Table 2 Operationalised definitions of behaviours coded as control variables; and participant and examiner behaviours used in the analysis

  Participant verbalisation (duration)

The participant’s speech; These may be utterances (e.g. ‘erm’), words, phrases or sentences. The person may use speech for the purpose of communication with someone else, e.g. asking a question, making a comment, answering a question or the speech may be used when the person is talking to himself or herself. The participant’s speech may be intelligible or unintelligible.

  Participant question (event)

The participant asks the examiner a question. For example, ‘Did you drive here?’

  Participant offers information (event)

The participant spontaneously (not in response to a question) offers information. The information may or may not be about them. For example, ‘I went to the beach on holiday’ or ‘the cartoon is funny’.

  Participant verbal response (event)

The participant responds verbally to a question, statement, comment, prompt or request made by the examiner by providing information. N.b. this code also includes the participant’s description of the cartoons in the Cartoon condition.

  Participant positive facial expression (duration)

The participant demonstrates a positive facial expression, for example, laughing or smiling. Facial expression must clearly indicate expression of pleasure in activity or conversation. Facial expression may or may not be directed towards the examiner.

  Participant looks at examiner (duration)

The participant looks in the direction of the examiner’s eyes or face.

  Participant nod/shake (event)

The participant responds to a question, statement, comment or prompt made by the examiner, by nodding their head to indicate ‘yes’ or shaking their head to indicate ‘no’. This does not include use of Makaton or British Sign Language.

  Participant descriptive gestures (duration)

The participant uses movements of their arms or hands to help them describe something.

  Participant fidget (duration)

The participant displays restless, repetitive, non-rhythmic, non-functional motor movements, such as, moving their hands, touching their face or hair or moving an object, or wriggling in their seat. This code does not include stereotyped behaviours, which are rhythmic, unusual seemingly purposeless movements of their body or objects (based on Lesniak-Karpiak, Mazzocco & Ross, 2003 [23]).

  Examiner verbalisation (duration)

The examiner’s speech; These may be utterances (e.g. ‘erm’), words, phrases or sentences. The person may use speech for the purpose of communication with someone else, e.g. asking a question, making a comment, answering a question or the speech may be used when the person is talking to himself or herself. The examiner’s speech may be intelligible or unintelligible.

  Examiner question (event)

The examiner asks the participant a question, which requires a response from the participant. For example’ What books do you like?’

  Examiner prompt (event)

The examiner prompts the participant to respond by repeating or slightly paraphrasing the original question, request, comment or piece of information.

  Examiner verbal response (event)

The examiner responds to the participant’s verbal question, comment, statement or offering of information using verbal communication to give the appropriate information.

  Examiner Offers information (event)

The examiner spontaneously (not in response to a question) offers information. The information may or may not be about themselves. For example ‘I came from Birmingham’. N.b. this code also includes the examiner’s description of the cartoons in the Cartoon condition.

  Participant engage with task (duration)

The participant looks at and/or touches an object allocated for a condition. This may be reading a magazine / newspaper, colouring with felt tips, listening to the radio in the ‘Break’ condition; looking at or touching the photographs in the ‘Photograph’ condition; looking at or touching the cartoon in the ‘Cartoon’ condition. Objects that have not been incorporated as part of the social presses should not be coded, e.g. if the person is drinking from a cup or mug, which is on the table. This code does not apply to the ‘Conversation’ condition because no objects are required for this condition.

  Examiner looks at participant (duration)

The examiner is looking in the direction of the participant’s eyes or face.