Experiments

• Experiments

  Laboratory Experiments:

  • Controlled environment
  • No extraneous variables, high internal validity
  • Participants aware of experiment; demand characteristics
  • Replicable
  • Lack eco validity due to artificial setting and low mundane realism

  Field Experiments:

  • Natural environment
  • Participants unaware
  • High ecological validity
  • Representative
  • Lower extraneous variable control (difficult to stop confounding variables)

  Natural Experiments:

  • IV and DV occur naturally
  • No manipulation required, e.g. Becker et al.
• Longitudinal Studies

  • Collects data from same participant group (cohort) repeatedly over extended period
  • Allows investigation of change over time, in severity or therapy effectiveness
  • Often last weeks or months, some last years or decades
  • Recruit cohort and take immediate data; baseline
  • Several test points over period, collect same data
  • Strengths
  • No individual differences impacting results; same patients
  • Large courts,mostly high representative
  • Weaknesses
  • High drop-off rate, may be intrusive; due to amount of data collection points
  • Early data may become outdated or irrelevant
• Cross-Sectional Studies

  • Cross-section of participants studied at once
  • “Snapshot” of current day
  • Assumption younger group turn into older group in time
  • Strengths
  • Cheaper and time-efficient, compared to longitudinal
  • Valid, up to date data, analysed immediately reflecting current mental health issues
  • Weaknesses
  • Cannot establish causes, just current attitudes
  • Results may be time-locked and ungeneralisable to other cultures or societies
• Cross-Culture Studies

  • Data collected from samples in different cultures for comparisons
  • Clinical Psychology:
  • Find cultural impact on mental health
  • Experience and diagnosis
  • Treatment effectiveness
  • Attitudes
  • Universal prevalence: Nature
  • Different result: Nurture
  • EMIC: Behaviour 1 culture, fully know norms
  • ETIC: Multiple cultures outside, compare
  • Strength
  • Eliminate ethnocentrism, increase generalisability
  • Demonstrate nature and nurture roles
  • Weakness
  • Same procedure may not suit all, invalid (cultural stigma)
  • Subjective interpretation of other cultures due to researcher norms
• Blind?

  • Double-blind experiment:
  • Participants and researcher unaware of study aim/hypothesis
  • Controls for demand characteristics and experimenter effects
  • Enables objective, bias-free behavior interpretation
  • Single-blind experiment:
  • Participants unaware of studies true aim (deception) or that they are even in a study
  • Reduces demand characteristics