PSYC 1100 Week 7 Discussion

PSYC 1100 Week 7 Discussion | Kwantlen Polytechnic University

Peer Learning Discussion Week 7

Bryant and McConkey (1989) presented an interesting case study of an individual called DB, who was diagnosed as having a “visual conversion disorder”— that is, DB had a loss in visual functioning that could not be explained by a physical disorder, was not under voluntary control, and was apparently influenced by psychological factors. Despite this diagnosis, Bryant and McConkey found that DB performed a particular problem-solving task better when visual cues were present than when they were not. Below is the summary of this case. Read the case and discuss the following questions:

1. How do you account for DB’s apparent blindness in his right eye?

2. What were the independent and dependent variables in this single-participant experiment?

3. What are the limitations to the experiment?

Case Summary:

Bryant and McConkey (1989) presented an interesting case study of DB, who was diagnosed as having a “visual conversion disorder”—that is, he had a loss in visual functioning that could not be explained by a physical disorder, was not under voluntary control, and was apparently influenced by psychological factors. 

DB was a 33-year-old, single, white male, employed in a clerical job, living with his parents, and a regular outpatient at a major Veterans Affairs hospital in Sydney, Australia. His visual disorder began when he was hit in the right eye with a rifle butt during military training, leading to a three-week hospitalization. During this period, he reported pain and impaired vision in his right eye. After receiving ophthalmologic assessment and treatment as an outpatient for three months following discharge, DB reported that he could not see anything with his right eye, and that whatever he did see, he forgot. He then received intensive opthalmological, neurological, and neuropsychological assessments, which revealed no apparent physical basis for his visual disorder. 

For the purposes of their study, Bryant and McConkey informed DB that they were administering a task that would assist in understanding his visual disorder. They did not tell him that the task itself included a visual component. They tested DB on twenty-one sessions over a period of five months. With his left eye covered, he was told that his task was to turn off a tone on a machine in front of him by pressing one of three switches. In the experimental condition, visual cues were present; in the control sessions they were not.

At the beginning of sessions 15-19, the researchers gave motivation instructions, informing DB that he was not performing as well as could be expected and that unless his performance improved, his participation in the study would end. Among the major findings of this experimental case study were: a) DB made more correct responses when the visual cues were present than when they were absent; b) DB made more correct responses when the motivation instructions were given than when they were not; and c) DB responded more slowly when the motivation instructions were given than when they were not. These findings indicated that the performance of DB on the decision task was influenced by both the visual and the motivational information. The authors concluded that their findings are consistent with the notion that the motivational factors associated with DB’s visual disorder were flexible enough to allow him to perform in a way that indicated virtually no disorder of visual functioning while at the same time reporting that he had such a disorder. 

Also of interest is the finding that DB responded more slowly when visual information was present than when it was not—perhaps because the processing of the visual information forced a choice of whether or not to press the correct switch. He also responded more slowly when he was given motivation instructions than when he was not—perhaps because the motivating instructions created a conflict in him: He wanted to continue to participate in the study by giving a correct performance, but it conflicted with his need to be assured of his blindness.