Final answer:
Dr. Kaal is studying stress from a biological perspective, using brain-scanning techniques to examine the physiological responses to stress, in accordance with biological psychology or neuroscience principles.
Step-by-step explanation:
Dr. Kaal's research approach, which involves utilizing brain-scanning techniques to study the effects of stress on the brain, aligns with the biological perspective in psychology. This perspective emphasizes the physiological and neurological bases of behavior and mental processes. Dr. Kaal's interest in the brain's response to stressors focuses on the biological correlates of psychological stress, which falls squarely within the realm of biological psychology or neuroscience.
By assessing changes in brain activity before and after stressful situations, Dr. Kaal is investigating the physiological responses that occur as a result of stress, in line with the response-based definitions of stress highlighted by researchers like Hans Selye.