Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)




Piaget (1929) contends that a verbal interview is the only procedure which is flexible enough to follow and examine the development of cognitive processes in children. However verbal methods are inconsistent with the suggestion by Piaget (1951, 1963) and several colleagues (Furth, 1964, 1966; Sinclair-de-Zwart, 1969) that language merely reflects underlying cognitive processes, and is not a source of logical development. In addition verbal methods allow for verbal misunderstandings by both subjects and experimenters, provide for experimenter bias and may foster response sets.

To minimize these theoretical and methodological difficulties, several investigations (e.g., Braine, 1959, 1962; Sawda & Nelson, 1968) have employed nonverbal, manipulative techniques. None of these studies made direct comparisons of results from verbal and nonverbal methods; none entirely eliminated verbal interactions between subject and examiner.

This study presents a behavioral technique for the assessment of conservation of length based on operant work by Blough (1966) and Bijou and Baer (1966). It was designed to compare nonverbal results with results obtained in a Piagetian-type verbal interview, and to eliminate verbal interactions.

Thirty-two first grade children were evaluated individually by both verbal and nonverbal methods in counterbalanced order. First graders were selected to Insure both conservers and nonconservers In the subject population.

The verbal condition consisted of a Piagetian-type interview, although standardized questions were used so that every subject received the same interview. Four similar tasks were presented following Piaget’s (Piaget, Inhelder & Szeminska, 1960) example.

In the nonverbal conditions, subjects were trained to press one button for stimuli of the same length and another button for stimuli of different length. Following training, subjects were exposed to eight test stimuli in which stimuli of the same length were staggered so that the end points did not coincide. In each condition subjects were required to make appropriate responses on 75% of the items to be considered conservers.

It was predicted that (1) nonverbal techniques would distinguish between conservers and nonconservers; (2) that verbal and nonverbal methods would yield similar decisions concerning the conservation ability of any particular subject; and (3) to the extent that the conservation decisions differed for any subject, nonverbal method would yield more and younger conservers than verbal methods.

With the exception of the predicted age difference, all hypotheses were supported. Reasons for falling to support the age hypothesis are presented. It was concluded that nonverbal techniques can be applied to Piagetian conservation tasks, and that such techniques are valid for the assessment of conservation. Results support Piaget's conservation of length construct and clinical methodology. The advantages of nonverbal methods are discussed and applications to nonverbal populations suggested. Limitations of the present study and suggestions for future research are presented.