔ shōu yǎng yán jiū
1.2

The Nervous System
Syllabus
Learning ObjectiveEssential Knowledge

1.2.A
Differentiate among the subsystems of the human nervous system and their functions.

  • 1.2.A.1 The central nervous system includes the brain and the spinal cord and interacts with all processes in the body.
  • 1.2.A.2 The peripheral nervous system relays messages from the central nervous system to the rest of the body and includes the autonomic and somatic nervous systems.
    • 1.2.A.2.i The autonomic nervous system governs processes that are involuntary and includes the parasympathetic and sympathetic nervous systems.
    • 1.2.A.2.ii The somatic nervous system governs processes that are voluntary.

Source: College Board AP Course and Exam Description

The nervous system 神经系统 carries information around the body. It has two main parts.

The central nervous system (CNS) 中枢神经系统 is the brain and the spinal cord 脊髓. It interacts with every process in the body.

The peripheral nervous system (PNS) 周围神经系统 relays messages between the CNS and the rest of the body. It divides again:

  • The somatic nervous system 躯体神经系统 controls voluntary 随意的 movement, such as raising your hand.
  • The autonomic nervous system 自主神经系统 controls involuntary 不随意的 processes, such as heartbeat and digestion. It has two branches that work against each other: the sympathetic nervous system 交感神经系统 prepares the body for action (the "fight or flight" response), and the parasympathetic nervous system 副交感神经系统 calms the body down afterwards.
Vocabulary Train
English Chinese Pinyin
nervous system 神经系统 shén jīng xì tǒng
central nervous system (CNS) 中枢神经系统 zhōng shū shén jīng xì tǒng
spinal cord 脊髓 jí suǐ
peripheral nervous system (PNS) 周围神经系统 zhōu wéi shén jīng xì tǒng
somatic nervous system 躯体神经系统 qū tǐ shén jīng xì tǒng
voluntary 随意的 suí yì de
autonomic nervous system 自主神经系统 zì zhǔ shén jīng xì tǒng
involuntary 不随意的 bù suí yì de
sympathetic nervous system 交感神经系统 jiāo gǎn shén jīng xì tǒng
parasympathetic nervous system 副交感神经系统 fù jiāo gǎn shén jīng xì tǒng
1.3

Neurons and How They Fire
Syllabus
Learning ObjectiveEssential Knowledge

1.3.A
Explain how the structures and functions of typical neurons in the central nervous system affect behavior and mental processes.

  • 1.3.A.1 Two common types of neural cells in the brain are neurons (neural cells that transmit information) and glial cells (cells that provide structure, insulation, communication, and waste transport). These types of cells form the basis of the nervous system and are the building blocks of all behavior and mental processes.
  • 1.3.A.2 In the spinal cord, the reflex arc demonstrates how neurons within the central and peripheral nervous systems work together to respond to stimuli. Three types of neurons work together in the spinal cord to create a reflex arc: sensory neurons, motor neurons, and interneurons.

1.3.B
Explain how the basic process of neural transmission is related to behavior and mental processes.

  • 1.3.B.1 The process of neural transmission most commonly occurs in an orderly, systematic way and involves the all-or-none principle, depolarization, refractory period, resting potential, reuptake, and threshold. Disruptions to this process could lead to disorders such as multiple sclerosis or myasthenia gravis.
    • Exclusion Statement: The sodium-potassium pump is outside the scope of the AP Psychology Exam.
  • 1.3.B.2 Each neurotransmitter has specific function(s) related to behavior and mental processes, which may depend on the neurotransmitter’s location in the nervous system. Neurotransmitters generally communicate either excitatory (making an action potential more likely) or inhibitory (making an action potential less likely) messages. Neurotransmitters related to behavior and mental processes for study in AP Psychology are limited to dopamine, serotonin, norepinephrine, glutamate, GABA, endorphins, substance p, and acetylcholine.
    • Exclusion Statement: The AP Psychology Exam will only address the listed neurotransmitters in EK 1.3.B.2.
  • 1.3.B.3 Outside of the nervous system, hormones perform actions similar to neurotransmitters. Hormones related to behavior and mental processes for study in AP Psychology are limited to adrenaline, leptin, ghrelin, melatonin, and oxytocin.
    • Exclusion Statement: The AP Psychology Exam will only address the listed hormones in EK 1.3.B.3.
    • Exclusion Statement: Specific information about the glands of the endocrine system (with the exception of the pituitary gland as referenced in EK 1.4.A.4) is outside the scope of the AP Psychology Exam.

1.3.C
Explain how psychoactive drugs affect behavior and mental processes.

  • 1.3.C.1 Psychoactive drugs can influence neurotransmitter function in various ways throughout the neural communication process. Some act as agonists which encourage neural firing. Some act as antagonists which discourage neural firing. Some act as reuptake inhibitors which block the reabsorption of neurotransmitters back into the cell.
  • 1.3.C.2 Psychoactive drugs have psychological and physiological effects.
    • 1.3.C.2.i Stimulants, such as caffeine and cocaine, typically cause increased neural activity.
    • 1.3.C.2.ii Depressants, such as alcohol, typically cause decreased neural activity.
    • 1.3.C.2.iii Hallucinogens, such as marijuana, typically cause distortions in perception and/or cognition.
    • 1.3.C.2.iv Opioids, such as heroin, typically act as pain relievers.
  • 1.3.C.3 Psychoactive drug use can lead to tolerance and/or addiction. Addiction can create significant withdrawal symptoms if the psychoactive drugs are no longer consumed.

Source: College Board AP Course and Exam Description

Labelled diagram of a neuron: dendrites receive signals, the cell body integrates them, and the axon carries the impulse to the terminals
A neuron receives at the dendrites, fires along the axon, and passes the message across the synapse

Two kinds of cell do the work. Neurons 神经元 transmit information. Glial cells 神经胶质细胞 provide structure, insulation, communication, and waste transport. Together they are the building blocks of all behavior and mental processes.

A neuron has dendrites 树突 that receive signals, a cell body 细胞体, and an axon 轴突 that carries the signal away. Many axons are wrapped in a myelin sheath 髓鞘, which speeds the signal up.

Neural transmission follows a set order:

  • At rest the neuron holds a resting potential 静息电位, ready but not firing.
  • If incoming signals pass the threshold 阈限, the neuron depolarizes 去极化 and fires.
  • Firing follows the all-or-none principle 全或无原则: the neuron fires at full strength or not at all. A stronger stimulus makes it fire more often, not harder.
  • Straight after firing there is a refractory period 不应期 when the neuron cannot fire again.
  • At the synapse 突触, the gap between neurons, chemicals cross to the next cell. Leftover chemicals are taken back in a process called reuptake 再摄取.

Damage to this process can cause disorders such as multiple sclerosis 多发性硬化 or myasthenia gravis 重症肌无力.

In the spinal cord, the reflex arc 反射弧 shows the system working as a unit. Sensory neurons 感觉神经元 carry information in, interneurons 中间神经元 connect inside the cord, and motor neurons 运动神经元 carry the command out - all before the brain is involved.

Vocabulary Train
English Chinese Pinyin
Neurons 神经元 shén jīng yuán
Glial cells 神经胶质细胞 shén jīng jiāo zhì xì bāo
dendrites 树突 shù tū
cell body 细胞体 xì bāo tǐ
axon 轴突 zhóu tū
myelin sheath 髓鞘 suǐ qiào
resting potential 静息电位 jìng xī diàn wèi
threshold 阈限 yù xiàn
depolarizes 去极化 qù jí huà
all-or-none principle 全或无原则 quán huò wú yuán zé
refractory period 不应期 bù yīng qī
synapse 突触 tū chù
reuptake 再摄取 zài shè qǔ
multiple sclerosis 多发性硬化 duō fā xìng yìng huà
myasthenia gravis 重症肌无力 zhòng zhèng jī wú lì
reflex arc 反射弧 fǎn shè hú
Sensory neurons 感觉神经元 gǎn jué shén jīng yuán
interneurons 中间神经元 zhōng jiān shén jīng yuán
motor neurons 运动神经元 yùn dòng shén jīng yuán
1.3

Neurotransmitters, Hormones, and Drugs
Syllabus
Learning ObjectiveEssential Knowledge

1.3.A
Explain how the structures and functions of typical neurons in the central nervous system affect behavior and mental processes.

  • 1.3.A.1 Two common types of neural cells in the brain are neurons (neural cells that transmit information) and glial cells (cells that provide structure, insulation, communication, and waste transport). These types of cells form the basis of the nervous system and are the building blocks of all behavior and mental processes.
  • 1.3.A.2 In the spinal cord, the reflex arc demonstrates how neurons within the central and peripheral nervous systems work together to respond to stimuli. Three types of neurons work together in the spinal cord to create a reflex arc: sensory neurons, motor neurons, and interneurons.

1.3.B
Explain how the basic process of neural transmission is related to behavior and mental processes.

  • 1.3.B.1 The process of neural transmission most commonly occurs in an orderly, systematic way and involves the all-or-none principle, depolarization, refractory period, resting potential, reuptake, and threshold. Disruptions to this process could lead to disorders such as multiple sclerosis or myasthenia gravis.
    • Exclusion Statement: The sodium-potassium pump is outside the scope of the AP Psychology Exam.
  • 1.3.B.2 Each neurotransmitter has specific function(s) related to behavior and mental processes, which may depend on the neurotransmitter’s location in the nervous system. Neurotransmitters generally communicate either excitatory (making an action potential more likely) or inhibitory (making an action potential less likely) messages. Neurotransmitters related to behavior and mental processes for study in AP Psychology are limited to dopamine, serotonin, norepinephrine, glutamate, GABA, endorphins, substance p, and acetylcholine.
    • Exclusion Statement: The AP Psychology Exam will only address the listed neurotransmitters in EK 1.3.B.2.
  • 1.3.B.3 Outside of the nervous system, hormones perform actions similar to neurotransmitters. Hormones related to behavior and mental processes for study in AP Psychology are limited to adrenaline, leptin, ghrelin, melatonin, and oxytocin.
    • Exclusion Statement: The AP Psychology Exam will only address the listed hormones in EK 1.3.B.3.
    • Exclusion Statement: Specific information about the glands of the endocrine system (with the exception of the pituitary gland as referenced in EK 1.4.A.4) is outside the scope of the AP Psychology Exam.

1.3.C
Explain how psychoactive drugs affect behavior and mental processes.

  • 1.3.C.1 Psychoactive drugs can influence neurotransmitter function in various ways throughout the neural communication process. Some act as agonists which encourage neural firing. Some act as antagonists which discourage neural firing. Some act as reuptake inhibitors which block the reabsorption of neurotransmitters back into the cell.
  • 1.3.C.2 Psychoactive drugs have psychological and physiological effects.
    • 1.3.C.2.i Stimulants, such as caffeine and cocaine, typically cause increased neural activity.
    • 1.3.C.2.ii Depressants, such as alcohol, typically cause decreased neural activity.
    • 1.3.C.2.iii Hallucinogens, such as marijuana, typically cause distortions in perception and/or cognition.
    • 1.3.C.2.iv Opioids, such as heroin, typically act as pain relievers.
  • 1.3.C.3 Psychoactive drug use can lead to tolerance and/or addiction. Addiction can create significant withdrawal symptoms if the psychoactive drugs are no longer consumed.

Source: College Board AP Course and Exam Description

Neurotransmitters 神经递质 are the chemicals that cross the synapse. Each has its own job, and the effect can depend on where in the nervous system it acts. A message is either excitatory 兴奋性的 (making firing more likely) or inhibitory 抑制性的 (making firing less likely).

Only these are examinable: dopamine 多巴胺 (reward and movement), serotonin 血清素 (mood and sleep), norepinephrine 去甲肾上腺素 (alertness), glutamate 谷氨酸 (the main excitatory transmitter), GABA γ-氨基丁酸 (the main inhibitory transmitter), endorphins 内啡肽 (pain relief), substance P P物质 (pain signalling), and acetylcholine 乙酰胆碱 (muscle movement and memory).

Hormones 激素 act outside the nervous system but do a similar job, travelling more slowly through the blood. Again only five are examinable: adrenaline 肾上腺素, leptin 瘦素 (reduces hunger), ghrelin 胃饥饿素 (increases hunger), melatonin 褪黑素 (sleep), and oxytocin 催产素 (bonding).

Psychoactive drugs 精神药物 change behavior by acting on neurotransmission in three ways:

  • An agonist 激动剂 encourages neural firing.
  • An antagonist 拮抗剂 discourages it.
  • A reuptake inhibitor 再摄取抑制剂 blocks reabsorption, leaving more transmitter in the synapse.

Drug categories: stimulants 兴奋剂 (caffeine, cocaine) increase neural activity; depressants 抑制剂 (alcohol) decrease it; hallucinogens 致幻剂 (marijuana) distort perception; opioids 阿片类药物 (heroin) relieve pain. Repeated use can lead to tolerance 耐受性, where more is needed for the same effect, and to addiction 成瘾, with withdrawal 戒断反应 symptoms when use stops.

Vocabulary Train
English Chinese Pinyin
Neurotransmitters 神经递质 shén jīng dì zhì
excitatory 兴奋性的 xīng fèn xìng de
inhibitory 抑制性的 yì zhì xìng de
dopamine 多巴胺 duō bā àn
serotonin 血清素 xuè qīng sù
norepinephrine 去甲肾上腺素 qù jiǎ shèn shàng xiàn sù
glutamate 谷氨酸 gǔ ān suān
GABA γ-氨基丁酸 γ- ān jī dīng suān
endorphins 内啡肽 nèi fēi tài
substance P P物质 P wù zhì
acetylcholine 乙酰胆碱 yǐ xiān dǎn jiǎn
Hormones 激素 jī sù
adrenaline 肾上腺素 shèn shàng xiàn sù
leptin 瘦素 shòu sù
ghrelin 胃饥饿素 wèi jī è sù
melatonin 褪黑素 tuì hēi sù
oxytocin 催产素 cuī chǎn sù
Psychoactive drugs 精神药物 jīng shén yào wù
agonist 激动剂 jī dòng jì
antagonist 拮抗剂 jié kàng jì
reuptake inhibitor 再摄取抑制剂 zài shè qǔ yì zhì jì
stimulants 兴奋剂 xīng fèn jì
depressants 抑制剂 yì zhì jì
hallucinogens 致幻剂 zhì huàn jì
opioids 阿片类药物 ā piàn lèi yào wù
tolerance 耐受性 nài shòu xìng
addiction 成瘾 chéng yǐn
withdrawal 戒断反应 jiè duàn fǎn yìng
1.4

The Brain
Syllabus
Learning ObjectiveEssential Knowledge

1.4.A
Explain how the structures and functions of the brain apply to behavior and mental processes.

  • 1.4.A.1 The brain stem (including the medulla) generally controls basic functioning such as breathing and heart rate.
  • 1.4.A.2 The reticular activating system and the brain’s reward center generally control alertness, some voluntary movement, eye movement, and some types of learning, cognition, and emotion.
  • 1.4.A.3 The cerebellum generally controls coordination of muscle movement, balance, and some forms of procedural learning.
  • 1.4.A.4 The cerebral cortex is divided into two hemispheres and includes the limbic system (thalamus, hypothalamus, pituitary gland, hippocampus, amygdala), corpus callosum, and the lobes of the cortex.
    • 1.4.A.4.i The occipital lobes generally control visual information processing and are located in the rear of the brain.
    • 1.4.A.4.ii The temporal lobes generally control auditory and linguistic processing and are located on the sides of the brain.
    • 1.4.A.4.iii The parietal lobes generally control association areas, which process and organize information, and the somatosensory cortex, which processes touch sensitivity. These lobes are located near the back crown of the brain.
    • 1.4.A.4.iv The frontal lobes, located just behind the forehead, generally control linguistic processing, higher-order thinking, and executive functioning, especially in the prefrontal cortex. The motor cortex is located at the rear of the frontal lobes and controls most types of skeletal movement.
  • 1.4.A.5 Split brain research, achieved by severing the corpus callosum (often a treatment for severe epilepsy), reveals that the right and left hemispheres of the brain may specialize in different activities and functions.
    • 1.4.A.5.i Areas of the brain that affect language are typically located in the left hemisphere and include Broca’s area (responsible for speech production) and Wernicke’s area (responsible for speech comprehension). Damage to these parts of the brain can lead to aphasia.
    • 1.4.A.5.ii Researchers test for cortex specialization with split-brain patients by showing information in each visual field, taking advantage of the brain’s contralateral hemispheric organization.
  • 1.4.A.6 Brain plasticity is the ability of the brain to rewire itself or modify or create new connections throughout development and generally allows for the function of a damaged part of the brain to be assumed by a different part of the brain.
  • 1.4.A.7 Research on the brain is done using scans (including EEG and fMRI), case studies, and surgical procedures (such as lesioning) to promote understanding of how the different structures of the brain work and how the brain functions together as a whole.

Source: College Board AP Course and Exam Description

The brain is studied from the bottom up, because the lower structures handle the most basic jobs.

  • The brain stem 脑干, including the medulla 延髓, controls breathing and heart rate.
  • The reticular activating system 网状激活系统 controls alertness and arousal.
  • The cerebellum 小脑 controls coordination, balance, and some procedural learning 程序性学习.
  • The limbic system 边缘系统 sits inside the cerebral cortex and includes the thalamus 丘脑 (a relay station for the senses), the hypothalamus 下丘脑 (hunger, thirst, temperature), the pituitary gland 脑垂体, the hippocampus 海马体 (forming new memories), and the amygdala 杏仁核 (fear and emotion).

The cerebral cortex 大脑皮层 is divided into two hemispheres 半球 and four lobes: the occipital lobes 枕叶 process vision at the rear; the temporal lobes 颞叶 process hearing and language at the sides; the parietal lobes 顶叶 hold the somatosensory cortex 体感皮层 for touch; and the frontal lobes 额叶 handle higher-order thinking and executive function 执行功能.

Language sits mainly in the left hemisphere: Broca's area 布罗卡区 for speech production and Wernicke's area 韦尼克区 for comprehension.

Split-brain research 裂脑研究, done on patients whose corpus callosum 胼胝体 was cut to treat severe epilepsy, shows the two hemispheres can work independently. Researchers present information to one visual field 视野 at a time, because each field is processed by the opposite hemisphere.

Brain plasticity 大脑可塑性 is the brain's ability to rewire itself and form new connections, which supports recovery after damage. Research methods include EEG 脑电图 and fMRI 功能性磁共振成像 scans, case studies, and lesioning 损毁法.

Vocabulary Train
English Chinese Pinyin
brain stem 脑干 nǎo gàn
medulla 延髓 yán suǐ
reticular activating system 网状激活系统 wǎng zhuàng jī huó xì tǒng
cerebellum 小脑 xiǎo nǎo
procedural learning 程序性学习 chéng xù xìng xué xí
limbic system 边缘系统 biān yuán xì tǒng
thalamus 丘脑 qiū nǎo
hypothalamus 下丘脑 xià qiū nǎo
pituitary gland 脑垂体 nǎo chuí tǐ
hippocampus 海马体 hǎi mǎ tǐ
amygdala 杏仁核 xìng rén hé
cerebral cortex 大脑皮层 dà nǎo pí céng
hemispheres 半球 bàn qiú
occipital lobes 枕叶 zhěn yè
temporal lobes 颞叶 niè yè
parietal lobes 顶叶 dǐng yè
somatosensory cortex 体感皮层 tǐ gǎn pí céng
frontal lobes 额叶 é yè
executive function 执行功能 zhí xíng gōng néng
Broca's area 布罗卡区 bù luó kǎ qū
Wernicke's area 韦尼克区 wéi ní kè qū
Split-brain research 裂脑研究 liè nǎo yán jiū
corpus callosum 胼胝体 pián zhī tǐ
visual field 视野 shì yě
Brain plasticity 大脑可塑性 dà nǎo kě sù xìng
EEG 脑电图 nǎo diàn tú
fMRI 功能性磁共振成像 gōng néng xìng cí gòng zhèn chéng xiàng
lesioning 损毁法 sǔn huǐ fǎ
1.5

Consciousness and Sleep
Syllabus
Learning ObjectiveEssential Knowledge

1.5.A
Explain how the sleep/wake cycle affects behavior and mental processes throughout the day and night.

  • 1.5.A.1 Consciousness has varying levels of awareness of thoughts, feelings, behavior, and events in individuals’ internal and external worlds. Sleep and wakefulness are two types of consciousness.
  • 1.5.A.2 The sleep/wake cycle is a circadian rhythm, which in humans is about a 24-hour cycle. Jet lag and shift work are disruptions of the circadian rhythm.
  • 1.5.A.3 The stages of sleep are identified by their specific EEG patterns.
    • 1.5.A.3 .i NREM sleep occurs in Stages 1 through 3 and decreases in duration throughout the cycle. Hypnagogic sensations occur as one enters Initial Stage 1 sleep.
    • 1.5.A.3 .ii REM sleep is considered paradoxical because it produces waves similar to wakefulness, but the body is at its most relaxed. Dreaming typically occurs in REM sleep. The frequency of REM sleep typically increases as the cycle progresses. When deprived of REM sleep, REM rebound can occur.
  • 1.5.A.4 Theories regarding the structure and function of dreams include activation-synthesis and consolidation theory.
    • Exclusion Statement: The psychoanalytic theory of dreams is outside of the scope of the AP Psychology Exam.
  • 1.5.A.5 Memory consolidation and restoration are current theories about why sleep occurs. These theories suggest that sleep is useful for organizing and consolidating memories or restoring depleted resources used throughout a given day.
  • 1.5.A.6 Many disorders interrupt healthy sleep, and their effects on waking behavior and health vary. Sleep disruptions can affect physical and cognitive performance during wakefulness. Treating sleep disorders and following regular schedules for sleeping can improve waking performance and overall well-being. Disorders commonly studied in introductory psychology include insomnia, narcolepsy, REM sleep behavior disorder, sleep apnea, and somnambulism.
    • Exclusion Statement: The AP Psychology Exam will only address the listed disorders in EK 1.5.A.6.

Source: College Board AP Course and Exam Description

Consciousness 意识 is awareness of internal and external events, and it varies in level.

The sleep/wake cycle is a circadian rhythm 昼夜节律 of about 24 hours. Jet lag 时差反应 and shift work disrupt it.

Sleep stages are identified by EEG patterns. NREM sleep 非快速眼动睡眠 covers stages 1 to 3; hypnagogic sensations 入睡幻觉 occur as you fall asleep. REM sleep 快速眼动睡眠 is called paradoxical sleep 异相睡眠 because the brain looks awake while the body is most relaxed, and most dreaming happens here.

Two examinable theories explain dreams: activation-synthesis theory 激活-综合理论 (the brain interprets random activity) and consolidation theory 巩固理论 (dreams reflect memory processing). Sleep itself is explained by memory consolidation 记忆巩固 and restoration 恢复 theories.

Note: the psychoanalytic theory of dreams is outside the exam's scope.

Sleep disorders disrupt waking behavior and health: insomnia 失眠, narcolepsy 发作性睡病, sleep apnea 睡眠呼吸暂停, somnambulism 梦游 (sleepwalking), and REM sleep behavior disorder 快速眼动睡眠行为障碍.

Vocabulary Train
English Chinese Pinyin
Consciousness 意识 yì shí
circadian rhythm 昼夜节律 zhòu yè jié lǜ
Jet lag 时差反应 shí chà fǎn yìng
NREM sleep 非快速眼动睡眠 fēi kuài sù yǎn dòng shuì mián
hypnagogic sensations 入睡幻觉 rù shuì huàn jué
REM sleep 快速眼动睡眠 kuài sù yǎn dòng shuì mián
paradoxical sleep 异相睡眠 yì xiāng shuì mián
activation-synthesis theory 激活-综合理论 jī huó - zōng hé lǐ lùn
consolidation theory 巩固理论 gǒng gù lǐ lùn
memory consolidation 记忆巩固 jì yì gǒng gù
restoration 恢复 huī fù
insomnia 失眠 shī mián
narcolepsy 发作性睡病 fā zuò xìng shuì bìng
sleep apnea 睡眠呼吸暂停 shuì mián hū xī zàn tíng
somnambulism 梦游 mèng yóu
REM sleep behavior disorder 快速眼动睡眠行为障碍 kuài sù yǎn dòng shuì mián xíng wéi zhàng ài
1.6

Sensation
Syllabus
Learning ObjectiveEssential Knowledge

1.6.A
Explain how the process of sensation is related to behavior and mental processes.

  • 1.6.A.1 Sensation is the process of detecting information from the environment that meets a certain threshold and transducing stimuli into neurochemical messages for processing (perception) in the brain. The absolute threshold occurs when a stimulus can be detected at least 50% of the time.
  • 1.6.A.2 Detection of change in stimuli or diminished sensitivity to stimuli can be explained by the just-noticeable difference and sensory adaptation. Weber’s law describes the degree to which stimuli need to be different for the difference to be detected.
  • 1.6.A.3 The sensory systems constantly work together in a process called sensory interaction. Synesthesia is an experience of sensation in which one system of sensation is experienced through another.

1.6.B
Explain how the structures and functions of the visual sensory system relate to behavior and mental processes.

  • 1.6.B.1 The retina is the photosensitive surface at the back of the eye. Cells in the retina capture visual information that is transduced to the brain for processing. Evidence of incomplete images captured by the retina is demonstrated by the presence of the blind spot, where the visual nerve exits the eye. The brain fills in the gaps in the incomplete retinal images to perceive a relatively complete picture of the world.
  • 1.6.B.2 Visual stimuli are focused onto the retina by the lens via a process called accommodation. When this process is altered, nearsightedness or farsightedness can result.
  • 1.6.B.3 Cells that lie in the periphery of the eye and detect shapes and movement, but not color, are called rods. These cells are mainly activated in low-light environments. These cells play a role in light and dark adaptation.
  • 1.6.B.4 Color vision is explained by both the trichromatic theory and the opponent-process theory.
    • 1.6.B.4.i Photoreceptor cells located in the fovea of the eye that process color and detail are called cones. Researchers have identified blue (detecting short wavelengths), green (detecting medium wavelengths) and red (detecting long wavelengths) cones in the retina.
    • 1.6.B.4.ii Afterimages result when certain ganglion cells in the retina are activated while others are not. The ganglion cells involved in this opponent process are red/green, blue/ yellow/ and black/white.
    • 1.6.B.4.iii Color vision deficiency involves damage or irregularities to one or more cones or ganglion cells (red/green, blue/ yellow). Color vision deficiency includes dichromatism or monochromatism.
  • 1.6.B.5 Damage to parts of the brain responsible for vision (mainly the occipital lobes) can result in disorders such as prosopagnosia (face blindness) and blindsight.

1.6.C
Explain how the structures and functions of the auditory sensory system relate to behavior and mental processes.

  • 1.6.C.1 Sound occurs through the movement of air molecules at different wavelengths (called pitch) and amplitudes (called loudness).
  • 1.6.C.2 Theories that help explain pitch perception include place theory, volley theory, and frequency theory.
  • 1.6.C.3 Sound localization describes how we identify where sounds in our environment are coming from.
  • 1.6.C.4 Hearing difficulties can result from aging and various kinds of damage to auditory structures. Types of hearing loss include conduction deafness and sensorineural deafness.

1.6.D
Explain how the structures and functions of the chemical sensory systems relate to behavior and mental processes.

  • 1.6.D.1 Structures in the nose and brain process and/ or transduce olfactory stimuli. Smell is the only sense not processed first in the thalamus of the brain. Pheromones produce chemical messages for the olfactory system.
  • 1.6.D.2 Gustation is the sense of taste, and types of tastes include sweet, sour, salty, bitter, umami, and oleogustus.
  • 1.6.D.3 Structures in the tongue, mouth, and brain process and/or transduce basic tastes. The number of taste receptors on the tongue is related to how sensitive people are to tastes, classifying them as supertasters, medium tasters, or nontasters.
  • 1.6.D.4 The chemical senses interact to create the sensation of taste. Without the sense of smell, taste sensations are either muted or not experienced.

1.6.E
Explain how the structures and functions of the touch sensory system relate to behavior and mental processes.

  • 1.6.E.1 Structures within the skin and brain process and/or transduce touch stimuli. The sensation of “hot” is produced by the activation of warm and cold receptors in the skin.

1.6.F
Explain how the structures and functions of the pain sensory system relate to behavior and mental processes.

  • 1.6.F.1 Pain is processed both in the body and in the brain. Gate control theory is one attempt to describe the complexities of pain. Phantom limb sensation occurs when people who have lost limbs report sensation or pain where the limb used to be.

1.6.G
Explain how the structures and functions that maintain balance (vestibular) and body movement (kinesthetic) relate to behavior and mental processes.

  • 1.6.G.1 The vestibular sense controls balance and is primarily detected by the semicircular canals and structures in the brain.
  • 1.6.G.2 Kinesthesis the sense of one’s body movement. Kinesthesis allows the body to move in coordinated ways without having to look at the various parts of the body as it moves.

Source: College Board AP Course and Exam Description

Sensation 感觉 is detecting information from the environment and transducing 转导 it into neural signals the brain can use. Detection needs a certain absolute threshold 绝对阈限.

  • The just-noticeable difference 最小可觉差 is the smallest change a person can detect.
  • Sensory adaptation 感觉适应 is reduced sensitivity to an unchanging stimulus - you stop noticing a smell.
  • Sensory interaction 感觉相互作用 means the senses work together. Synesthesia 联觉 is when one sense triggers another.

Vision. Light is focused onto the retina 视网膜 by the lens 晶状体 changing shape, a process called visual accommodation 视觉调节; when this fails the result is nearsightedness 近视 or farsightedness 远视. Rods 视杆细胞 lie in the periphery and detect shape and movement in low light. Cones 视锥细胞 sit in the fovea 中央凹 and detect colour and detail. Colour vision needs two theories: trichromatic theory 三色理论 (blue, green and red cones) and opponent-process theory 对立过程理论, which explains afterimages 后像. Damage to the occipital lobes can cause prosopagnosia 面孔失认症, or face blindness.

Hearing. Sound is air movement; wavelength gives pitch 音高 and amplitude gives loudness 响度. Pitch perception is explained by place theory 位置理论, volley theory 齐射理论, and frequency theory 频率理论. Sound localization 声源定位 tells us where a sound comes from. Hearing loss may be conduction deafness 传导性耳聋 or sensorineural deafness 感音神经性耳聋.

The chemical senses. Olfaction 嗅觉 is the only sense not relayed first through the thalamus. Gustation 味觉 covers sweet, sour, salty, bitter, umami 鲜味, and oleogustus 脂味. The two interact: without smell, taste is muted.

Touch, pain, and body position. Skin receptors transduce touch; "hot" comes from warm and cold receptors firing together. Pain is processed in body and brain, and gate control theory 闸门控制理论 explains why attention changes how much it hurts; phantom limb 幻肢 sensations show the brain's role. The vestibular sense 前庭觉 controls balance through the semicircular canals 半规管, and kinesthesis 动觉 is the sense of body movement.

Worked example (a real AP exam question). The 2025 Article Analysis Question asked students to "Identify the research method used in the study" and then to "Explain the extent to which the research findings may or may not be generalizable using specific and relevant evidence from the study." A full-mark answer to the second part names the limitation and ties it to evidence: "The findings may not generalize widely because participants were undergraduate students at one university, so the sample was not representative of the general population." Notice the shape: Explain needs a claim plus the evidence behind it. Naming the method alone answers part A, not part E.

Vocabulary Train
English Chinese Pinyin
Sensation 感觉 gǎn jué
transducing 转导 zhuǎn dǎo
absolute threshold 绝对阈限 jué duì yù xiàn
just-noticeable difference 最小可觉差 zuì xiǎo kě jué chà
Sensory adaptation 感觉适应 gǎn jué shì yìng
Sensory interaction 感觉相互作用 gǎn jué xiāng hù zuò yòng
Synesthesia 联觉 lián jué
retina 视网膜 shì wǎng mó
lens 晶状体 jīng zhuàng tǐ
visual accommodation 视觉调节 shì jué tiáo jié
nearsightedness 近视 jìn shì
farsightedness 远视 yuǎn shì
Rods 视杆细胞 shì gān xì bāo
Cones 视锥细胞 shì zhuī xì bāo
fovea 中央凹 zhōng yāng āo
trichromatic theory 三色理论 sān sè lǐ lùn
opponent-process theory 对立过程理论 duì lì guò chéng lǐ lùn
afterimages 后像 hòu xiàng
prosopagnosia 面孔失认症 miàn kǒng shī rèn zhèng
pitch 音高 yīn gāo
loudness 响度 xiǎng dù
place theory 位置理论 wèi zhì lǐ lùn
volley theory 齐射理论 qí shè lǐ lùn
frequency theory 频率理论 pín lǜ lǐ lùn
Sound localization 声源定位 shēng yuán dìng wèi
conduction deafness 传导性耳聋 chuán dǎo xìng ěr lóng
sensorineural deafness 感音神经性耳聋 gǎn yīn shén jīng xìng ěr lóng
Olfaction 嗅觉 xiù jué
Gustation 味觉 wèi jué
umami 鲜味 xiān wèi
oleogustus 脂味 zhī wèi
gate control theory 闸门控制理论 zhá mén kòng zhì lǐ lùn
phantom limb 幻肢 huàn zhī
vestibular sense 前庭觉 qián tíng jué
semicircular canals 半规管 bàn guī guǎn
kinesthesis 动觉 dòng jué
1.6

Exam tips
  • Learn only the listed neurotransmitters and hormones; the exam will not ask about others, and the endocrine glands are out of scope apart from the pituitary.
  • Keep sensation separate from perception: sensation is detecting and transducing, perception is interpreting (Unit 2).
  • The all-or-none principle means intensity is coded by how often a neuron fires, never by how strongly.
  • Match structure to job before you write: hippocampus forms memories, amygdala handles fear, cerebellum coordinates movement.
  • Sympathetic arouses, parasympathetic calms. If a question describes a racing heart, name the sympathetic branch.
  • Say what a scan can and cannot show. fMRI shows activity over time; EEG shows electrical patterns and identifies sleep stages.

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