Abstract: Objects and words can acquire a tool function in problem-solving tasks if their use meets three criteria: (1) it emphasizes stimulus properties, (2) it extends the organism skills, and (3) it mediates the solution to the problem. In order to compare the tool function of words and objects, a second-order matching to sample task was modified in such a way that a ruler could be used to stablish matching relations related to size (“similar width”, “different height”, etc.). In experiment 1, nine adults (university students) and nine 7-9 year-old-children participated. They were divided into three groups according to the order of training conditions: instrumental training using the ruler, instrumental training while receiving stimuli descriptions, or instrumental training. Results showed that neither the ruler nor the stimuli descriptions promoted correct responding. In experiment 2, a ruler was substituted by a set square. Verbal descriptions were also modified to promote relational responding (v.gr. “larger than”). Participants’ performance reached high percentages of correct responses especially when both, objects and words, were included in training. These results suggested that words and objects were equally efficient as tools. When children used them effectively, their performance resembled adult behavior. |