Perry et al. (2015)

AIM

to investigate the effect of oxytocin on preferred interpersonal distance for those scoring high or low in empathy traits

In the background to their study, Perry et al. outlined how biological factors affect interpersonal distance (personal space) preferences.

Outline how biological factors affect interpersonal distance (personal space) preferences

• oxytocin plays a role in personal space/empathy/social bonding/social salience

• lesions in amygdala appear to reduce the need for personal space

• amygdala activity in healthy individuals is correlated with feeling uncomfortable at close distances

• amygdala activity is affected by levels of oxytocin

Describe the procedure of one trial for experiment 1 from the fixation point appeared unitl the end of the trial (9990/11_Winter_2025)

• the ps was shown a still picture

• this was of a circular room

PRODCEDURE: OT ADMINISTRATION

• 24 international unit of 250ml of intranasal OT

• a placebo saline solution

• the nasal drops were self-administered by ps using a nasal dropper, under supervision of the experimenter.

• double-blind technique: neither the ps nor the experimenter knew whether the ps has received the OT or saline solution.

PROCEDURE: ASSESSMENT OF EMPATHY

• complete the IRI online questionaires

• then, ps were given nature magazines and wiated in a quiet room for 45mins

• the order of experiments was counterbalanced: half the ps were undertook OT one week then saline the next week, the other do the reversed order.

PROCEDURE: EXPERIMENT 1: THE COMFORTABLE INTERPERSONAL DISTANCE (CID) PARADIGM

• repeated measures design - all ps provided their preferences across all conditions

• a circle was presented on a computer screen and ps were instructed to imagine themselves in the centre of the room with another person approaching them along the radius

• the ps pressed the keyboard space bar to indicate where they want the person to stop approaching

• the comp animation had options for the imagined other to be: a close friend, stranger, authority figure or a rolling ball. ( 4 conditions - 3rd independent variable.

• the animation stopped when the figures collided or ps pressed the space bar.

• there were 24 trials for each figure and 96 trials in total. (4×24=96 trials)

EXPERIMENT 1: CID PARADIGM

the CID paradigm, a computer animation, was used to measure preferred interpersonal distance. this process involved:

• displaying the word (the protagonists) “friend”, “stranger”, “authority” or “ball” on the screen for 1s

• the ps must gaze at a fixation point which appears on the screen for 0.5s

• the next screen then shows a plan of a circular room with a stick person at the center representing the ps

• next comes an animation that lasts up to 3s: from one of the eight entrance, the protagonists appear and approach the participants

• the ps has to press the space bar when they want the protagonists to stop moving.

• 96 trials with 4 protagonists → 3 times from each of the eight doors

• Interpersonal distance was calculated as the percentage of distance remaining between the protagonist and the central figure, from 0% to 100% → a low score represented close proximity and a high score represented farther proximity.

EXPERIMENT 1; IV

1. Empathy (between-subjects)

• level 1: high ( >=40)

• level 2: low (<=33)

2. Treatment (within subjects)

• Level 1: Oxytocin (24 IU transnasal administration)

• Level 2: Placebo (sterile saline solution, intranasally administered)

3. Social condition

• stranger

• authority figure (boss or teacher)

• friend

• rolling ball

EXPERIMENT 1: DV

• Interpersonal distance preferences

• key measurement: the percentage of remaining distnace between the ps (represented at the center of the room ) and stopped protagonists.

→ higher the percentage, the greater the ps’s preferred distance from the approaching approaching figure, reflecting a greater need for personal space in that interaction

PROCEDURE: EXPERIMENT 2: CHOOSING ROOMS

• involved a computer-based task called “choosing rooms”, which measured 2 dependent variables:

+ the mean average preferred distance between furniture items

+ the average preferred angle between furniture items

• the ps were instructed to design a room layout for a personal conversation with another participant

• they were shown colour pictures of two every similar rooms for each trial for them to choose the one they prefer.

• They were told that this information would be used to design a room according to their preference

• The computerised stimuli were coloured pictures with 2 identical chairs in the middle, a table on one side, a cupboard, a plant, a lamp, and a clock.

• The experimental condition was preferred distance between chairs and consisted of the following stimuli:

+ distance between the chairs (20-140cm with intervals of 20cm)

+ angle of the chairs position (0 degree: both facing forwards, 45 degrees each or 90 degrees: facing each other)

• the control condition was preferred distance between table and plant and consisted of:

+ distance bw the table and the plant (200-320cm with interval of 20cm)

+ angle of the table and plant position (0 degree: both facing forwards, 45 degrees each or 90 degrees: facing each other)

• the experiment includes 21 diff pairs of chair distances, 21 diff pairs of table-plant differences, and 3 options of each pair of angles, repeated 7 times → 21 pairs. Each ps was shown a total of 84 pairs, each repeated twice to equal 168 pairs overall.

• The 2 pictures were shown on the screen for 2s and the ps had to select their preference. the mean preferred distance between chairs, between table and plant and the preferred angle for these furniture was calculated.

EXPERIMENT 2: SHORTER SUM

• PS were given either oxytocin or a placebo nasal spray

• they were shown pairs of virtual rooms on a computer screen positioned 60cm away

• each room contained 2 identical chairs in the center, a table on the side, a plant on the other, along with a closet, lamp, and clock

• the rooms differed in the distance between chairs, table and plant positions, or chair angles.

• Ps chose which room they prefered for an imagined future conversation about personal topics (at the end of 2 weeks of experimental trials). → deception, no such conversation was actually took place.

• Each pair of room images was displayed for 2s, followed a prompt asking ps to indicate their preferred room (left or right)

• the experiment included 21 diff chair distances pairings, 21 table-plant distance pairings, and 21 angle pairings. Each pairing was presented twice → a total of 168 trials for each ps

• ps completed the task twice (oxytocin and placebo conditions) once week apart.

EXPERIMENT 2: IV

1. Empathy(between-subjects)

• level 1: high >=40

• level 2: low <=33

2. Treatment (within-subject)

• level 1: oxytocin (24 international unit of intranasal OT)

• level 2: placebo (sterile saline solution, intranasally administered)

3. preferred choice of picture, chair distance to plant:

both the distance between chairs or table-plant was systematically varied

• chair condition (experimental): represented the interpersonal distance variable measured as the distance between two chairs in the virtuals rooms

• table conditions (control): distance bw table and plant served as a control for non-social distance preferences. any significant diff in preferred chair distances under oxytocin could then be more confidently attributed to its effects on interpersonal space, rather than general preference for larger space.

more detail on the control

(This control condition, from Perry et al.'s study on oxytocin and empathy, distinguishes between social and non-social spatial preferences. By comparing "chair-to-chair" (social) distances with "table-to-plant" (non-social) distances, researchers proved that oxytocin's effects were specific to interpersonal space, not just a general desire for more space.

Key Details on the Tables Condition (Control):

The Concept: Participants were shown virtual rooms with furniture. The Table-Plant pairing represented a neutral, inanimate, non-social relationship.

Purpose of Control: If oxytocin caused people to move chairs closer together (social) but did not affect how they positioned tables to plants (non-social), researchers could confidently conclude that oxytocin increases social closeness specifically.)

EXPERIMENT 2: DV

2 primary DV:

• MEAN PREFERRED DISTANCE BETWEEN CHAIRS (IN CM) → this measures directly assessed the ps’s comfort levels with physical proximity to another person. further chair → greater preference for interpersonal space. closer chair → greater preference for interpersonal space.

• MEAN PREFERRED ANGLE BETWEEN CHAIRS (IN DEGREES) → could subtly influence the dynamics of social interaction, allowed to explore whether oxytocin or empathy might influence not just the preferred distance, nut also the orientation for an intimate conversation.