“…The means by which teaching signals can be communicated to a learning agent vary. They can be provided via natural language (Kuhlmann et al, 2004 ; Cruz et al, 2015 ; Paléologue et al, 2018 ), computer vision (Atkeson and Schaal, 1997 ; Najar et al, 2020b ), hand-written programs (Maclin and Shavlik, 1996 ; Maclin et al, 2005a , b ; Torrey et al, 2008 ), artificial interfaces (Abbeel et al, 2010 ; Suay and Chernova, 2011 ; Knox et al, 2013 ), or physical interaction (Lozano-Perez, 1983 ; Akgun et al, 2012 ). Despite the variety of communication channels, we can distinguish two main categories of teaching signals based on how they are produced: advice and demonstration.…”