AP Psychology: The Brain (Drill 4)

Question 1. A neurologist studies a patient injured in a car accident. After the injury, the patient struggles to stay alert during the day and cannot maintain a normal sleep-wake cycle, even though his movement and sensory perception are intact. Which brain structure is most likely damaged?

• A) The limbic system, which governs emotional memory and fear responses
• B) The reticular activating system, which regulates arousal and alertness ✓
• C) The corpus callosum, which transfers information between the two cerebral hemispheres
• D) The cerebellum, which coordinates voluntary motor movements and balance

Explanation: The reticular activating system (RAS), located in the brainstem, is specifically responsible for regulating arousal, alertness, and the sleep-wake cycle, exactly the functions this patient has lost. The patient's intact movement and sensation rule out the cerebellum and sensory cortices. (A) describes a real system, but the limbic system governs emotion and fear rather than wakefulness; it does not address what the question asks. (C) is also factually accurate but wrong here, corpus callosum damage typically produces split-brain phenomena, not alertness deficits. [Practice 1]

Question 2. A researcher presents participants with images of threatening faces while recording brain activity. One structure consistently shows heightened activation in response to the threatening images but not to neutral ones. Which structure is most likely responsible for this pattern?

• A) The hippocampus, which consolidates explicit memories into long-term storage
• B) The hypothalamus, which regulates hunger, thirst, and body temperature
• C) The amygdala, which evaluates emotional significance and triggers fear responses ✓
• D) The thalamus, which relays sensory information to the appropriate cortical areas

Explanation: The amygdala responds with heightened activation to emotionally charged or threatening stimuli and initiates fear-related responses, the pattern the study describes. Structures that handle homeostasis or general memory consolidation would not show this selective response to threat. (A) is accurate as far as it goes, the hippocampus does encode memories of fearful events, but it does not explain selective activation to threatening versus neutral faces, which is the specific finding. (D) is also true, but thalamic activation would not distinguish threatening from neutral stimuli; the thalamus relays all sensory input rather than responding selectively to emotional content. [Practice 1]

Question 3. A research team divides 120 participants into two groups: one completes a verbal reasoning task, the other a spatial rotation task. Brain imaging shows greater left-hemisphere activation for verbal tasks and greater right-hemisphere activation for spatial tasks. The researchers conclude that language is exclusively controlled by the left hemisphere. Which of the following is the most accurate critique of this conclusion?

• A) The tasks should have been administered simultaneously rather than separately.
• B) The study used too few participants to detect hemispheric differences.
• C) The study should have measured cortisol levels as an indicator of cognitive effort.
• D) Greater left-hemisphere activation supports relative specialization for language, but it does not justify concluding that the right hemisphere has no role in language processing. ✓

Explanation: The core flaw is the leap from relative specialization to exclusive control. Greater left-hemisphere activation means language tasks draw more heavily on the left hemisphere, not that the right hemisphere is uninvolved. Research on split-brain patients and left-hemisphere damage confirms the right hemisphere contributes to language functions such as prosody and pragmatics. (B) is a legitimate methodological concern in many studies, but it does not address this particular logical error, the problem is not sample size but the overreach of the conclusion itself. (A) and (C) are simply wrong: simultaneous task administration would confound results, and cortisol has nothing to do with lateralization research. [Practice 2]

Question 4. Following a stroke affecting his left frontal lobe, a patient can understand everything said to him but can no longer produce fluent spoken language. This pattern most directly implicates which brain area?

• A) Wernicke's area, located in the left temporal lobe
• B) Broca's area, located in the left frontal lobe ✓
• C) The primary motor cortex, which controls voluntary body movements
• D) The angular gyrus, which integrates visual and auditory language information

Explanation: The patient's profile, intact comprehension but severely impaired speech production, is the hallmark presentation of Broca's aphasia, caused by damage to Broca's area in the left frontal lobe. Preserved comprehension directly rules out Wernicke's area. (A) is the most common student error here: Wernicke's area damage disrupts comprehension, not production, the two areas are frequently confused. (C) is accurate about motor cortex function, but Broca's area dysfunction is specifically linguistic rather than a general movement problem, making this choice wrong at the level of analysis the question requires. [Practice 1]

Question 5. A graduate student finds that across 40 participants, those who score higher on a stress questionnaire show greater hippocampal volume loss. The correlation between stress scores and hippocampal volume is r = −0.61. What is the most appropriate conclusion from these data?

• A) Higher self-reported stress is associated with reduced hippocampal volume, but causality cannot be determined from this study. ✓
• B) Chronic stress directly causes hippocampal cell death in humans.
• C) Hippocampal volume loss causes individuals to experience higher levels of stress.
• D) The r = −0.61 indicates that stress and hippocampal volume are unrelated.

Explanation: A correlation of r = −0.61 indicates a moderately strong negative relationship: higher stress scores tend to accompany smaller hippocampal volume. Because this is an observational study, the direction of causality is unknown, stress could reduce hippocampal volume, reduced hippocampal volume could impair stress regulation, or a third variable could account for both. (B) asserts direct causation that the data do not support. (C) reverses the causal direction without justification; this is a common error when students see a correlation and assume the arrow points the more intuitive way. (D) is simply factually wrong: r = −0.61 is a meaningful negative correlation, not an absence of relationship. [Practice 3]