The Placebo Effect

Placebo Effect Introduction

http://www.youtube.com/watch?v=wsFTgirKXHk

4 mins

Real-life example

http://www.youtube.com/watch?v=I-Wy1AYQIW0 (9 mins)

Bias

Preconceived opinion/feeling about something

Must be eliminated because it can become a variable which can (falsely) affect the results of the experiment.

Do you believe in…

“The Power of Positive Thinking”?

What is bias, and why does it need to be reduced or eliminated in experiments?

The and the Placebo Effect

The Placebo Effect:A phenomenon in which ANY treatment (even if it’s fake) can sometimes improve a patient’s condition simply because the person had the expectation (bias) that it would be helpful.

Who can experience the placebo effect?

However, with animals, their human handlers can in fact cause them to experience a placebo effect simply because of their expectations and how they behave around the animals!!

The placebo effect generally takes place in humans. It is not expected in other organisms such as plants, birds, cats, monkeys or other organisms because their thinking is not as complex and they do not experience bias.

What exactly is a placebo?

It is a ‘fake’ treatment or inactive substance made to resemble the ‘real thing’ in some form. treatment like a pill, cream, injection or other forms of treatment made to appear exactly like a test medication, but without any active ingredients. The placebo will not have any effects.

Does the placebo effect need to be controlled in your experimental and control groups?

Yes, therefore many drug studies are placebo-controlled. If patients on the new drug show improvement over the placebo group, this helps support the conclusion that the drug is effective.

Using a placebo in a study means everybody gets some kind of treatment. Therefore it prevents bias from becoming an experimental variable and this makes the placebo effect a controlled variable.

Should the patients (or the doctors/researchers) in the study know which group they are in?

Usually no… If it is unknown which group is getting the real thing and which group is getting the fake treatment, then everyone in the study has the same opportunity to experience “the placebo effect”.

Blind Study: only the doctors/researchers know which patients receive the placebo.

Double Blind Study: neither the doctors/researchers nor the patients know who is receiving the placebo. (ex. Randomly assigned computer-generated groups; they find out after the results are collected who was in each group.) This eliminates bias on the part of the doctors/researchers. (If the researcher knows which group he gave the placebo to then he/she may have some bias).

Example

An experiment is conducted to determine the effectiveness of vitamin C on the speed of wound repair.

100 hospital patients with wounds called bedsores were selected for the study. 50 of the patients received 200 mg of vitamin C on a daily basis while the other 50 were given a placebo that did not contain vitamin C.

Which was the experimental group?

Which was the control group?

What was the placebo?

Which of the two groups may have experienced the placebo effect?

Patients receiving Vitamin C pill

Patients receiving fake “look-alike” sugar pill

The fake “look-alike” sugar pill

C) both

THEORIES

THEORY

A hypothesis that has gone through extensive testing by a variety of methods

Many, BUT NOT ALL, scientists agree with a proven hypothesis, and so it becomes a THEORY

Theories

Germ Theory Microorganisms cause disease

Natural Selection Organisms with favorable adaptations will survive and

reproduce to pass genes on to offspring

Evolution Changes in the genetic material of a population of

organisms from one generation to the next

Theories

They can be changed after extensive testing.

*In science, the word theory applies to:

a well-tested explanation that unifies a broad range of observations and hypotheses and that enables scientists to make accurate predictions about new situations.

Examples:Germ theory of disease ____Idea that

microorganisms cause disease. ________________

Theory of natural selection ___(Darwin) - Idea of Survival of the fittest __________________

Theory of evolution __Idea that groups of organisms change over time