Study title

United Kingdom, Spain

Individual

1. fMRI Stag HuntWe investigated the idea of bias in social decision making by conducting a functional MRI study utilising a version of the Stag Hunt (SH) task. All stimuli were projected to participants via goggles in the MRI scanner and presented using Presentation software. Participants completed a version of the Stag Hunt task while in the MR scanner. They were informed of their “opponent’s” nationality (which was actually a computer programme) by presentation of a national flag – either the Saltire, St George’s Cross, Union Jack, or EU – which remained present throughout. After an intial round with no flag present, each participant completed the task four times, once each with an opponent from each nationality, the order of which was counterbalanced across participants. 31 healthy adult volunteers (aged 18-45) were recruited from the general population. As the UK is a multi-national state, in which a resident of Scotland might identify as primarily Scottish or as British (or indeed as both) participants were pre-screened using the following question: ‘If you were forced to choose only one, you would identify yourself as: [Scottish/British/European/Other/English/Welsh/Northern Irish].’ Only those who self-identified primarily as Scottish were included in the study. Participants were not aware that this response was required for study inclusion, and relevant questions were embedded within a multi-focussed pre-screening questionnaire designed to ascertain the suitability of participants for MR scanning. Participants were free from mental illness, neurological disorders and previous brain injury, were right handed and were suitable for MRI scanning (for example, no metal implants or prostheses or claustrophobia). Suitability was confirmed by the MRI pre-screening form and by interview. Participants were paid £20 compensation for their participation in this experiment. All participants provided written informed consent and were made aware that they may withdraw from the study at any time, and be at no disadvantage if they chose to do so.2. fMRI pain-empathyDuring an fMRI sequence, participants viewed a series of videos of individuals experiencing shoulder pain. All stimuli were projected to participants via goggles in the MRI scanner and presented using Presentation software. Following each video, participants were asked to rate the level of the pain being expressed on a scale ranging from 0 (no pain) to 100 (most pain imaginable). A total of 64 videos were shown to each participant, half of which showed individuals represented explicitly as ‘Scottish’ (same nationality) and half of which showed individuals represented explicitly as ‘English’ (different nationality). The explicit nationality cue was indicated as either “Scottish” or “English” appearing on screen before each video. In addition, half of the videos were preceded by an implicit prime of the Scottish national flag (Saltire), which was backward masked to ensure presentation below the threshold of conscious awareness, while the other half were preceded by a scrambled version of the flag. A scrambled version of the Scottish flag was created was created by randomising the blue and white colour of the Scottish flag using Presentation software (Neurobehavioural Systems, https://www.neurobs.com). The implicit prime was presented before half of the videos, counterbalanced across nationalities. Stimulus videos previously classified as either “high pain” or “low pain” using the facial action coding system (Ekman & Friesen 1978) were also counterbalanced across conditions. To explore the impact of the implicit Scottish flag and the explicit nationality ‘Scottish’ or ‘English’ of the person in pain on participants’ behavioural and neural responses to viewing others in pain, we employed a 2 (Scottish flag prime v scrambled flag prime) X 2 (‘Scottish’ nationality v ‘English’ nationality) within subjects experiment design with high and low pain videos collapsed across all conditions.Thirty three healthy participants took part in this fMRI study. All participants in the study were healthy individuals recruited from community volunteers and were aged between 18 and 45 (15 females and 12 males). Participants were free from mental illness, neurological disorders and previous brain injury, were right handed and were suitable for MRI scanning (for example, no metal implants or prostheses or claustrophobia). Suitability was confirmed by the MRI pre-screening form and by interview. Participants were paid £20 compensation for their participation in this experiment. As the UK is a multi-national state, in which a resident of Scotland might identify as primarily Scottish or as British (or indeed as both) participants were pre-screened using the following question: ‘If you were forced to choose only one, you would identify yourself as: [Scottish/British/European/Other/English/Welsh/Northern Irish].’ Only those who self-identified primarily as Scottish were included in the study. Participants were not aware that this response was required for study inclusion, and relevant questions were embedded within a multi-focussed questionnaire designed to ascertain the suitability of participants for MR scanning. All participants provided written informed consent and were made aware that they may withdraw from the study at any time, and be at no disadvantage if they chose to do so.3. Hormones and BehaviourA total of 336 healthy male participants, aged between 18 and 90 were randomly recruited from the local population in Edinburgh, Scotland, UK (N = 136; age: M = 38.54 ± 18.72 years ) and from Barcelona, Catalonia, Spain (N = 200; age: M = 22.43 ± 5.22 years). All were pre-screened to exclude a number of significant behavioural and physiological traits that could produce confounding physiological effects in the analysis of T and sAA. Participants were also pre-screened to allow groups to be created on the basis of the participants’ self-declared primary identity while avoiding drawing attention to the identity focus of the research during the experimental intervention. Amongst other questions, participants were asked 'when forced' which one, and only one, identity group they belonged to: European Union, British/Spanish, or Scottish/Catalonian. The final sample included: ‘Scottish’ (n = 74), ‘British’ (n = 58), and ‘European’ (n = 5) in the British sample and ‘Catalonian’ (n = 133), ‘Spanish’ (n = 42), and ‘European’ (n = 25) in the Spanish sample. All participants provided written informed consent and were made aware that they may withdraw from the study at any time, and be at no disadvantage if they chose to do so. Participants played the Ultimatum Game by writing their offers on a laminated game card, which the confederate then indicating whether they accepted or rejected. The confederate had a similar card, on which they wrote their offers, and on which the participants indicated their acceptance or rejection. Cards had the flag indicating identity of the player at the top. No text or other indication of purpose or identity was present.Surveys included demographic questions, self-identification of territorial identity, the Moral Foundations Questionnaire (MFQ; Graham et al., 2011), and the abbreviated Five Factor Inventory (NEO-FFI; Costa & McCrae, 1992). Four saliva samples were collected into a 3.5mL sterile polypropylene cryovials using standard salivary-hormone collection procedures (Dickerson & Kemeny 2004; Schultheiss & Stanton 2009) and via ‘passive drool’ (Navazesh, 1993). The first sample was collected to establish a ‘baseline’, after twenty minutes of participant isolation in a quiet room without any stimuli. The second sample was collected after participants had played ten iterations of the ‘ultimatum game’ against a confederate posing as another participant. The third sample was collected after participants had played another ten iterations of the Ultimatum Game against the same confederate participant. The fourth sample was collected to assess ‘recovery’, twenty minutes after completion of the game.