2.4.1. Pretest

To assess the initial level for deictic relations in order to ensure all groups were at the same level, the participants completed a pretest measuring of perspective-taking abilities. The perspective-taking protocol contained a subset of the 18 trials (six per complexity level) used in the Barnes-Holmes protocol. Other studies [10, 14, 21] also used this short version of 18 trials for testing. This pretest protocol contained a random presentation of all three deictic relational frames across all three complexity levels. Each trial consisted of two questions (e.g., "Where am I sitting?/Where are you sitting?"). The actual questions depended on the type of relation being tested. After answering the first question, participants were asked the second question immediately. A correct response to a trial required that the participants answered both questions correctly. No visual aids and no feedback were provided for subjects' responses. The way of proceeding was as follows: the experimenter read all tasks aloud from the perspectivetaking protocol, participants responded orally and the experimenter recorded each response. The researcher repeated a question twice, if requested to do so by a participant.

After the pretest sessions, participants were assigned to each of three conditions (five subjects in each condition) ensuring that groups were at the same level for deictic relation responding before the experimental condition was implemented. Although in all conditions the way to proceed was the same as for the pretest, the order of the presentation of the trials was randomized in a different sequence to the pretest protocol. This new sequence was the same for all conditions. If the participant requested, the researcher repeated a question a maximum of two times. Any form of corrective feedback was provided for participants' responses.
