“…All 29 studies used video recording to capture eye gaze during conversation, however nine did not specify how many cameras were used (Beattie, 1978 , 1979 ; Rutter et al, 1978 ; Goodwin, 1980 ; Harrigan, 1985 ; Egbert, 1996 ; Lerner, 2003 ; Park, 2015 ; Blythe et al, 2018 ). Seven studies used one camera for each participant (Lamb, 1981 ; Bavelas et al, 2002 ; Eberhard and Nicholson, 2010 ; Cummins, 2012 ; Ho et al, 2015 ; Holler and Kendrick, 2015 ; Ijuin et al, 2018 ), three studies used one camera for the whole group interaction (Kendon, 1967 ; Harrigan and Steffen, 1983 ; Streeck, 2014 ), seven studies video recorded both each participant plus the whole group interaction (Kalma, 1992 ; Novick et al, 1996 ; Brône et al, 2017 ; Kendrick and Holler, 2017 ; Auer, 2018 ; Weiss, 2018 ; Zima et al, 2019 ), two studies only video recorded two out of three participants and eye tracked the third participant (Jokinen et al, 2009 , 2013 ), one study used two cameras to capture interactions in Italian language and only one camera to capture interactions in Tzeltal and Yeli Dnye languages Rossano et al ( 2009 ). Eleven studies used camera-based eye tracking technology ( Table 4 ), which permits investigators to measure participant's visual behavior by detecting and tracking movement of different parts of the eye (see review: Morimoto and Mimica, 2005 ).…”