Chapter 28 — Exercises

Work these without looking back at the chapter first; then check yourself. Items marked † have full worked solutions in the answers appendix. There are no answers in this file. Mix of recall, applied reasoning, evidence interpretation, "spot the overstatement," ethics, and a cold-case extension.

A. Recall and definitions

  1. Define forensic psychology in one sentence, and list the three tasks that make up the bulk of the working field.

  2. † Define criminal profiling, and state the single premise on which the whole practice rests (the assumed relationship between behavior and personality).

  3. Distinguish competency to stand trial from the insanity defense: which is present-tense, which is past-tense, and what does each one decide?

  4. Define modus operandi (MO) and signature, and explain why MO tends to evolve across an offender's crimes while signature is theorized to be more stable.

  5. † Define the Barnum effect (Forer effect) and name three everyday practices (outside criminal justice) that exploit it.

  6. What was the organized/disorganized dichotomy, which FBI unit produced it, and what kind of sample was it originally built from?

  7. State the legal standard for competency to stand trial established by Dusky v. United States (1960), in your own words.

  8. What did the Insanity Defense Reform Act of 1984 change, and what real case prompted it?

B. Applied reasoning

  1. † A profiler delivers a portrait of an unknown offender: "a male in his twenties or thirties, intelligent but underachieving, with unresolved anger and a difficult family history, who likely follows the news coverage of his crime." Identify the features of this statement that make it feel specific while predicting almost nothing. Then rewrite one of its claims as a genuinely falsifiable prediction.

  2. Explain, step by step, why structured/actuarial risk assessment outperforms unstructured clinical judgment. What book-wide principle (from Chapter 1, previewing Chapter 31) does this illustrate?

  3. A risk-assessment instrument places a defendant in a category whose members reoffend at a certain rate over five years. A prosecutor says, "The test proves he will be violent if released." Identify the error (connect it to the prosecutor's fallacy, Chapter 9) and state what the instrument can honestly support.

  4. † A behavioral analyst is asked whether three burglary-assaults are the work of one offender. Using the MO/signature distinction, explain what kind of behavior would link the crimes and what the honest strength of that conclusion is (which verb?).

  5. Why is geographic profiling more defensible than psychological offender profiling? Name the specific properties of its inputs and outputs that make it more testable.

  6. A defendant is found incompetent to stand trial. Describe what typically happens next, and explain why this is not the same as an acquittal.

  7. Explain why the insanity defense produces "battles of the experts" more often than competency evaluations do. (Hint: past vs. present mental state, and what can be directly examined.)

C. Evidence interpretation

  1. † Re-read Figure 28.1 ("MO versus signature at three scenes"). State which recorded behaviors are MO and which is the candidate signature, what the figure concludes about linkage, and three reasons even the linkage conclusion is not certain.

  2. Re-read Figure 28.2 ("Barnum statement vs. specific, testable prediction"). Explain in your own words the single property that separates the two columns, and why a statement that "cannot be wrong cannot be informative."

  3. An after-action report praises a profile because, once the offender was caught, "the profile matched him almost exactly." Name the two cognitive biases (one from §28.5, one from Chapter 31) that make such after-the-fact matching nearly worthless as evidence the profile worked.

  4. A profiler's report on an unknown offender includes the line: "subject is likely to be employed in a position below his true intellectual capacity." Explain why this is a classic Barnum-style claim — i.e., how it manages to feel insightful while being nearly impossible to disconfirm.

D. Spot the overstatement / junk-science alert

  1. † A trial witness testifies: "Based on my behavioral analysis of the crime scene, the defendant fits the profile of the offender, and in my opinion he committed this crime." Identify the specific overstatement (what is being claimed that profiling cannot support), explain why courts generally do not admit profiling as proof of identity (Chapter 5), and give the most a behavioral analyst could defensibly say.

  2. A documentary recounts three cases in which "the profile was uncannily accurate" and concludes that profiling is a proven forensic method. Name the reasoning error (the survivorship/selective-storytelling trap) and state what kind of evidence would be needed to establish the method's validity.

  3. A television detective glances at a body and announces the killer's age, occupation, marital status, and car. Using §28.1 and §28.4, give two reasons this is a fantasy version of an activity that, even done seriously, cannot deliver that.

  4. "Profiling helped catch him, so it works." Explain why a correct arrest at the end of an investigation does not show the profile worked as a method — and how a profile can be present at the end yet have done harm in the middle.

E. Ethics and reasoning

  1. † A profile of an unknown offender describes "a lone, opportunistic stranger." Investigators begin focusing exclusively on transients and outsiders and stop scrutinizing the victim's close associates. Using the Cognitive-Bias Watch in §28.5 (and previewing Chapter 31), explain the danger (tunnel vision) and describe how a profile should be treated instead.

  2. You are a forensic psychologist asked by a retaining attorney to "find that the defendant is incompetent" before you have evaluated him. Explain why this framing is an ethical problem, and what your obligation actually is. (Tie to the hired-gun problem, previewed for Chapter 30.)

  3. An innocent man is publicly treated as a suspect largely because he matches a profile (think of Richard Jewell, case-study-01). Explain the specific harm a confident, wrong profile can do that a merely useless one cannot, and why "he fit the profile" is not evidence of guilt.

  4. Why is it important, ethically and scientifically, that forensic psychology's genuine products (competency, sanity, risk) not be tarred with profiling's weak validity — and, conversely, that profiling not borrow the credibility of those genuine products?

F. Synthesis and validity spectrum

  1. † Place these four on the NAS 2009 / PCAST 2016 validity spectrum (strong → discredited), justifying each: single-source nuclear DNA (Chapter 7); structured violence risk assessment (this chapter); predictive criminal profiling (this chapter); bite-mark comparison (Chapter 16). Explain what property profiling lacks that even the contested physical-comparison methods at least attempt.

  2. Explain how this chapter is the book's purest example of the CSI effect (Theme 4) — the over-selling of a forensic product — and identify the second theme the chapter most strongly advances, with one sentence of justification.

  3. In one paragraph, explain the through-line that distinguishes psychology's genuine investigative contributions (§28.6) from profiling: what do competency, sanity, risk, threat assessment, geographic profiling, and linkage analysis all have that predictive profiling does not?

G. Cold-case extension

  1. † Cold Case. Using only what the chapter's Case File establishes, write the entry you would add to the Mill Creek workbook (Appendix I) about the "lone drifter/stranger" profile. State (a) the honest status of this "evidence," (b) the direction in which the profile pointed and whom it pointed away from, (c) why it excludes and includes no one, and (d) the methodological lesson it teaches about how a profile should be used.

  2. Cold Case extension. The profile pointed away from Roy Keller. List two real evidence types from earlier chapters that later pointed back toward him, and explain why those constrain the case in a way the profile never could. (Do not assert a final conclusion — state only what each piece supports.)

  3. Cold Case, integrative. Suppose an investigator argues, "The profile was wrong, so we should ignore behavioral science entirely in this case." Identify what genuine psychological contributions (from §28.6) could still help the Mill Creek investigation, and explain why rejecting profiling does not mean rejecting the validated parts of the field.

H. Short writing

  1. In 150–200 words, explain to a juror why a criminal profile that "feels" remarkably accurate is not, for that reason, good evidence — using the Barnum effect and the idea of falsifiability.

  2. † In 150–200 words, contrast the validity foundations of competency-to-stand-trial assessment with those of predictive criminal profiling: what does each rest on, what can be examined in each, where is each strong or weak, and how does each fare under the admissibility standards of Chapter 5?