📚 Cambridge IGCSE Psychology: Formula & Theorem Quick Reference Handbook | 剑桥 IGCSE 心理学公式定理速查手册
This handbook distils the essential laws, models, and principles of Cambridge IGCSE Psychology into a 'formula-style' reference sheet. Each entry presents a core finding in a memorable, diagram-friendly format that mirrors the kind of statement you might use to structure a 6-mark or 9-mark answer. Use it to link theory names, key equations, and classic experiments as you revise.
本手册将剑桥 IGCSE 心理学考试中必知的核心定律、模型和原理凝练成“公式式”速查表，每一条都按照可以直接用于中等或长篇答题的格式编排。复习时，你可以快速对照理论名称、关键方程和经典实验，把抽象概念转化为结构化得分点。
1. Multi-Store Model of Memory (Atkinson & Shiffrin) | 多储存记忆模型
The Atkinson-Shiffrin model (1968) describes memory as a linear flow through three distinct stores. Information passes from sensory memory into short-term memory (STM) via attention, and then into long-term memory (LTM) through maintenance rehearsal. Without rehearsal, decay or displacement occurs.
阿特金森—谢夫林模型（1968）将记忆描述为三个独立储存库的线性传递：信息通过注意从感觉记忆进入短时记忆，再通过维持性复述进入长时记忆；缺少复述则发生衰退或被新的信息挤掉。
| Store | Capacity | Duration |
| Sensory memory | Very large | < 0.5 s (iconic) / 2-3 s (echoic) |
| Short-term memory (STM) | 7 ± 2 chunks | 18-30 s (without rehearsal) |
| Long-term memory (LTM) | Unlimited | Potentially a lifetime |
Evidence for separate STM and LTM includes the case of HM (Milner, 1966) and the serial position effect. The model remains a foundation, although later working memory models view STM as an active processor rather than a simple store.
支持独立短时与长时储存的证据包括 HM 案例（Milner, 1966）和顺序位置效应。尽管后来的工作记忆模型将短时记忆视为主动加工系统，这一模型仍是理解记忆结构的基石。
2. Miller's Law (The Magic Number 7 ± 2) | 米勒定律（神奇数字 7 ± 2）
Miller (1956) proposed that the capacity of short-term memory is limited to about seven meaningful items, plus or minus two. A 'chunk' is a grouping of information that carries meaning, such as a word or a familiar date. This explains why chunking information (e.g., grouping digits into a phone number) improves recall.
米勒（1956）提出，短时记忆的容量大约为七个有意义的项目，上下浮动两个。一个“组块”是指对个人有意义的信息群组，比如一个词语或一个熟悉的日期。这就是为什么把信息组块化（如将数字分组为电话号码）能提高回忆成绩。
STM Capacity ≈ 7 ± 2 chunks
In digit span tests, most adults repeat between five and nine digits. Jacobs (1887) provided early evidence, and the principle remains central to understanding the bottleneck of information processing before rehearsal or encoding into LTM.
在数字广度测试中，大多数成年人能复述 5 到 9 个数字。Jacobs（1887）提供了早期证据，这一原理至今仍是理解信息在复述或编码进入长时记忆前瓶颈的核心。
3. Serial Position Effect | 顺序位置效应
When participants attempt to recall a list of items, recall accuracy is highest for the first few items (primacy effect) and the last few items (recency effect), while items in the middle are recalled least well. This pattern supports the distinction between LTM (primacy, due to rehearsal) and STM (recency, due to still being in phonological loop).
当参与者试图回忆一系列项目时，最先呈现的少数项目（首因效应）和最后呈现的少数项目（近因效应）回忆正确率最高，中间项目回忆最差。这一模式支持长时记忆（首因，因复述进入）和短时记忆（近因，仍在语音回路中）的分离。
Recall probability = f(Position), with maximum at beginning and end
Murdock (1962) demonstrated the U-shaped curve. Introducing a distractor task before recall eliminates the recency effect but leaves the primacy effect intact, confirming that recency relies on a short-term store.
Murdock（1962）证实了这条 U 型曲线。在回忆前引入分心任务会消除近因效应，但首因效应保留，这就证明近因依赖短期存储。
4. Ebbinghaus Forgetting Curve | 艾宾浩斯遗忘曲线
Hermann Ebbinghaus (1885) measured how quickly newly learned nonsense syllables are forgotten over time. The curve shows a rapid drop in retention within the first hour, followed by a more gradual decline. The shape can be approximated by an exponential decay function.
赫尔曼·艾宾浩斯（1885）测量了刚学会的无意义音节随时间的遗忘速率。曲线显示在学习后第一个小时内记忆保持量急速下降，随后衰减趋缓。其形状可用指数衰减函数近似描述。
Retention ∝ e-t / τ (rapid initial decay, then plateau)
Ebbinghaus also identified that distributed practice leads to better long-term retention than massed practice, a principle captured by the 'spacing effect'. The curve underscores why revision must be spaced across weeks rather than crammed.
艾宾浩斯还发现分散练习比集中练习更能促进长期记忆保持，这一原则被称为“间隔效应”。曲线揭示了为何复习必须分散在数周进行，而非临时抱佛脚。
5. Interference Theory of Forgetting | 遗忘的干扰理论
Interference theory states that forgetting in LTM occurs because similar memories compete and disrupt retrieval. Two types of interference are identified: proactive interference (old learning blocks new) and retroactive interference (new learning blocks old).
干扰理论指出，长时记忆中遗忘的发生是因为相似记忆相互竞争、干扰提取。主要分为两类干扰：前摄干扰（旧知识阻碍新知识）和倒摄干扰（新知识阻碍旧知识）。
Proactive: Old → blocks New ; Retroactive: New → blocks Old
Underwood (1957) found that participants recalled fewer nonsense syllables the more previous lists they had learned, illustrating proactive interference. McGeoch and McDonald (1931) provided evidence for retroactive interference, showing that similarity amplifies confusion.
Underwood（1957）发现参与者先前学习的无意义音节清单越多，回忆数量越少，表明前摄干扰。McGeoch 和 McDonald（1931）通过实验为倒摄干扰提供了证据，证明相似性会增强混淆。
6. Bartlett's Reconstructive Memory | 巴特利特的重构记忆理论
Bartlett (1932) argued that memory is not a passive retrieval of stored records but an active reconstruction shaped by schemas—mental frameworks of past experiences and cultural expectations. Recall tends to be distorted towards what is familiar and meaningful.
巴特利特（1932）主张，记忆并非对储存记录的被动提取，而是一个由图式（过去经验与文化期待的 mental framework）引导的主动重构过程。回忆往往会向熟悉、有意义的方向扭曲。
Memory = f(Original event, Schema, Current context)
In his 'War of the Ghosts' study, British participants repeatedly shortened, rationalised, and altered unfamiliar elements of a Native American story to fit their own schema. This illustrates omissions, transformations, and confabulations—key distortions in reconstructive memory.
在“幽灵之战”研究中，英国参与者反复缩短、合理化并修改不熟悉的北美原住民故事，以符合自己的图式，这体现了遗漏、转换和虚构等重构记忆中的典型扭曲形式。
7. Weber's Law | 韦伯定律
Weber's Law states that the just noticeable difference (JND) between two stimuli is proportional to the magnitude of the original stimulus. The Weber fraction is constant within a given sense modality (e.g., weight, light, sound) but differs between modalities.
韦伯定律指出，两个刺激之间刚刚可察觉的差异（JND）与原始刺激的强度成正比。韦伯分数在同一感觉通道内（如重量、光线、声音）是常数，但在不同通道间不同。
ΔI / I = k (constant Weber fraction)
For lifted weights, k ≈ 0.02–0.03; for brightness of lights, k ≈ 0.01– helps explain why we notice adding a 1-g weight to a 20-g object but not to a 200-g object—a principle relevant to sensory thresholds and perceptual sensitivity.
在提举重量实验中，k ≈ 0.02–0.03；在光线亮度辨别中，k ≈ 0.01–0.02。这一定律解释了为什么我们在 20 克物体上增加 1 克能察觉，而在 200 克物体上增加 1 克却难以分辨——这对感觉阈限和知觉敏感度很有意义。
8. Size Constancy and Depth Cues | 大小恒常性与深度线索
Size constancy is the ability to perceive an object as having a constant size despite changes in the size of its retinal image. This is achieved by the visual system combining retinal size with depth cues. The formula-like relationship is known as the size-distance invariance hypothesis.
大小恒常性是指尽管物体在视网膜上成像的大小变化，知觉到的物体大小仍保持恒定的能力。视觉系统通过将视网膜大小与深度线索结合来实现这一点，其关系可用尺寸—距离不变假设表达为公式形式。
Perceived size ∝ Retinal size × Perceived distance
Pictorial depth cues (linear perspective, texture gradient, relative height, superimposition) and physiological cues (convergence, retinal disparity) contribute to distance perception. Ames room illusions exploit manipulated depth cues to break size constancy.
图画深度线索（线条透视、纹理梯度、相对高度、遮挡）和生理线索（辐辏、视网膜像差）共同参与距离知觉。艾姆斯房间错觉正是通过操控深度线索来破坏大小恒常性。
9. Asch's Conformity Paradigm | 阿希从众范式
Solomon Asch (1951) demonstrated that a unanimous majority can exert powerful influence over an individual's perceptual judgements, even when the correct answer is obvious. The conformity rate can be expressed as the proportion of critical trials on which participants agreed with the clearly wrong majority.
所罗门·阿希（1951）证明，即使正确答案一目了然，一致的大多数也能极大地影响个体的知觉判断。从众率可表示为参与者在关键试次中同意明显错误的大多数的比例。
Conformity rate ≈ 37 % (Asch, 1956, averaged across critical trials)
Key variables affecting conformity are group size (conformity peaks at 3–5 confederates), unanimity (a single dissenter drastically reduces conformity), and task difficulty. Asch's work remains a classic illustration of normative social influence.
影响从众的关键变量包括群体规模（从众在 3–5 名同谋者时达到峰值）、一致性（只要有一名异议者就能大幅降低从众）和任务难度。阿希的研究仍然是规范性社会影响的经典说明。
10. Milgram's Obedience Experiment | 米尔格拉姆服从实验
Stanley Milgram (1963) found that 65 % of participants were willing to administer what they believed to be a lethal 450-volt shock to another person when instructed by an authority figure. The obedience rate is the proportion of participants who reached the maximum voltage level.
斯坦利·米尔格拉姆（1963）发现，在权威人物的指导下，65% 的参与者愿意向另一人施加他们认为致命的 450 伏电击。服从率是指达到最高电压水平的参与者比例。
Obedience = Number going to 450 V / Total participants ≈ 0.65
Situational factors such as proximity of the victim, proximity of the authority, and the presence of disobedient peers dramatically alter obedience rates. The agency theory (Milgram, 1974) proposes that individuals shift from an autonomous to an agentic state when following authority.
情境因素（受害者接近度、权威接近度、是否存在不服从的同伴）会显著改变服从率。代理状态理论（Milgram, 1974）提出，个体在服从权威时会从自主状态转换到代理状态。
11. Zimbardo's Deindividuation (Stanford Prison Experiment) | 津巴多去个性化（斯坦福监狱实验）
Zimbardo's (1973) Stanford Prison Experiment illustrated how social roles, anonymity, and power differentials can trigger deindividuation—a state of reduced self-awareness and weakened personal restraint. Deindividuation leads to behaviour that is less regulated by personal norms.
津巴多（1973）的斯坦福监狱实验展示了社会角色、匿名性和权力差异如何引致去个性化——一种自我意识减弱、个人约束降低的状态。去个性化会导致行为较少受个人规范约束。
Deindividuation ∝ (Anonymity × Diffusion of responsibility) – Self-awareness
Guards' escalating cruelty and prisoners' submissive breakdowns highlighted the power of the situation over disposition. The study is a powerful demonstration of how ordinary people can engage in extreme behaviours when embedded in deindividuating environments.
看守逐渐升级的残酷行为和囚犯的顺从崩溃，凸显了情境对性格的强大作用。该研究有力地表明，普通人在去个性化的环境嵌入中可能做出极端行为。
12. Bystander Effect (Latane & Darley) | 旁观者效应（拉塔内与达利）
The bystander effect refers to the finding that individuals are less likely to offer help in an emergency when other people are present. The probability of intervention decreases as the number of bystanders increases. This is explained by diffusion of responsibility and pluralistic ignorance.
旁观者效应是指，在紧急情况下，旁观者在有其他人在场时提供帮助的倾向更低，且干预概率随旁人数增多而下降。这一点可以由责任分散和多数无知来解释。
P(helping) ∝ 1 / (Number of bystanders)
Latane and Darley (1968) proposed a five-step decision model: notice the event, interpret it as an emergency, assume personal responsibility, know how to help, and implement the decision. The presence of others can block the third step.
拉塔内和达利（1968）提出五步决策模型：注意事件、解释为紧急情况、承担个人责任、知晓如何帮助、执行帮助。他人的在场可能阻断第三步——承担责任。
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