D2.Psy.15.9-12: Using Existing Evidence to Formulate Conclusions About Psychological Phenomena
In plain English: D2.Psy.15.9-12 is the C3 Framework psychology indicator for grades 9-12 that asks students to use existing evidence and formulate conclusions about psychological phenomena. Students weigh an original study, a later review and new data, then write conclusions that fit the evidence: scoped to what was studied, worded with the right confidence, and honest about limits.
Use existing evidence and formulate conclusions about psychological phenomena.
C3 Framework for Social Studies (NCSS) · Dimension 2: Applying Disciplinary Concepts and Tools · Discipline: Psychology · Critical Thinking: Themes, Sources, and Evidence · Official standard
D2.Psy.15.9-12 asks students to use existing evidence and formulate conclusions about psychological phenomena. Using evidence means going back to what studies actually measured and found; formulating a conclusion means stating what that evidence supports, for whom, under what conditions, and with how much confidence.
This lesson follows one popular idea, that a little stress improves performance, back to the 1908 study by Yerkes and Dodson that it is usually traced to. Students read the original method, results and conclusions, an SVHS summary of a 1994 review showing how later writers changed the claim, an invented viral post, and an invented puzzle study with invented data. They write scoped, calibrated conclusions and compare them with the popular version.
Learning Objectives
By the end of this lesson, students will be able to:
Identify what an original study measured and found, using quotations from the source
Formulate a conclusion that is supported, scoped and calibrated to the strength of the evidence
Explain how a contradiction between results can lead to a new test and a better conclusion
Compare a popular claim with the existing evidence and name each leap it makes
Interpret means from a data set and state a conclusion with its limits
Prior Knowledge Required
Students should already be comfortable with:
Experiments, random assignment and samples D2.Psy.1.9-12
Interpreting research results D2.Psy.3.9-12
Means and the idea of a standard deviation as spread D2.Psy.6.9-12
Generating research questions from sources D2.Psy.14.9-12
"You may have heard that 'a little stress helps you perform better.' Do you believe it? Write what evidence would convince you, and what evidence would change your mind."
Take a quick show of hands: agree, disagree, not sure. Record the evidence students say they would need. Most will name personal experience; ask what personal experience can and cannot show. Tell students that today they will go back to the study this saying is usually traced to and see what it really found.
Direct Instruction20 minutes
Evidence and conclusions.Existing evidence is what earlier studies, records and data already show. A conclusion is a statement of what that evidence supports. A good conclusion is: supported (every part rests on evidence you can point to), scoped (it says who or what was studied and under what conditions), calibrated (its confidence words, such as suggests, shows or proves, match the strength of the evidence), and complete (it fits all the relevant evidence, not only the parts that agree, and it names the main limits).
Matching confidence words to evidence (guide written for this page)
Evidence
Fitting wording
Example
One small study, or one group only
suggests, is consistent with
One small study suggests that ...
Several studies with different samples that agree
shows, supports
Several studies with different samples found that ...
Studies that disagree, or a review that finds the claim was changed over time
is mixed, is not settled
The evidence on this question is mixed ...
Logic or definitions, not evidence about people
follows from (proofs are for mathematics)
Psychology rarely proves; it supports
Read Source 1. Robert Yerkes and John Dodson worked with dancing mice, the laboratory mice Yerkes was studying at the time (paragraph 1). Each mouse had to learn to choose a white box over a black one, and a wrong choice brought an electric shock of a set strength. Teacher note: electric shocks to animals were common in 1908 laboratories. Today, animal research funded by the U.S. Public Health Service must first be reviewed by an Institutional Animal Care and Use Committee, which weighs the animals' welfare before a study can begin.
1In connection with a study of various aspects of the modifiability of behavior in the dancing mouse a need for definite knowledge concerning the relation of strength of stimulus to rate of learning arose. [...]
2The habit whose formation we attempted to study quantitatively, with respect to the strength of the stimulus which favored its formation, may be described as the white-black discrimination habit. Of the mice which served as subjects in the investigation it was demanded that they choose and enter one of two boxes or passage-ways. One of the boxes was white; the other black. No matter what their relative positions, the subject was required to choose the white one. Attempts to enter the black box resulted in the receipt of a disagreeable electric shock. It was our task to discover (1) whether the strength of this electric stimulus influences the rapidity with which dancers acquire the habit of avoiding the black passage-way, and if so, (2) what particular strength of stimulus is most favorable to the acquisition of this habit.
[...]
3[...] Inasmuch as the training under the conditions of set I required a great deal of time, we decided to shorten the necessary period of training by making the two electric boxes very different in brightness, and the discrimination correspondingly easy. [...]
4With each of the five strengths of stimuli which were used in set II two pairs of mice were trained, as in the case of set I. [...] Casual examination of these tables reveals the fact that in general the rapidity of learning in this set of experiments increased as the strength of the stimulus increased. The weakest stimulus (135 units) gave the slowest rate of learning; the strongest stimulus (420 units), the most rapid.
5The results of the second set of experiments contradict those of the first set. What does this mean? It occurred to us that the apparent contradiction might be due to the fact that discrimination was much easier in the experiments of set II than in those of set I. To test this matter we planned to use in our third set of experiments a condition of visual discrimination which should be extremely difficult for the mice. [...]
6For the experiments of set III only one pair of dancers was trained with any given strength of stimulus. The results, however, are not less conclusive than those of the other sets of experiments because of the smaller number of individuals used. [...]
7In set III both the weak and the strong stimuli were less favorable to the acquirement of the habit than the intermediate stimulus of 195 units. [...]
Robert M. Yerkes and John D. Dodson, Source 1: Yerkes and Dodson's experiment with dancing mice (1908) (1908). Public domain (published 1908). Source text.
Using evidence to explain a contradiction: Source 1, paragraph 5
The results of set II "contradict those of the first set." The authors suspected that "discrimination was much easier" in set II, so they ran set III with a task that "should be extremely difficult for the mice."
Result: Conclusion from the evidence: a contradiction between two sets is a reason to look for a difference in conditions and to test it, not to drop one result. Here the suspected difference was task difficulty.
A scoped conclusion: Source 1, paragraph 7
In set III, the hardest task, "both the weak and the strong stimuli were less favorable" than the intermediate stimulus of 195 units.
Result: Scoped conclusion: In dancing mice learning a very hard white-black discrimination, a medium shock (195 units) led to faster learning than weaker or stronger shocks. Not supported by this alone: any claim about people, about stress in general, or about other tasks.
Calibrating confidence: Source 1, paragraph 6
Set III used "only one pair of dancers" for each strength, yet the authors say the results are "not less conclusive."
Result: With two mice per strength, the fitting wording is "suggests," not "proves." Students can still use the result, but should say it rests on very few animals and needs repeating.
Then read Source 2, the authors' own conclusions. Notice how often they limit their claims.
1From the data of the various tables we draw the following conclusions: [...]
22. The relation of the strength of electrical stimulus to rapidity of learning or habit-formation depends upon the difficultness of the habit, or, in the case of our experiments, upon the conditions of visual discrimination.
33. When the boxes which are to be discriminated between differ very greatly in brightness, and discrimination is easy, the rapidity of learning increases as the strength of the electrical stimulus is increased from the threshold of stimulation to the point of harmful intensity. This is indicated by curve II. Our results do not represent, in this instance, the point at which the rapidity of learning begins to decrease, for we did not care to subject our animals to injurious stimulation. We therefore present this conclusion tentatively, subject to correction in the light of future research. [...] The irregularity of curve II, in that it rises slightly for the strength 375, is due, doubtless, to the small numbers of animals used in the experiments. Had we trained ten mice with each strength of stimulus instead of four the curve probably would have fallen regularly.
44. When the boxes differ only slightly in brightness and discrimination is extremely difficult the rapidity of learning at first rapidly increases as the strength of the stimulus is increased from the threshold, but, beyond an intensity of stimulation which is soon reached, it begins to decrease. Both weak stimuli and strong stimuli result in slow habit-formation. [...]
55. [...] This leads us to infer that an easily acquired habit, that is one which does not demand difficult sense discriminations or complex associations, may readily be formed under strong stimulation, whereas a difficult habit may be acquired readily only under relatively weak stimulation. [...]
6Attention should be called to the fact that since only three strengths of stimulus were used for the experiments of set I, it is possible that the most favorable strength of stimulation was not discovered. [...]
7Naturally we do not propose to rest the conclusions which have just been formulated upon our study of the mouse alone. We shall now repeat our experiments, in the light of the experience which has been gained, with other animals.
Robert M. Yerkes and John D. Dodson, Source 2: Yerkes and Dodson's conclusions (1908) (1908). Public domain (published 1908). Source text.
Guided Practice15 minutes
Read Source 5 together. It is an SVHS summary, written for this page, of a 1994 review article by the psychologist Karl Halvor Teigen, checked against the article's published abstract. Then read Source 3, an invented viral post.
1SVHS summary, written for this page, of a review article: Karl Halvor Teigen, "Yerkes-Dodson: A Law for all Seasons," Theory & Psychology 4, no. 4 (1994): 525-547. The summary is based on the article's published abstract.
2Teigen traced how the Yerkes-Dodson law was described from 1908 onward. In its original form, he writes, the law described how stimulus strength relates to habit-formation for tasks that differ in how hard the discrimination is.
3Later researchers and textbook authors, he finds, restated it in many ways: as the effect of punishment, reward, motivation, drive, arousal, anxiety, tension or stress on learning, performance, problem-solving, coping or memory. The task variable was renamed difficulty, complexity or novelty, or was left out altogether.
4Teigen notes that these changes are seldom discussed openly and are often wrongly credited to Yerkes and Dodson themselves. He sees the many versions as reflecting changing ideas about learning, motivation and emotion, and argues that the law's flexibility also reflects how vague some basic psychological concepts in these areas are.
SVHS (summary of a published abstract), Source 5: How the Yerkes-Dodson law changed over time (SVHS summary of Teigen, 1994) (2026). Original passage written for this page.
1Invented social media post, written for this page. It is an example of a misleading claim, not advice.
2"SCIENCE SAYS STRESS MAKES YOU BETTER. The Yerkes-Dodson law proves that everyone performs best at medium stress. So before your next exam, turn up the pressure: give yourself a scary deadline and tell yourself everything depends on this one test. A law that has been around for more than 100 years can't be wrong. Share this with someone who is too relaxed!"
3The post has 48,000 likes. It does not link to any study.
SVHS (invented scenario), Source 3: A viral post about stress (invented scenario) (2026). Original passage written for this page.
Compare. In two columns, list what the 1908 study measured and studied, and what the post claims.
Count the leaps. How many separate changes does the post make between the evidence and its claim? Use Source 5 to show that these changes happened over time and are not in the 1908 article.
Check the confidence words. The post says the law "proves" something. Which row of the confidence table fits the evidence better?
Draft. Pairs write one sentence that says what the 1908 evidence does support.
A second author has gone further. In a 2015 article on workplace stress, "From Law to Folklore: Work Stress and the Yerkes-Dodson Law," Martin Corbett argues that the evidence for the law as a rule about human stress does not hold up and that managers should not try to raise performance by raising stress (Journal of Managerial Psychology 30, no. 6, pp. 741-752; checked against the published abstract). Treat this as one author's argument to weigh, not as a final verdict.
Independent Practice15 minutes
Students read Source 4 on their own. It is an invented study with invented data, written for this page to practice drawing conclusions from numbers. Because it is invented, it is not evidence about real people; it is practice material. It is also limited by design: adults from one city, word puzzles only, and 30 people per condition.
1Invented study with invented data, written for this page. A researcher recruited 90 adult volunteers and randomly assigned 30 to each of three pressure conditions. In the low-pressure condition, no clock was shown. In the medium-pressure condition, a timer counted down on the screen. In the high-pressure condition, the timer was shown and volunteers were told that an observer was rating their speed.
2Every volunteer then tried 10 easy puzzles and 10 hard puzzles. The researcher counted how many of each kind they solved.
3Average puzzles solved out of 10, with the standard deviation in parentheses. Easy puzzles: low pressure 7.1 (1.6), medium pressure 7.9 (1.4), high pressure 8.2 (1.5). Hard puzzles: low pressure 3.8 (1.9), medium pressure 4.6 (2.0), high pressure 3.2 (2.1).
4After the session, every volunteer was told the real purpose of the study, and none of the ratings were kept. The researcher notes that the volunteers were adults from one city and that the puzzles were word puzzles only.
SVHS (invented scenario), Source 4: A puzzle study under pressure (invented study with invented data) (2026). Original passage written for this page.
Task: (1) For each kind of puzzle, find which condition had the highest average. (2) Write one conclusion for easy puzzles and one for hard puzzles, each scoped (who, what task) and calibrated (one confidence word from the table). (3) Name one limit from paragraph 4 and say how it changes your wording. Any follow-up study is planned on paper only. Sources 1-5 are used again in the quiz and homework.
Closure5-10 minutes
Exit ticket: "Rewrite the claim 'A little stress helps you perform better' so that it fits the evidence from today. Then name the one piece of evidence you would most want next."
Teacher notes. (1) Source 3 is an invented, misleading post; do not let students treat its advice as guidance. Pressure and stress affect people differently, and students who feel very stressed about tests should talk to a trusted adult or school counselor. (2) Source 4 and all its numbers are invented. (3) The 1908 study used electric shocks on mice; the page notes today's animal welfare review.
Differentiation Strategies
For Struggling Students
Give a conclusion frame: "In [who], [what] was linked to [result]. This evidence [confidence word] because [limit]."
Pre-highlight the result sentence in each paragraph of Source 1
In Independent Practice, have students write the easy-puzzle conclusion only, then compare with a partner
For Advanced Students
Estimate how large the hard-puzzle difference between medium and high pressure is compared with the standard deviations, and say what that means for confidence
Compare Teigen's account (Source 5) with Corbett's argument and write a conclusion that fairly represents both
Design, on paper only, a follow-up that would test whether the task-difficulty pattern in Source 1 holds for people
Assessment Guidance
What to Look For
Strong conclusions quote or cite the evidence with paragraph numbers, say who was studied and under what conditions, use confidence words that match the evidence, and name at least one limit. Watch for conclusions that move from mice to people, from shock strength to "stress," or from one task to all tasks, and for the word "proves." Students should also treat Source 4 as invented practice data, not as evidence about real people.
02
Classroom Activities
3 Activities
1
Evidence Cards: How Much Does Each One Show?
15 minGroups of 3-4
Each group gets 6 Evidence Cards and one question: Is the best level of pressure the same for every task? Groups sort the cards twice, once for what each shows about mice and once for what it shows about people, from strongest to weakest, and write one reason for each placement.
The 6 Evidence Cards
Yerkes and Dodson, set III (Source 1, paragraph 7): on a very hard task, a medium shock beat weaker and stronger ones; one pair of mice per strength.
Yerkes and Dodson, set II (Source 1, paragraph 4): on an easy task, learning was faster as the shock got stronger; only a few mice per strength.
Teigen's review (Source 5): later writers restated the result as a claim about stress and often dropped the task.
The viral post (Source 3): "everyone performs best at medium stress."
A friend's story: "I always do better on tests when I'm a little nervous."
The puzzle study (Source 4): invented data showing a pattern like Yerkes and Dodson's.
Answer Key
For mice: cards 1 and 2 are the only direct evidence; together they suggest that the best shock strength depends on task difficulty, but each rests on very few animals. Card 3 helps read them correctly. Cards 4-6 say nothing about mice.
For people: none of the cards is real evidence about people. Card 3 shows that the claim about people was added later; card 5 is one person's experience; card 6 is invented; card 4 has no evidence at all. The fair conclusion is that this set of cards cannot answer the question for people.
Debrief Questions
Which card would most people find most convincing, and why is it not the strongest?
What kind of new evidence would move a card into the "people" column?
2
Conclusion Tuner: Six Drafts
15 minPairs
Pairs get 6 draft conclusions about the 1908 study. For each, they name the problem (goes beyond the species, changes the variable, wrong confidence, ignores some evidence, claims too little, or no scope) and rewrite it so that it fits Sources 1 and 2.
The 6 Drafts
"Yerkes and Dodson showed that athletes play best when they feel moderately excited."
"Medium anxiety is best for learning."
"The 1908 study proves that strong shocks speed learning."
"In set II, stronger shocks led to faster learning, so strong shocks are best for all tasks."
"The 1908 study tells us nothing at all."
"Shock strength mattered."
Answer Key
1: goes beyond the species and changes the variable (shock strength to excitement). Rewrite: in dancing mice, the shock strength that led to the fastest learning depended on how hard the discrimination was.
2: changes the variable (shock to anxiety) and drops the task.
3: wrong confidence and ignores set III, where strong shocks were less favorable.
4: ignores evidence from the harder tasks.
5: claims too little: the study gives real evidence about mice on this task.
6: no scope: say which animals, which task and which result.
Variation: Your Own Draft
Each pair writes one flawed conclusion about Source 4 and trades it with another pair to tune.
3
Answering the Viral Post
15 minGroups of 3
Groups write a short reply to the invented post in Source 3 using a Claim, Evidence and Reasoning organizer. The reply must cite at least three sources with paragraph numbers, use one confidence word from the Direct Instruction table, and end with a conclusion the evidence supports. Replies are written on paper and shared in class only; nothing is posted online.
Organizer
Claim: what the post gets wrong, in one sentence.
Evidence: what the 1908 study measured and found (Sources 1 and 2), and how the claim changed later (Source 5).
Reasoning: why that evidence does not support the post's claim about exams and everyone.
Conclusion: what can fairly be said.
Gallery Check
Groups swap replies and check one thing: does every part of the conclusion rest on a cited source?
03
Diagrams & Visual Aids
1 diagrams
Diagram 1: Source 4 Results (Invented Data)
Average puzzles solved out of 10 in the invented study in Source 4, 30 volunteers per condition, drawn to scale. On easy puzzles the average rises with pressure; on hard puzzles it is highest at medium pressure. The data are invented for practice and are not evidence about real people.
04
Homework Assignment
~30 min
Homework: From Evidence to Conclusions
Directions: Part 1 uses Sources 2, 4 and 5. Quote every source you use with its paragraph number. Part 2 asks you to formulate conclusions about new evidence and to plan a study on paper only: do not run it on anyone.
Part 1: Conclusions from the Sources (Problems 1-3)
Source 2, paragraph 4 describes what happened when discrimination was "extremely difficult." State the conclusion in your own words, scoped to the animals and task, and name one thing it does not tell us.
In Source 4, find the average number solved across the three conditions for easy puzzles and for hard puzzles (round to one decimal place). Show your work. What conclusion about puzzle difficulty do these two averages support, and how confident should you be, given that the data are invented and come from one city?
Using Source 5, describe two ways the Yerkes-Dodson law was changed by later writers. Then explain why a student citing "the Yerkes-Dodson law" as existing evidence should go back to the 1908 article.
Part 2: New Evidence and a Plan (Problems 4-6)
Invented case: a survey of 200 students found that those who said they felt "a little nervous" before tests had higher average grades than those who said "very calm" or "very nervous." Formulate the conclusion this survey supports, and give one other explanation for the pattern that the survey cannot rule out.
Plan, on paper only, a study with adult volunteers that would test whether the best level of pressure depends on task difficulty in people. Use only mild pressure (such as a visible timer), describe consent and what volunteers are told afterward, and state what result would support the idea.
Write one paragraph that answers the question "Does a little stress help you perform better?" using at least three sources from this lesson with paragraph numbers. Use one confidence word from the Direct Instruction table and name the most important limit of the evidence.
Rubric
Criterion
Full Credit (2 pts)
Partial Credit (1 pt)
No Credit (0 pts)
Use of evidence
Every claim cites a source and paragraph and describes what was actually measured
Sources cited without paragraph numbers, or one claim unsupported
No evidence used
Conclusions
Conclusions are scoped (who, what task) and use confidence words that fit the evidence
Conclusions mostly fit but one overreaches or lacks scope
Conclusions overreach or are missing
Data and limits
Computations are correct and limits of small or invented samples are named
Computations correct but limits missing, or one error
Computations missing or wrong
Study plan
Plan uses mild, ethical pressure with consent and a debrief, on paper only, and states a supporting result
Plan addresses some of these
No plan, or a plan that would harm or deceive participants
05
Quiz: 20 Questions
Interactive, with answers
Instructions
Sources 1 and 2 are printed in Direct Instruction, Sources 5 and 3 in Guided Practice, and Source 4 in Independent Practice. Source 1 is used in Questions 1-4, 13 and 15; Source 2 in Questions 4-7, 9, 16, 18 and 19; Source 3 in Questions 9 and 18; Source 4 in Questions 10-12 and 17; and Source 5 in Questions 8, 18 and 19. Questions 14 and 20 need no printed source. Questions 1-14 are multiple choice; 15-20 are short answer.
Multiple choice: pick an option to check it. Short answer: write your answer, then reveal the model answer.
0 of 20 answered · 0 correct
Question 1 of 20 · Multiple Choice
According to Source 1, paragraph 2, which box did the mice have to learn to choose?
Answer: B
The authors write: "No matter what their relative positions, the subject was required to choose the white one." Entering the black box brought a shock, so A reverses the task. C and D are not in the source; position did not matter.
Question 2 of 20 · Multiple Choice
According to Source 1, paragraph 4, which stimulus strength gave the slowest learning in set II?
Answer: A
"The weakest stimulus (135 units) gave the slowest rate of learning; the strongest stimulus (420 units), the most rapid." D reverses slowest and fastest. B is the most favorable strength in set III (paragraph 7), a mix-up between sets. C is not given for set II in the passage.
Question 3 of 20 · Multiple Choice
According to Source 1, paragraph 3, why did the researchers make the two boxes very different in brightness for set II?
Answer: D
They write that set I "required a great deal of time," so "we decided to shorten the necessary period of training" by making the boxes very different. B is a sequence error: the difficulty idea came after set II's results and was tested in set III (paragraph 5). A and C are not in the source.
Question 4 of 20 · Multiple Choice
How many mice were trained with each stimulus strength in set II?
Answer: C
Paragraph 4 says "two pairs of mice were trained" with each strength, which is four; Source 2, paragraph 3 agrees ("instead of four"). A counts pairs as mice, or uses set III's single pair. B is the number the authors wished they had used. D is not in the passage.
Question 5 of 20 · Multiple Choice
According to Source 2, paragraph 3, why do the authors present conclusion 3 "tentatively"?
Answer: A
"Our results do not represent ... the point at which the rapidity of learning begins to decrease, for we did not care to subject our animals to injurious stimulation." B describes the limit they note for set I (paragraph 6), not set II. C is not in the passage. D misreads the contradiction, which was between sets I and II.
Question 6 of 20 · Multiple Choice
In Source 2, paragraph 3, how do the authors explain the slight rise in curve II at the strength 375?
Answer: C
They write that the irregularity "is due, doubtless, to the small numbers of animals used," and that ten mice per strength would probably have given a regular curve. D is wrong because set II was the easy task. A and B are not given as explanations.
Question 7 of 20 · Multiple Choice
According to Source 2, paragraph 6, what limit in their own evidence do the authors point out?
Answer: B
"Since only three strengths of stimulus were used for the experiments of set I, it is possible that the most favorable strength of stimulation was not discovered," so the best strength for set I may not be among the three they tried. A is a real limit (Source 1, paragraph 6) but not the one named here. C was a deliberate condition, not a weakness. D is not in the passage.
Question 8 of 20 · Multiple Choice
According to Source 5, what did later writers often leave out when they restated the Yerkes-Dodson law?
Answer: D
Source 5, paragraph 3: the task variable "was renamed difficulty, complexity or novelty, or was left out altogether." A reverses the change: stress and arousal were added by later writers, not left out. B and C are not in the summary.
Question 9 of 20 · Multiple Choice
The post in Source 3 says "everyone performs best at medium stress." Which leap does the word "everyone" make beyond Sources 1 and 2?
Answer: A
The 1908 subjects were dancing mice, and the authors said they did not rest their conclusions on "the mouse alone" (Source 2, paragraph 7) but planned more animal studies; no people were tested. B, C and D describe comparisons inside the 1908 study, not the jump to people.
Question 10 of 20 · Multiple Choice
In Source 4, paragraph 3, how many more easy puzzles did the high-pressure group solve on average than the low-pressure group?
Answer: C
8.2 - 7.1 = 1.1. A compares high with medium (8.2 - 7.9). B compares medium with low (7.9 - 7.1). D subtracts the hard-puzzle low-pressure average from the easy-puzzle high-pressure average (8.2 - 3.8), mixing the two puzzle types.
Question 11 of 20 · Multiple Choice
Which conclusion best fits the invented data in Source 4?
Answer: B
On easy puzzles the high-pressure average was highest (8.2); on hard puzzles the medium-pressure average was highest (4.6), so the best condition depended on puzzle difficulty, and "in this sample" keeps the scope. A ignores the hard puzzles, where high pressure was lowest (3.2). C ignores the easy puzzles. D ignores both patterns. The data are invented, so even B describes practice data only.
Question 12 of 20 · Multiple Choice
Which detail in Source 4 lets the researcher say that the pressure conditions caused the differences in this sample?
Answer: D
Paragraph 1: volunteers were "randomly assigned" to the three conditions, so the groups should be alike except for pressure. A is an ethical step, not a design feature that supports cause. B lets the researcher compare puzzle types but does not decide who got which pressure. C is a limit on who the results apply to.
Question 13 of 20 · Multiple Choice
A student writes: "In set III, a medium shock led to the fastest learning for every animal." Which phrase goes beyond Source 1?
Answer: D
Source 1 reports results for dancing mice only, and only two mice per strength in set III (paragraph 6). "For every animal" extends the result to all animals. A, B and C match paragraph 7: in set III, the intermediate stimulus of 195 units was more favorable than weaker or stronger ones.
Question 14 of 20 · Multiple Choice
Which new evidence would do the most to strengthen a conclusion about people and pressure?
Answer: A
Only studies with people can support a conclusion about people, and several tasks would show whether the pattern depends on the task. B would strengthen the conclusion about mice, the error of improving evidence for the wrong group. C measures popularity, not evidence. D adds no new evidence.
Question 15 of 20 · Short Answer
Using Source 1, paragraph 4, write a conclusion about set II that is scoped and calibrated, and name one limit of the evidence.
Model answer: In dancing mice learning an easy white-black discrimination, stronger shocks were linked to faster learning: "in general the rapidity of learning in this set of experiments increased as the strength of the stimulus increased." Because only a few mice were trained with each strength and only one easy task was used, this evidence suggests the pattern but does not show it for other tasks or animals. Rubric: 2 = scoped (mice, easy task), calibrated wording, quotation and a limit; 1 = two or three of these; 0 = fewer.
Question 16 of 20 · Short Answer
Source 2, paragraph 5 begins "This leads us to infer." Explain what this phrase signals about the authors' confidence, restate the inference in your own words, and say whether it is a claim about stress in people.
Model answer: "Infer" signals a step beyond the data: the authors are drawing a general idea from their results, not reporting a measurement. The inference is that an easy habit can be learned well under strong stimulation, while a hard habit is learned well only under relatively weak stimulation. It is not a claim about stress in people: it is about the strength of an electric shock and a discrimination habit in mice, and paragraph 7 says they did not rest their conclusions on "the mouse alone." Rubric: 2 = explains the signal, restates the inference, and correctly says it is about mice and shocks; 1 = two of these; 0 = fewer.
Question 17 of 20 · Short Answer
In Source 4, find how much higher the hard-puzzle average was in the medium-pressure condition than in the low and high conditions. Then formulate a conclusion about hard puzzles and explain why the standard deviations call for careful wording.
Model answer: Medium minus low: 4.6 - 3.8 = 0.8 puzzles. Medium minus high: 4.6 - 3.2 = 1.4 puzzles. Conclusion: in this invented sample of adults, hard word puzzles were solved most often under medium pressure. Both differences are smaller than the standard deviations (about 2 puzzles), so many individuals in different conditions overlapped; with 30 people per condition, the result suggests a pattern but does not settle it, and because the data are invented, it is practice only. Rubric: 2 = both differences correct, a scoped conclusion, and the standard-deviation caution; 1 = differences correct with a weak conclusion; 0 = errors.
Question 18 of 20 · Short Answer
Rewrite the claim in Source 3 so that it fits the evidence. Cite two sources with paragraph numbers.
Model answer: "A 1908 study of dancing mice found that the shock strength that led to the fastest learning depended on how hard the task was (Source 2, paragraph 2); later writers turned this into a claim about human stress (Source 5, paragraph 3), and that version is not what the original study tested." The rewrite drops "everyone," "stress" and "proves," and keeps the task-difficulty part the post leaves out. Rubric: 2 = a rewrite that fits the evidence with two correct citations; 1 = one citation or one remaining overreach; 0 = neither.
Question 19 of 20 · Short Answer
Is it fair to say "Yerkes and Dodson showed that moderate stress improves human performance"? Use Source 2 and Source 5 to explain.
Model answer: No. Yerkes and Dodson studied the strength of electric shocks and how fast dancing mice learned a white-black discrimination, and they found that the best strength depended on task difficulty (Source 2, paragraph 2). They said they would repeat the work "with other animals" (paragraph 7), not people. Source 5 shows that the version about stress, arousal and human performance came from later writers and is "often wrongly credited to Yerkes and Dodson themselves" (paragraph 4). A fair statement credits them with the mouse finding only. Rubric: 2 = no, with evidence from both sources; 1 = one source; 0 = neither.
Question 20 of 20 · Short Answer
Explain the difference between using existing evidence and formulating a conclusion. Use one example from this lesson.
Model answer: Using existing evidence means finding and reading what studies actually measured and found, such as going back to the 1908 article to see that it measured shock strength and learning in mice. Formulating a conclusion means stating what that evidence supports, with its scope and confidence: for example, "In dancing mice, the shock strength that led to the fastest learning depended on task difficulty; the evidence suggests this but rests on few animals." The first step gathers and checks; the second step judges. Rubric: 2 = both terms explained with a correct example; 1 = one term or no example; 0 = neither.
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Frequently Asked Questions
10 Questions
What does D2.Psy.15.9-12 mean?
D2.Psy.15.9-12 asks high school students to use existing evidence and formulate conclusions about psychological phenomena. It is an indicator in the C3 Framework's psychology companion (Appendix B), in the group on critical thinking about themes, sources and evidence. Students go back to what studies actually measured and then state what that evidence supports, for whom and with how much confidence.
What makes a good conclusion in psychology?
A good conclusion is supported by evidence you can point to, scoped to the people or animals and conditions studied, calibrated so that its confidence words match the evidence, and complete, meaning it fits all the relevant evidence and names its main limits. "One small study suggests ..." is often more accurate than "Science proves ...".
What did the original 1908 Yerkes and Dodson study find?
Working with dancing mice, Yerkes and Dodson found that the shock strength that led to the fastest learning of a white-black discrimination depended on how hard the discrimination was: stronger shocks worked best on the easy task, and a medium shock worked best on the very hard task. They used few mice per condition and said they would repeat the work with other animals.
Is the Yerkes-Dodson law about stress?
Not in its original form. A 1994 review by Karl Halvor Teigen, summarized in Source 5, traces how later writers restated it as a claim about arousal, anxiety or stress and often dropped the task-difficulty part. The 1908 study measured electric shock strength and learning in mice.
Why does a D2.Psy.15.9-12 lesson use invented data?
Invented data let students practice reading means and writing conclusions without the page making claims about real people. Source 4 is labeled invented wherever it appears, and the lesson says plainly that it is practice material, not evidence about people.
Is it ethical that the 1908 study used electric shocks on mice?
The page notes that such methods were common in 1908 laboratories and that animal research funded by the U.S. Public Health Service today must first be reviewed by an Institutional Animal Care and Use Committee. Students can discuss how today's review would weigh the animals' welfare; the lesson's own study plans use only mild pressure with adult volunteers, on paper only.
How is D2.Psy.15.9-12 different from D2.Psy.14.9-12?
D2.Psy.14.9-12 is about asking: using sources to generate research questions. D2.Psy.15.9-12 is about answering: using the evidence that already exists to reach a conclusion. A good sequence is to generate a question with 14 and then answer it with 15.
What is a common mistake students make when writing conclusions?
A common mistake is overgeneralizing: moving from the animals, task or variable that was studied to a much broader claim, as in "mice learned faster with a medium shock" becoming "people do best under medium stress." Another is using "proves" for one small study. Ask students to underline the scope words in every conclusion.
Should students use the popular advice to raise their stress before tests?
No. The evidence on this page does not support that advice, and Source 3 is an invented example of a misleading post. Students who feel very stressed about tests should talk to a trusted adult or a school counselor.
How can I assess D2.Psy.15.9-12?
Ask students to write a conclusion from a source they have not seen, then score it on four points: does it cite the evidence, is it scoped, is its confidence calibrated, and does it name a limit? The homework rubric and the Conclusion Tuner activity give ready-made criteria.
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Related Standards
6 standards
These standards connect to D2.Psy.15.9-12: prerequisites to review first, parallel standards at the same level, and next steps that build on it.
Before this lesson
D2.Psy.14.9-12Prerequisite
Use information from different psychological sources to generate research questions
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.
