Evaluation of Method/Procedure: Strengths: A strength of Sperry’s procedure was that by using a mixture of quasi-experiments and clinical case studies, he was able to combine qualitative and quantitative approaches. The quasi-experiment is a quantitative method of data collection, that is, it provides information in the form of numbers and frequencies, and so can be easily analysed statistically. The information that is gathered is regarded as fairly reliable but not very valid. On the other hand, the case study is a qualitative method of data collection which is concerned with describing meaning. It is argued that what the case study loses on reliability it gains in terms of validity. Thus, such a combination of methods allows for the collection of statistically reliable information to be enhanced by information about the research participants’ explanations. Weaknesses: A major criticism of the procedure was Sperry’s sample. 11 participants is a very small sample, however Sperry may not have had any control over this - there may not be very many split-brain patients available to study. The small sample also enabled Sperry to gain more in-depth data. The 11 split-brain patients were lumped together as the experimental group, but some of the patients had experienced more deconnection than others. We also cannot be sure how long each of the participants had experienced ineffective drug therapy which could have been affecting the findings. The comparison group used by Sperry, was people with no inter-hemisphere deconnection, it could be argued that a much more valid group would be epileptic people who had not had their hemispheres deconnected. A further weakness of the study relates to ecological validity. The findings of the study would be unlikely to be found in a real life situation because a person with severed corpus callosum who had both eyes would be able to compensate for such a loss.