D2.Psy.8.9-12: The Complexity of Thought and the Factors Behind Individual Differences

Overview

Lesson Procedure

60-70 minutes of class time across 5 phases.

1. Warm-Up5-10 minutes
2. Direct Instruction20 minutes
3. Guided Practice15 minutes
4. Independent Practice15 minutes
5. Closure5-10 minutes

1. Warm-Up5-10 minutes

   Warm-Up Prompt

   "Close your eyes and picture the front door of your home. How clear is the picture: like a photograph, like a faint sketch, or no picture at all, just knowing what it looks like? Write one sentence, then guess how a classmate would answer."

   Take a quick, anonymous show of fingers from 1 (no picture) to 5 (photograph). Classes usually spread across the whole scale, and some students are surprised that others experience something very different. Ask: if people differ this much on something so ordinary, what does that say about studying thought? Keep the question open for Source 1.

2. Direct Instruction20 minutes

   Psychology explains both what people share and how they differ. Thought is complex: it cannot be watched directly, it changes from moment to moment, and it depends on what each person attends to. Differences between people are complex too, because they come from many factors that act together. The vocabulary below organizes the lesson.

   Complexity and individual differences: the working vocabulary (examples written for this page)

   Term	What it means	Example
   Individual differences	Relatively lasting ways in which people differ in thought, feeling and behavior	Some people picture scenes vividly; others think mostly in words
   Trait and state	A trait is a lasting tendency; a state is a temporary condition	Being generally outgoing (trait) versus feeling tired today (state)
   Selective attention	Noticing some parts of a situation and ignoring others	Hearing your own name across a noisy cafeteria
   Self-report	A person's own account of their experience, the only direct window on private thought	Rating how clear a mental picture is
   Genetic factors	Differences in inherited DNA that influence development	Gene variants inherited from each parent
   Environmental factors	Influences from outside the person's genes	Home, schooling, learning resources, healthcare, nutrition, culture
   Gene-environment interplay	Genes and environment influence each other, so their effects are hard to separate	A child who enjoys reading seeks out books, which builds reading skill further
   Heritability	The share of the variation in a trait, within a particular group and setting, that is linked to genetic differences	A statement about a group's spread of scores, not about how much of one person's trait comes from genes
   Multiple causation	A behavior has several causes that combine; no single factor decides it	A test score depends on knowledge, sleep, interest, practice and the test itself

   Difference, not deficit. Some people report no visual imagery at all. In a 2015 report in Cortex, "Lives without imagery: Congenital aphantasia," Adam Zeman of the University of Exeter Medical School and colleagues used the name "aphantasia" for this. It is described as a variation in experience, and, as Source 3 shows, people often do not realize that others experience imagery differently. The point for this lesson: a difference in how people think is not automatically a weakness.

   The sources. Sources 1 and 2 come from William James's The Principles of Psychology (1890), chapter IX, "The Stream of Thought." Read them with the class.

   1The first fact for us, then, as psychologists, is that thinking of some sort goes on. I use the word thinking, in accordance with what was said on p. 186, for every form of consciousness indiscriminately. If we could say in English 'it thinks,' as we say 'it rains' or 'it blows,' we should be stating the fact most simply and with the minimum of assumption. As we cannot, we must simply say that thought goes on.

   [...]

   2How does it go on? We notice immediately five important characters in the process, of which it shall be the duty of the present chapter to treat in a general way:

   31) Every thought tends to be part of a personal consciousness.

   42) Within each personal consciousness thought is always changing.

   53) Within each personal consciousness thought is sensibly continuous.

   64) It always appears to deal with objects independent of itself.

   75) It is interested in some parts of these objects to the exclusion of others, and welcomes or rejects - chooses from among them, in a word - all the while.

   1That industry goes on to deal with the things thus given in perception. A man's empirical thought depends on the things he has experienced, but what these shall be is to a large extent determined by his habits of attention. A thing may be present to him a thousand times, but if he persistently fails to notice it, it cannot be said to enter into his experience. We are all seeing flies, moths, and beetles by the thousand, but to whom, save an entomologist, do they say anything distinct? On the other hand, a thing met only once in a lifetime may leave an indelible experience in the memory. Let four men make a tour in Europe. One will bring home only picturesque impressions - costumes and colors, parks and views and works of architecture, pictures and statues. To another all this will be non-existent; and distances and prices, populations and drainage-arrangements, door-and window-fastenings, and other useful statistics will take their place. A third will give a rich account of the theatres, restaurants, and public balls, and naught beside; whilst the fourth will perhaps have been so wrapped in his own subjective broodings as to tell little more than a few names of places through which he passed. Each has selected, out of the same mass of presented objects, those which suited his private interest and has made his experience thereby.

   2If, now, leaving the empirical combination of objects, we ask how the mind proceeds rationally to connect them, we find selection again to be omnipotent. In a future chapter we shall see that all Reasoning depends on the ability of the mind to break up the totality of the phenomenon reasoned about, into parts, and to pick out from among these the particular one which, in our given emergency, may lead to the proper conclusion. Another predicament will need another conclusion, and require another element to be picked out. The man of genius is he who will always stick in his bill at the right point, and bring it out with the right element - 'reason' if the emergency be theoretical, 'means' if it be practical - transfixed upon it. I here confine myself to this brief statement, but it may suffice to show that Reasoning is but another form of the selective activity of the mind.

   [...]

   3Ascending, still higher, we reach the plane of Ethics, where choice reigns notoriously supreme. An act has no ethical quality whatever unless it be chosen out of several all equally possible. [...]

   4Looking back, then, over this review, we see that the mind is at every stage a theatre of simultaneous possibilities.

   • Applying the five characters: Source 1

     You are reading in a noisy room and do not hear the conversation next to you until someone says your name. Which of James's five characters does this show?

     Result: The fifth: thought "is interested in some parts of these objects to the exclusion of others" and chooses among them. Attention selected one sound, your name, from many. The example also shows why thought is hard to study: the other sounds reached your ears but never entered your experience.

   • Knowledge shapes what we notice: Source 2, paragraph 1

     Why does James say that flies, moths and beetles say something distinct only to an entomologist?

     Result: An entomologist (an insect scientist) has the knowledge and the interest that make insects worth attending to, so the same sights carry information for that person and not for others. What a person has learned is one of the factors that make experience differ from person to person.

   • Heritability depends on the setting (invented example)

     Community X gives every child the same well-equipped school; Community Y has some excellent schools and some with few resources. In which community would differences in reading skill be more closely linked to genetic differences?

     Result: Community X. When environments are more alike, less of the variation between children can come from the environment, so a larger share is linked to genetic differences. Heritability is not a fixed property of a trait: it describes the sources of variation in a particular group and setting, and it changes when the setting changes.

   • One behavior, many causes (invented example)

     Two friends of similar ability take the same history quiz. One scores 18 of 20, the other 12. List four factors that could contribute to the 6-point difference.

     Result: Prior knowledge of the topic, hours of sleep the night before, interest in the subject, and test anxiety are four possibilities; practice with this quiz format is a fifth. Usually several combine. Explaining the difference means measuring more than one factor, not picking the most obvious one.

   • Self-report and its limits

     Everyone in a class says they "see" a picture of their front door. Does that mean they all experience the same thing?

     Result: Not necessarily. Private experience can only be reported in words, and people use the same words for different experiences; James notes that each thought belongs to "a personal consciousness." Careful questionnaires give a scale with described points, ask for examples, and check that answers stay consistent.

   Close the segment by asking students which factors from the vocabulary table could explain the warm-up spread in imagery.

3. Guided Practice15 minutes

   Read Source 5 together. It is an invented study with invented data and a very small sample, 12 adults; its numbers show how to reason about individual differences, not how common any kind of imagery really is.

   1Invented study summary, written for this page. A research team recruited 12 adult volunteers, coded A to L, to look at individual differences in mental imagery. Everyone gave written consent and could stop at any time, and no names were kept with the data.

   2Each volunteer did three things. First, they pictured their breakfast table from that morning and rated how clear the picture was, from 1 (no picture at all, I just know what was there) to 5 (as clear as really seeing it). Second, they studied a detailed drawing of a kitchen for 60 seconds and, 10 minutes later, wrote down every detail they remembered; a scorer who had not seen the imagery ratings counted correct details, out of 20. Third, they reported how many hours a week they usually spend drawing, painting or designing.

   3Imagery ratings, A to L: 5, 4, 1, 3, 5, 2, 4, 3, 1, 4, 3, 5. Details recalled, A to L: 16, 8, 13, 9, 14, 15, 16, 12, 14, 12, 11, 14. Hours a week of drawing, painting or designing, A to L: 3, 1, 4, 0, 2, 1, 6, 0, 2, 3, 1, 1.

   4The team's note: "Twelve volunteers are far too few to say how common each kind of imagery is, or to rule out other explanations. The data show how much people can differ on a task that looks simple."

   Imagery ratings in Source 5 (invented data): how many volunteers chose each rating

   Rating	1	2	3	4	5
   Number of volunteers	2	1	3	3	3

   1. Describe the ratings. The 12 ratings add to 40, so the mean is 40 / 12 ≈ 3.3. In order, the 6th and 7th ratings are 3 and 4, so the median is 3.5. Every point on the scale was used: individual differences in imagery are large even in a group of 12.
   2. Compare by imagery. Volunteers who rated 4 or 5 (A, B, E, G, J, L) recalled 16, 8, 14, 16, 12 and 14 details: 80 / 6 ≈ 13.3. Volunteers who rated 1 to 3 (C, D, F, H, I, K) recalled 13, 9, 15, 12, 14 and 11: 74 / 6 ≈ 12.3. The difference is about 1 detail.
   3. Look at Diagram 1. Ask: is there a clear upward pattern from rating 1 to rating 5? What other factor in paragraph 3 could be checked next? Pairs then compare the volunteers by hours of drawing, painting or designing; the result returns in the quiz.
4. Independent Practice15 minutes

   Students read Sources 3 and 4 on their own and use them, with Sources 1, 2 and 5, for the quiz and homework.

   Read Source 3 with care. Francis Galton's imagery questionnaire is a landmark in the study of individual differences, but two parts of his work are flagged here. First, Galton describes people without imagery as having "a mental deficiency." That framing is outdated: such differences are now studied as variation in experience. Second, Galton founded eugenics, the idea of "improving" humanity by controlling who has children; the preface to this edition of his book calls the book the starting point of that movement. Eugenics was used to justify forced sterilization laws in the United States, and in Buck v. Bell, 274 U.S. 200 (1927), the Supreme Court upheld one of them, a Virginia law. It is rejected today as unscientific and harmful. This lesson uses only Galton's questionnaire.

   Source 4 is a current explanation from the National Library of Medicine, a federal agency.

   1The first group of the rather long series of queries related to the illumination, definition, and colouring of the mental image, and were framed thus:--

   2"Before addressing yourself to any of the Questions on the opposite page, think of some definite object--suppose it is your breakfast-table as you sat down to it this morning--and consider carefully the picture that rises before your mind's eye."

   31. Illumination.--Is the image dim or fairly clear? Is its brightness comparable to that of the actual scene?

   42. Definition.--Are all the objects pretty well defined at the same time, or is the place of sharpest definition at any one moment more contracted than it is in a real scene?

   53. Colouring.--Are the colours of the china, of the toast, bread-crust, mustard, meat, parsley, or whatever may have been on the table, quite distinct and natural?

   6The earliest results of my inquiry amazed me. I had begun by questioning friends in the scientific world, as they were the most likely class of men to give accurate answers concerning this faculty of visualising, to which novelists and poets continually allude, which has left an abiding mark on the vocabularies of every language, and which supplies the material out of which dreams and the well-known hallucinations of sick people are built.

   7To my astonishment, I found that the great majority of the men of science to whom I first applied protested that mental imagery was unknown to them, and they looked on me as fanciful and fantastic in supposing that the words "mental imagery" really expressed what I believed everybody supposed them to mean. They had no more notion of its true nature than a colour-blind man, who has not discerned his defect, has of the nature of colour. They had a mental deficiency of which they were unaware, and naturally enough supposed that those who affirmed they possessed it, were romancing. [...]

   [...]

   8On the other hand, when I spoke to persons whom I met in general society, I found an entirely different disposition to prevail. Many men and a yet larger number of women, and many boys and girls, declared that they habitually saw mental imagery, and that it was perfectly distinct to them and full of colour. The more I pressed and cross-questioned them, professing myself to be incredulous, the more obvious was the truth of their first assertions. [...]

   1Like most aspects of human behavior and cognition, intelligence is a complex trait that is influenced by both genetic and environmental factors.

   2Intelligence is challenging to study, in part because it can be defined and measured in different ways. Most definitions of intelligence include the ability to learn from experiences and adapt to changing environments. Elements of intelligence include the ability to reason, plan, solve problems, think abstractly, and understand complex ideas. Many studies rely on a measure of intelligence called the intelligence quotient (IQ).

   3Researchers have conducted many studies to look for genes that influence intelligence. Since it is difficult to separate the genetic and environmental influences of a trait like intelligence, these studies can be complicated. Many of these studies have focused on similarities and differences in IQ within families, particularly looking at adopted children and twins. Other studies have examined variations across the entire genomes of many people (an approach called genome-wide association studies or GWAS) to determine whether any specific areas of the genome are associated with IQ. Studies have shown that intelligence has a genetic component, but they have not conclusively identified any single genes that have major roles in differences in intelligence. It is likely that intelligence involves many genes that each make only a small contribution to a person’s intelligence. Other areas that contribute to intelligence, such as memory and verbal ability, involve additional genetic factors. The genetic influences on intelligence is an ongoing area of research.

   4Intelligence is also strongly influenced by the environment. During a child's development, factors that contribute to intelligence include their home environment and parenting, education and availability of learning resources, and healthcare and nutrition. A person’s environment and genes influence each other, and it can be challenging to tease apart the effects of the environment from those of genetics. For example, if a person's level of intelligence is similar to that of their parents, is that similarity due to genetic factors passed down from parent to child, to shared environmental factors, or (most likely) to a combination of both? It is clear that both environmental and genetic factors play a part in determining intelligence.

   Task: list every factor related to individual differences named in Sources 2 and 4, and sort them into "inside the person" and "around the person." Which factors are hard to place, and why?

5. Closure5-10 minutes

   Exit ticket: "Name two factors that could make two people in the same class think or act differently, and say why it is hard to tell how much each one matters."

   Teacher note: keep any sharing about students' own imagery, abilities or families voluntary and anonymous, and avoid comparing named students. Intelligence appears in Source 4 only as an example of a complex trait; the lesson makes no comparisons between groups of people. If a student is worried about their own memory, attention or thinking, point them to a school counselor or another trusted adult.

Differentiation Strategies

Assessment Guidance

1. Question 1 of 20 · Multiple Choice

   In Source 1, paragraph 1, why does James wish English could say "it thinks" the way it says "it rains"?

   ATo show that thinking is caused by the weather BTo state that thought goes on with the fewest assumptions CTo prove that animals think in the same way people do DTo argue that only trained psychologists can think clearly

2. Question 2 of 20 · Multiple Choice

   James lists "thought is always changing" and "thought is sensibly continuous" as two characters. Which experience shows both at once?

   ARepeating the same word until it loses its meaning BFalling asleep and waking with no sense of time passing CA daydream drifting from lunch to a song to a friend DSolving the same arithmetic problem twice in a row

3. Question 3 of 20 · Multiple Choice

   Source 1 says "every thought tends to be part of a personal consciousness." What problem does this create for psychologists who study thought?

   AThoughts can be measured only with expensive equipment BThought is the same in everyone, so differences cannot be found CPersonal thoughts are too private to be worth studying DThought must be studied through reports or behavior

4. Question 4 of 20 · Multiple Choice

   In Source 2, paragraph 1, the four travellers bring home very different accounts of one tour. What does James say explains the difference?

   AEach picked out what suited his own interest BSome travellers had better eyesight than others did CThey visited different countries on separate tours DOnly one of the travellers had kept a written diary

5. Question 5 of 20 · Multiple Choice

   According to Source 2, paragraph 1, what largely determines which experiences a person has?

   AHow long the person has lived in one place BThe person's habits of attention CThe number of different objects present DHow many times an object appears

6. Question 6 of 20 · Multiple Choice

   What does James mean in Source 2, paragraph 4 by calling the mind "a theatre of simultaneous possibilities"?

   AThe mind performs best in front of an audience BThought is mostly imagination and has little to do with reality CEveryone's mind contains exactly the same possibilities DMany thoughts are possible at once; some are chosen

7. Question 7 of 20 · Multiple Choice

   In Source 3, Galton asked every correspondent to think of the same kind of object, "your breakfast-table as you sat down to it this morning." Why is a common, familiar object a good choice?

   AEveryone finds breakfast an interesting subject BIt makes answers easier to compare CIt guarantees that every answer will be accurate DIt lets Galton check the real tables afterward

8. Question 8 of 20 · Multiple Choice

   What did Galton first find among "men of science" in Source 3, paragraph 7?

   AMost said mental imagery was unknown to them BMost described images clearer than real scenes CMost refused to answer any of his questions DMost said that imagery came only in dreams

9. Question 9 of 20 · Multiple Choice

   In Source 3, paragraph 8, Galton "pressed and cross-questioned" people while "professing myself to be incredulous." What was this method checking?

   AWhether answers held up when he doubted them BWhether their eyesight was normal for their age CWhether they had read about imagery before DWhether they were scientists or members of the public

10. Question 10 of 20 · Multiple Choice

    According to Source 4, paragraph 2, why is intelligence challenging to study?

    AIt can be defined and measured in different ways BIt changes completely from one day to the next CIt is found in only a small number of people DIt can be measured only after a person is an adult

11. Question 11 of 20 · Multiple Choice

    What have genetic studies of intelligence found, according to Source 4, paragraph 3?

    AOne gene controls most of the differences between people BGenes have no influence on intelligence at all CTwins always have exactly the same level of intelligence DMany genes likely play a part, each with a small effect

12. Question 12 of 20 · Multiple Choice

    Source 4, paragraph 4 asks why a person's intelligence might be similar to their parents'. What answer does it give?

    AShared genes alone, since parents pass on their DNA BShared environment alone, since families live together CMost likely a combination of genes and environment DNeither, since the similarity is only a coincidence

13. Question 13 of 20 · Multiple Choice

    Use the invented data in Source 5, paragraph 3. What is the mean number of details recalled by the six volunteers who draw, paint or design 2 or more hours a week?

    A14 B85 C14.2 D12.3

14. Question 14 of 20 · Multiple Choice

    The team in Source 5, paragraph 4 says 12 volunteers are "far too few" to say how common each kind of imagery is. Why?

    ASmall samples cannot be described with a mean BOne or two people can shift the shares a lot CImagery can be measured only in very large groups DTwelve people would all give the same rating

15. Question 15 of 20 · Short Answer

    Use Source 5, paragraph 3. Compute the mean recall of the six volunteers who draw 1 hour a week or less. Compare it with the mean for the six who draw 2 or more hours (question 13) and with the difference between the high- and low-imagery groups in Guided Practice. Which factor is more closely related to recall in these data?

    Show model answer

16. Question 16 of 20 · Short Answer

    Use Source 5, paragraph 3. Compute the overall mean number of details recalled. How many volunteers recalled more than the mean, and what range of imagery ratings did they give?

    Show model answer

17. Question 17 of 20 · Short Answer

    An invented article says: "Reading skill is 60% genetic, so how well a child reads is mostly fixed at birth." Using Source 4, explain two problems with this claim.

    Show model answer

18. Question 18 of 20 · Short Answer

    Explain how Source 1 and Source 3 together show why thought is hard to study scientifically. Quote each source once.

    Show model answer

19. Question 19 of 20 · Short Answer

    Two siblings grew up in the same home but differ in what they notice and remember. Using one factor from Source 2 and two from Source 4, explain how they could come to differ.

    Show model answer

20. Question 20 of 20 · Short Answer

    Use one example from this lesson to explain why no single factor explains a behavior, and why that matters when people talk about individual differences.

    Show model answer

These standards connect to D2.Psy.8.9-12: prerequisites to review first, parallel standards at the same level, and next steps that build on it.

Standard text: National Council for the Social Studies (NCSS), The College, Career, and Civic Life (C3) Framework for Social Studies State Standards: Guidance for Enhancing the Rigor of K-12 Civics, Economics, Geography, and History (Silver Spring, MD: NCSS, 2013). NCSS was not involved in the production of this lesson and does not endorse it.