Asking only one question in the conservation experiment.

Judith Samuel and Peter Bryant (1984).

Children below 8 years have problems with conservation tasks. A famous developmental psychologist Jean Piaget used conservation tasks. For example, if two equal amounts of plasticine are rolled into two equal balls, then one is flattened, children often believe that the flattened shape has a smaller quantity of plasticine than the ball shape has. Children hold this belief even though they have seen the transformation take place. This is an example of the conservation of mass; other conservation tasks exist for number, liquid quantity, length, weight and volume. Donaldson (1978, 1982) has pointed out that children take into account the social aspects of the task before replying to the experimenter's questions. Piaget's original tasks require the experimenter to ask whether, for example, the balls are the same size, not only after the transformation, but also before. Can you think why? The problem with asking the same question twice is that the child may think that the experimenter wants the child to change his answer. The child takes into account the social aspects of the task! Rose and Blank (1974) demonstrated this by only asking the post-transformational question to six year olds taking part in a number conservation task. More children were able to conserve, compared with those undertaking the traditional two-question task. The present study wishes to extend Rose and Blank's experiment to cover children aged between 5 and 8. They also wish to study the mass and volume tasks as well.



252 boys and girls from near Crediton, Devon. 4 age groups. Mean ages 5:3, 6:3, 7:3 and 8:3 (years:months). Each group subdivided into 3 matched on age. How many in each sub-group?

Design and Procedure.

3 subgroups.
  1. Traditional 2-question conservation task.
  2. Post-transformational question only, after seeing the two balls and the subsequent squashing of one.
  3. Fixed array. This last group did not see, for example, the two equal balls and the squashing process; instead they only saw one ball and a flattened shape.

The mass task used two playdoh cylinders. In one test the cylinders were equal. In the other test they were unequal. One squashed into a flat pancake shape or a sausage shape.

The number task used two rows of counters. Both rows were of equal length. In one test there were 6 counters in each row. In the other test, one row had 5 counters. In both tests the transformation involved either extending of bunching one of the rows.

The volume task used two identical glasses with either the same of different amounts of water. One amount was poured into either a narrower glass or a wider glass.

Each child given 4 trials with each task. 2 equal and 2 unequal. Order of trials varied between children. Why?


Mean errors taken as measurement. Equal and unequal trials pooled. One judgement task easier than standard tasks, with the fixed-array being hardest. Where the opposite result is found for any related pair of results, this is not significant. As would be expected, significant age differences also found. Significant difference between the task found; Number, then mass and then liquid volume in order of difficulty.


Samuel and Bryant view the results as supporting their view (originally Rose and Blank's view) that the second question causes the child to change their original answer, because they feel the experimenter wants a different answer. Because the fixed-array results are poorer than the one-judgement results, we can feel confident that the children carried over information from the original state of the material (e.g. 2 equal balls). This carrying over of information is the criteria for conservation having been demonstrated.


Context and Background

Ability to conserve marks the divide between pre-operational and concrete operational thought, using Piaget's theory. McGarrigle & Donaldson (1974) used 'Naughty Teddy' in an attempt to overcome the problem of the child believing he is to change his answer to the second question. It is 'Naughty Teddy' that mischievously rearranges a row of counters and in so doing, 'confuses' the experimenter. This allows the experimenter to use the second question without inferring that a change of answer is required. Light et al (1979) criticise 'Naughty Teddy' for additionally distracting the child away from attending to the transformation. Moore and Frye (1986) found that children were not detecting changes in the number of counters whilst 'Naughty Teddy' was about his business; thus supporting Light et al's criticism. Donaldson (1978) believes that Piaget did not take into account the child's social world. Language is developing in children, so often the understanding of words is heavily dependent upon the social setting in which they are uttered. Piaget's view that children cannot conserve, for example, volume until the age of 11 or 12, is challenged. It would be heresy to suggest that Piaget was wrong to assert that children's thought is 'qualitatively' different from adults, but is seems that we can disagree over the nature of this difference (i.e. 'social' rather than 'cognitive').


Porpodas (1987) felt that 'inability to conserve' could be explained in terms of the child 'forgetting'. Porpodas feels that the experimenter talking to the child in the original experiment interfered with the information stored in Short Term Memory (STM). Porpodas used 3 conditions i) traditional, ii) one questions and iii) one question with interference (i.e. performing the task whilst chatting about something else). The interference task produced the worst performance. It was concluded that the 'inability' to conserve could sometimes really be interference with STM. This theory is an additional one to Piaget's but is not an alternative to the present study's 'social context' theory.


  1. What are the IV's (2)
  2. What was the DV? (1)
  3. Name 3 conditions that belong together and place them in order of difficulty. (3)
  4. Name 3 more conditions, that belong together, and place them in order of difficulty. (3)
  5. Name Paiget's stages in which the child cannot conserve, and begins to conserve (2)

What are the methodological problems in attempting to discover how children think and feel?

Lesson 8: Cognitive Development: Piaget and Information Processing

Piaget’s Theory of Cognitive Development

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