perry et al

• background

  • Investigated the effect of oxytocin on preferred interpersonal distances, focusing on individuals with different levels of empathy.
  • Amygdala function: Plays a key role in regulating personal space, influenced by oxytocin.
  • People uncomfortable with close proximity show higher amygdala activity.
  • Interaction Effect Hypothesis: Perry tested whether oxytocin and empathy interact to influence personal space preferences.
• psychology being investigated

  • Oxytocin: A hormone linked to social bonding, trust, and empathy.
  • Empathy: Ability to understand and share emotions of others.
  • Social Salience Hypothesis: Suggests oxytocin enhances attention to social cues (e.g., body language), modifying behavior based on social context.
  • Interpersonal distance (personal space): Preferred physical space between individuals, depending on relationship closeness
• aims

  • Investigate how oxytocin affects preferred personal space, depending on empathy levels.
  • Test whether oxytocin's effects on social behavior differ between high- and low-empathy individuals.
• research method and design

  • Research Method: Lab Experiment (University of Haifa, Israel).
  • Self-Report Method: Interpersonal Reactivity Index (IRI) questionnaire to measure empathy.
  • Sampling Method: Volunteer Sampling (undergraduate students).
• sample

  • 54 male undergraduates (University of Haifa, Israel).
  • Age range: 19 - 32 years (Mean = 25 years).
  • 5 were left-handed, all had normal or corrected vision, no psychiatric/neurological disorders.
  • Received course credit or payment for participation.
• independent variables

  1️⃣ Empathy Levels:

  2️⃣ Treatment Conditions

  • Oxytocin (24 IU nasal spray).
  • Placebo (saline solution).

  3️⃣ Protagonist Type (Experiment 1):

  4️⃣ Experimental vs. Control Conditions (Experiment 2):

  • Experimental: Chair distance in a room preference task.
  • Control: Distance between a table and plant (non-social condition).
• dependent variables

  1️⃣ Experiment 1: Preferred Interpersonal Distance (CID Paradigm).

  2️⃣ Experiment 2: Mean preferred distance and angle between chairs in a room setup.
• general procedure

  1️⃣ Visit 1 & Visit 2: Participants came twice, one week apart (received oxytocin in one session, placebo in the other).

  2️⃣ Empathy Test: Completed IRI questionnaire.

  3️⃣ Oxytocin or Placebo Administration: Self-administered nasal spray (24 IU) under supervision.

  4️⃣ Waiting Period: 45 minutes of reading magazines (minimized social interaction).

  5️⃣ Experimental Tasks: Participants completed Experiment 1 or 2, depending on order assigned.
• experiment 1: comfortable interpersonal paradigm

  1️⃣ Participants saw a virtual 3D room on a computer screen.

  2️⃣ Figures (friend, stranger, authority, or ball) approached from 8 directions.

  3️⃣ Task: Press a button to stop the figure when they felt uncomfortable.

  4️⃣ Each figure appeared 3 times from each direction (24 trials per figure).

  5️⃣ Total: 96 trials per participant.

  6️⃣ Distance was recorded as a percentage of remaining space (0% = closest, 100% = farthest).
• experiment 2: choosing room setups

  1️⃣ Participants viewed pairs of room setups on a computer.

  2️⃣ Chairs varied in distance (20 cm - 140 cm) & angle (0°, 45°, 90°).

  3️⃣ Control Condition: Distance between a table and plant (non-social).

  4️⃣ 168 total trials (84 pairs x 2 repetitions).
• results 1

  • Preferred distances (mean % remaining space):
  • Friend: 12.4%
  • Authority: 34.1%
  • Stranger: 39.8%
  • Ball: 20.2%
  • Oxytocin + High Empathy: Preferred closer distances (23.2%).
  • Oxytocin + Low Empathy: Preferred greater distances (30.2%).
• results 2

  • High Empathy + Oxytocin → Chose closer chair distances (78 cm).
  • Low Empathy + Oxytocin → Chose larger chair distances (80 cm).
  • Oxytocin had no effect in non-social (table-plant) condition.
• conclusions

  ✔ Oxytocin enhances social cue processing, but effects depend on empathy levels.

  ✔ High-empathy individuals → Oxytocin reduces preferred distance.

  ✔ Low-empathy individuals → Oxytocin increases preferred distance.

  ✔ People need less personal space with friends than with strangers.
• controls

  Double-Blind Design → Neither participants nor researchers knew who received oxytocin/placebo (reduces bias).

  Standardized Oxytocin Administration → 3 drops per nostril, supervised.

  Counterbalancing → Half did Experiment 1 first, the other half did Experiment 2 first (reduces order effects).

  45-minute waiting period after oxytocin administration → Allowed full effect before testing.

  Empathy groups were pre-determined using IRI questionnaire.