Table 1: Synoptic representation of the reviewed studies on communication.

Studies 2015	Participants	Range Age	AT	Targeted Behaviors	Outcomes
Copple et al. [22]	3	3.5-5	SGD	Request and Choice	Three positive
Couper et al. [23]	9	4-9	SGD	Manual Signs	Five positive
Kasari et al. [24]	61	5-8	SGD	Communicative Skills	Sixty one positive
Flores et al. [25]	5	6-10	I - Pad and Cards	Communicative Skills	Two negative
Ganz et al. [26]	2	4-5	Verbal modelling and PECS	Verbal Requests	Two negative
Yoder & Liberman [27]	36	1.5-5	PECS and Pre - linguistic milieu teaching	Coordinated Attention	Thirty six positive
Franco et al. [28]	1	7	SGD	Vocal Utterances	One positive
Ganz et al. [29]	3	6-9	PECS	Requests Words	Three positive
Son et al. [30]	3	4-5	PECS and VOCA	Requesting Behaviour	Three positive
Sigafoos et al. [31]	2	12-16	SGD	Requests Behaviour	One negative
Sigafoos et al. [32]	1	12	SGD	Request Objects	One positive