Exam 7: External Validity of Laboratory Experiments

Describe the concept of demand characteristics, and provide one example of a demand characteristic in a study with perception of the threat of physical harm (high, low) as the IV and aggression as the DV. In your response, be sure to (a) describe demand characteristics; (b) provide your example; and (c) explain how your example reflects a demand characteristic in the context of the threat-aggression study.

Researchers wanted to investigate the effects of having plants in the laboratory (plants present, plants absent) and giving participants a snack prior to participating (cookie, carrots) influenced participants' aggressiveness after completing 30 minutes of a tedious and seemingly unending task (e.g., rotating each of 64 dowels in a grid a quarter-turn, and when finished, repeating the process). Which of the following could be considered demand characteristics in the context of this study? (circle all that apply)

Explain what it means to have a nonrepresentative sample. Describe the situations where a pool of such participants risks dramatically limiting the extent to which results can be generalized to the rest of the population, and when using such participants is unlikely to influence results much, if at all. Provide an example study (i.e., list of 1 IV and 1 DV) that would be vulnerable to nonrepresentative-participant bias, as well as an example study that would not be vulnerable to this bias, and be sure to explain why and how those examples demonstrate what you claim that they are demonstrating.

What is meant by Webber and Cook's (1972) categories of participants (i.e., good, negative, faithful, apprehensive)? How do these relate to voluntary, involuntary, and nonvoluntary participants? Relate these two models of participants. In your response, be sure to (a) briefly define each term, and (b) explain how Webber and Cook's categories would correspond with the degrees of "voluntary" participation.

Experimenter expectancy bias:

What are some ways to reduce the possibility of experimenter expectancy effects?

Which of the following would NOT be an effective means of avoiding experimenter bias:

Which types of participants are likely to yield the greatest degree of generalizability or external validity? (circle all that apply)

Participants bring many things with them to participate in a lab experiment. How can the experiences of a participant influence the course of a study? Consider types participants (e.g., good, faithful) and factors within the experiment itself (i.e., demand characteristics).

If a participant believes that the treatment they have received will cause anxiety, and thus they report higher levels of anxiety, this is an example of:

_________ and _________ participants are most likely to threaten the generalizability of a laboratory study:

Describe the three major aspects of external validity. How do they differ, and how are they similar? What aspects of a study's findings does each "face" address? In your response, be sure to (a) define each aspect, (b) explain how each aspect is similar and/or different from the others, and (c) describe what about a study would be externally valid if it were high in each aspect of external validity.

You have developed a new form of behavioral therapy for people with various conduct disorders, and you think it is a relatively robust treatment. Specifically, the therapy has been successful when it was practiced in your private clinical office and in a public park, and it has been successful across various age groups (e.g., children, teens, middle-age, seniors). However, whenever another researcher tries to replicate your treatment implementation, or when individuals attempt to reproduce what they have seen you do on television, no one seems to be able to achieve the same levels of success that you do (and your argument is that others have less success because "they aren't doing it right"). That is not to say your results are fabricated; indeed, your therapy works, just only when you administer it. In this example, how would you classify the validity and generalizability of your behavioral therapy? Is it an externally valid therapeutic technique if only you can implement it successfully? How generalizable is it?