Chapter 6 Getting Things Under Control

Chapter 6: Getting Things Under Control John Snow: in 1850s, there was a cholera outbreak in London, and the leading theory of the day was effluvia theory, which meant that cholera was spread by coughing and inhaling the fumes of diseased people. Snow, in contrast, thought that cholera was due to contamination of the water supply (with the feces of infected victims). He set out to test his theory. In London at the time, there were many different sources of water supply, each serving different districts, so the incidence of cholera could be matched with different water supplies, which varied in degree of contamination. There was a problem here, though, which Snow realized. It had to do with selection bias—socioeconomic status differed according to district. Fortunately for Snow, in London, there happened to be two water companies that supplied water unsystematically (randomly) to a single neighborhood. There were even cases in which a single house had water from a company different from the one supplying the houses on either side of it. Thus, SES was held constant (or as close as it could get in a naturally occurring situation). Such a circumstance would not have been of any benefit if the water supplies had been equally contaminated. Ideally, you need to create a single difference between two groups that are otherwise the same. Thinking Straight about Psychology In this situation, one company (the Lambeth Company) had moved upstream of n the Thames after the last cholera outbreak in order to escape the sewage. The Southwark & Vauxhall Company, however, stayed downstream. The probability was that the water of the Lambeth Company was much less contaminated than the water of the Southwark & Vauxhall Co. Snow confirmed this by chemical testing. All he had to do now was calculate the death rates for the houses supplied by the two water companies. The rate for the Lambeth Co. was 37 deaths per 10,000 households, compared to a rate of 315/10,000 for the Southwark & Vauxhall Co. This finding lent strong evidence that water contamination was the source of cholera. Scientific thinking is based on the ideas of  Comparison  Control  Manipulation Scientists have to compare data patterns under different conditions in order to rule out certain explanations and confirm others. They construct their comparisons so the outcome will eliminate as many alternative explanations as possible. They do this by either directly controlling the experimental situation or by observing the kinds of naturally occurring situations that allow them to test alternative explanations. Most of the time, scientists are not as fortunate as Snow was (who found a naturally occurring manipulation). They have to manipulate the variable believed to be the cause while keeping all other variables constant. The best experimental design is one in which the experimenter manipulates the variable of interests and controls all of the other extraneous variables affecting the situation. Snow did not do this because subjects were not randomly assigned to which water company serviced their house. At some point (years earlier), they had chosen one water company over the other. We can’t rule out the possibility, however remote, that there were systematic differences involved in choosing the water company. 8 The Case of Clever Hans, the Wonder Horse: In the early 20th century, a German schoolteacher supposedly trained a horse to solve math problems (addition, subtraction, multiplication, and division). The horse was observed by many people, including “experts,” solving the problem correctly. Finally, a psychologist named Oskar Pfungst decided to test the horse’s ability in a systematic way. He manipulated situations in which the horse performed, which allowed alternative explanations of the horse’s performance to be tested. Pfugst found that the horse was watching the trainer’s head bob unconsciously as it was tapping out its answer. When the horse was approaching the correct number of taps, the trainer’s head would involuntarily tilt his head slightly. The horse picked up on that. He was clever, but not in math. The lesson here is that the cause of an event does not logically follow from the observation of it. Facilitated Communication in Autism: In the 1990s, a technique came out of Australia that supposedly helped nonverbal autistic kids to speak. It was called facilitated communication and involved a facilitator propping the kids’ arms and hands on a typewriter, allowing them to type out messages. The approach was praised on 60 Minutes, Parade magazine, and The Washington Post. Kids who had never been exposed to the alphabet were now somehow typing out highly literate prose. Carefully controlled studies revealed that the autistic child’s performance depended on tactile cuing of the experimenter, resembling the Clever Hans case. One situation was set up in which both the child and the facilitator were presented with a drawing of an object. They could not see the other’s drawing. When both the child and facilitator were looking at the same drawing, the child typed the correct name of the drawing. But when the child and facilitator were shown different drawings, the child typed the name of the facilitator’s drawing, not the one in which he was actually looking at. Thus, the facilitator, not the child, was controlling the responses. In an even worse twist, at some centers were facilitated communications were used, charges of sexual abuse by parents during “facilitated” sessions were made. Children started being removed from parents’ homes for groundless reasons. Court-ordered validations found that the facilitator was influencing the responses. Yet another example of pseudoscience harming the public. 9