Blinded study: “A study done in such a way that the patients or subjects do not know (is blinded as to) what treatment they are receiving to ensure that the results are not affected by a placebo effect (the power of suggestion).”
Demand Characteristics: "In a psychological experiment, a demand characteristic is a subtle cue that makes participants aware of what the experimenter expects to find or how participants are expected to behave. Demand characteristics can change the outcome of an experiment because participants will often alter their behavior to conform to expectations." How to overcome demand characteristics: (a) deception (tell participants your looking for one thing when you're really looking for another), (b) double-blind study.
Double-blind study: "neither the participants nor the experimenters know who is receiving a particular treatment." Used to prevent bias due to demand characteristics or placebo effect. (How do you pull this off in most psychological experiments?)
Experimenter bias: when researchers unknowingly influence "the results during the administration or data collection stages of the experiment. Researchers sometimes have subjective feelings and biases that might have an influence on how the subjects respond or how the data is collected." For examples, see below.
Null result: result without the expected outcome.
Observational study: researcher is not allowed to decide which group/treatment participants select.
Placebo effect: “Doctors have long noticed that people tend to get better whenever they take a treatment they believe might help them. Even treatment with placebo—a nonmedicinal substance such as a sugar pill—can make people feel better if they believe it is medicine. Also, when people believe they are taking an effective treatment, they may be more conscientious about taking other steps that can help them, such as improving their diet and increasing exercise. This can produce benefits even if the treatment itself is ineffective.”
Regression to the mean: "The get-better-anyway effect has a technical name, regression to the mean... [W]hen you think about it, it’s simply common sense. You tend to go for treatment when your condition is bad, and when you are at your worst, then a bit later you’re likely to be better [and thus conclude that the treatment is what made you better]."
Sham treatment: "Placebos are inactive substances used to compare results with active substances. And in sham treatments, the doctor goes through the motions without actually performing the treatment."
Size: “Don’t accept claims of efficacy/effectiveness based on underpowered randomized trials. Dismiss them. The rule of thumb is reliable to dismiss trials that have less than 35 patients in the smallest group. Over half the time, true moderate sized effects will be missed in such studies, even if they are actually there.”
Null result: result without the expected outcome.
Observational study: researcher is not allowed to decide which group/treatment participants select.
Placebo effect: “Doctors have long noticed that people tend to get better whenever they take a treatment they believe might help them. Even treatment with placebo—a nonmedicinal substance such as a sugar pill—can make people feel better if they believe it is medicine. Also, when people believe they are taking an effective treatment, they may be more conscientious about taking other steps that can help them, such as improving their diet and increasing exercise. This can produce benefits even if the treatment itself is ineffective.”
Regression to the mean: "The get-better-anyway effect has a technical name, regression to the mean... [W]hen you think about it, it’s simply common sense. You tend to go for treatment when your condition is bad, and when you are at your worst, then a bit later you’re likely to be better [and thus conclude that the treatment is what made you better]."
Sham treatment: "Placebos are inactive substances used to compare results with active substances. And in sham treatments, the doctor goes through the motions without actually performing the treatment."
Size: “Don’t accept claims of efficacy/effectiveness based on underpowered randomized trials. Dismiss them. The rule of thumb is reliable to dismiss trials that have less than 35 patients in the smallest group. Over half the time, true moderate sized effects will be missed in such studies, even if they are actually there.”
Uncontrolled study: all participants given the treatment, no comparison group. These studies can tell us if the treatment has side effects, but they can’t tell us if the intervention causes improvement, as the placebo effect ensures that most of the participants will improve.
* * * * *
Examples of experimenter bias:
Robert Rosenthal is most known for his research and studies conducted on experimenter expectancy effects, which is the influence that a researcher can have on the outcome of an experiment (“Rosenthal’s Work”, n.d.). The first notable study that he worked on was with Fode in 1963. Rosenthal and Fode had two groups of students test rats; these rats were categorized as being bred “maze bright” or “maze dull,” even though, in reality, they were all standard lab rats and not specially bred one way or the other. The results of the study illustrated that the students unconsciously influenced the performance of the rats in order to fit the expected results between the “maze bright” and “maze dull” rats (“Rosenthal’s Work”, n.d.). Thus, Rosenthal would rationalize that the same effect would occur with teachers and students.
Rosenthal’s most famous study was conducted with Lenore Jacobson in 1963 at an elementary school just south of San Francisco, California (Spiegel, 2012). His purpose was to figure out what would ensue if teachers would react differently towards certain students if told that a select number of students were expected to learn more information and more quickly than the pupils in their class. To test this, Rosenthal issued a Test of General Ability to the students in the beginning of the year (“Rosenthal’s Work, n.d.). After the students had completed this IQ test, some were chosen at random to be the students that were expected to academic bloomers; however, the results of the test did not influence which students of the class were chosen (Bruns et al., 2000). He continued to observe the interactions between teachers and students and decided to issue another IQ test at the end of the study to see how IQ has improved in students that were to be academic bloomers versus the control group (Spiegel, 2012).
Rosenthal’s and Jacobson’s results had reinforced their hypothesis that the IQs of the “academic bloomers” would in fact be higher than those of the control group even though these academic bloomers were chosen at random (Bruns et al., 2000). Especially in younger children like those in grades 1 and 2, there was a remarkable difference in the increases of IQ between the students chosen to be academic bloomers and those that were not. A reason for this is because younger children may be able to be influenced more greatly by their teachers, who are respected authorities (“Rosenthal’s Work”, n.d.).
The conclusions demonstrated by the study greatly illustrate the Pygmalion effect, or Rosenthal effect, which is the phenomenon that explains better performances by people when greater expectations are put on them (Bruns et al., 2000). For example, the teachers in the study, may have unnoticeably given the supposed academic bloomers more personal interactions, highly extensive feedback, more approval, and kind gestures, such as nods and smiling (Spiegel, 2012). On the other hand, teachers would generally pay less attention to low-expectancy students, seat them farther away from teachers in the classroom, and offer less reading and learning material (Bruns et al., 2000).
* * * * *
Salvaging psychotherapy research: a manifesto
Chambless, D. L., & Ollendick, T. H. (2001). Empirically supported psychological interventions: Controversies and evidence. Annual review of psychology, 52(1), 685-716. They offer EBT guidelines.
* * * * *
Examples of experimenter bias:
Robert Rosenthal is most known for his research and studies conducted on experimenter expectancy effects, which is the influence that a researcher can have on the outcome of an experiment (“Rosenthal’s Work”, n.d.). The first notable study that he worked on was with Fode in 1963. Rosenthal and Fode had two groups of students test rats; these rats were categorized as being bred “maze bright” or “maze dull,” even though, in reality, they were all standard lab rats and not specially bred one way or the other. The results of the study illustrated that the students unconsciously influenced the performance of the rats in order to fit the expected results between the “maze bright” and “maze dull” rats (“Rosenthal’s Work”, n.d.). Thus, Rosenthal would rationalize that the same effect would occur with teachers and students.
Rosenthal’s most famous study was conducted with Lenore Jacobson in 1963 at an elementary school just south of San Francisco, California (Spiegel, 2012). His purpose was to figure out what would ensue if teachers would react differently towards certain students if told that a select number of students were expected to learn more information and more quickly than the pupils in their class. To test this, Rosenthal issued a Test of General Ability to the students in the beginning of the year (“Rosenthal’s Work, n.d.). After the students had completed this IQ test, some were chosen at random to be the students that were expected to academic bloomers; however, the results of the test did not influence which students of the class were chosen (Bruns et al., 2000). He continued to observe the interactions between teachers and students and decided to issue another IQ test at the end of the study to see how IQ has improved in students that were to be academic bloomers versus the control group (Spiegel, 2012).
Rosenthal’s and Jacobson’s results had reinforced their hypothesis that the IQs of the “academic bloomers” would in fact be higher than those of the control group even though these academic bloomers were chosen at random (Bruns et al., 2000). Especially in younger children like those in grades 1 and 2, there was a remarkable difference in the increases of IQ between the students chosen to be academic bloomers and those that were not. A reason for this is because younger children may be able to be influenced more greatly by their teachers, who are respected authorities (“Rosenthal’s Work”, n.d.).
The conclusions demonstrated by the study greatly illustrate the Pygmalion effect, or Rosenthal effect, which is the phenomenon that explains better performances by people when greater expectations are put on them (Bruns et al., 2000). For example, the teachers in the study, may have unnoticeably given the supposed academic bloomers more personal interactions, highly extensive feedback, more approval, and kind gestures, such as nods and smiling (Spiegel, 2012). On the other hand, teachers would generally pay less attention to low-expectancy students, seat them farther away from teachers in the classroom, and offer less reading and learning material (Bruns et al., 2000).
* * * * *
Salvaging psychotherapy research: a manifesto
Chambless, D. L., & Ollendick, T. H. (2001). Empirically supported psychological interventions: Controversies and evidence. Annual review of psychology, 52(1), 685-716. They offer EBT guidelines.
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