## Disciplines That Diagnose or Illuminate Human Behavior  


1. Clinical Psychology  
   • Core Purpose: Formal diagnosis and evidence-based treatment of mental-health disorders and maladaptive behaviors.  
   • Typical Tools: Structured interviews, DSM-5/ICD-11 criteria, validated psychometric tests (e.g., MMPI-3), randomized controlled therapy trials.  
   • Context Snapshot: A clinician evaluating persistent social withdrawal in an adolescent will use parent/teacher reports, standardized rating scales, and direct observation to determine if the pattern meets criteria for Social Anxiety Disorder or Autism Spectrum Disorder, then recommend CBT or family therapy accordingly.

2. Behavioral Psychology / Behaviorism  
   • Core Purpose: Explain how all behaviors (normal or problematic) are learned and can be modified through conditioning principles.  
   • Typical Tools: Operant conditioning protocols, token economies, single-case experimental designs.  
   • Context Snapshot: A school team reduces classroom tantrums by reinforcing on-task behavior with immediate praise and small rewards, documenting frequency before, during, and after intervention to confirm effectiveness.

3. Cognitive Psychology  
   • Core Purpose: Uncover the mental mechanisms—attention, memory, decision-making—that drive outward behavior.  
   • Typical Tools: Laboratory reaction-time tasks, eye-tracking, fMRI, computational modeling.  
   • Context Snapshot: Researchers discover that split-second “implicit bias” on an IAT predicts real-world hiring decisions, prompting HR departments to adopt structured interviews to offset unconscious preferences.

4. Neuropsychology  
   • Core Purpose: Link specific brain structures/functions to behavioral changes, especially after injury, illness, or neurodevelopmental conditions.  
   • Typical Tools: Neuroimaging (MRI, DTI), lesion mapping, domain-specific cognitive batteries (e.g., Wisconsin Card Sorting Test).  
   • Context Snapshot: Following a mild traumatic brain injury, a patient’s sudden irritability and poor impulse control are traced via neuroimaging to damage in the right orbitofrontal cortex; targeted cognitive rehabilitation is then prescribed.

5. Applied Behavior Analysis (ABA)  
   • Core Purpose: Systematically apply behavioral principles to change socially significant behaviors in real-world settings.  
   • Typical Tools: Functional behavior assessment (FBA), discrete-trial training, data-driven progress graphs.  
   • Context Snapshot: A child with autism who engages in self-injury receives an FBA revealing that head-hitting functions to escape noisy environments; intervention teaches an alternative communication response (“break, please”) while gradually increasing noise tolerance.

6. Social Psychology  
   • Core Purpose: Understand how social context—groups, norms, relationships—shapes individual and collective behavior.  
   • Typical Tools: Controlled experiments, large-scale surveys, archival data analysis.  
   • Context Snapshot: An experiment shows that merely reminding people of their recycling identity increases actual recycling rates by 25 %, informing municipal “nudge” campaigns.

7. Behavioral Economics  
   • Core Purpose: Merge psychological insights with economic models to explain why people systematically deviate from “rational” choices.  
   • Typical Tools: Choice-architecture field experiments, incentive-compatible games, econometric modeling.  
   • Context Snapshot: A pension program switches from opt-in to opt-out enrollment; participation rises from 45 % to 92 %, demonstrating the power of default bias and guiding national retirement-policy reform.

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Quick Comparison at a Glance
• Diagnosis-focused: Clinical Psychology, Neuropsychology  
• Mechanism-focused: Cognitive Psychology, Behavioral Psychology  
• Context-focused: Social Psychology, Behavioral Economics  
• Intervention-focused: Applied Behavior Analysis  
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