Sample response

Psychologists in the biological approach often use experiments to establish cause-and-effect relationships.  An experiment allows researchers to manipulate an independent variable and measure its effect on a dependent variable while keeping other variables constant. In addition, participants are randomly allocated to conditions.  Finally, in biological research, a placebo is often given as a way of preventing demand characteristics.  A placebo is when participants believe that they are getting a treatment, but they are not.

An example of this was a study by Newcomer who wanted to see the effect of stress on verbal declarative memory. When we are stressed we secrete a hormone called cortisol. Newcomer’s hypothesis was that high levels of cortisol would prevent memory formation. To test the hypothesis, participants were randomly allocated to one of three conditions: a low dose of cortisol, a high dose of cortisol or a placebo – a pill that they thought was cortisol but was not. The experiment took place over 10 days with four different measures of the participants’ ability to immediately recall a piece of prose that was read to them.  The experiment was a double-blind study- the participants did not know which group they were in and the researcher also did not know which participants had been assigned to each group. 

The results showed that the group that received the high does of cortisol had the lowest recall of details from the prose passage. From the manipulation of the IV, the researchers may conclude that it was the level of cortisol that actually affected their ability to form verbal declarative memories.

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