May 15, 2012
Expectations, Previous Experiences Influence Perception Of Pain
Connie K. Ho for RedOrbit.com
For many people, pain and needles go hand in hand. They shudder at the thought of going to the dentist or the doctor because of those pointy items. A new study looks at these preconceived notions of pain and needles, looking specifically at how these thoughts can affect a patients´ experience. The project, completed by a group of German researchers, states that past experiences with needle pricks, combined with information received before having an injection, can influence pain experience.The new research is published in the May issue of the journal Pain.
"Throughout our lives, we repeatedly experience that needles cause pain when pricking our skin, but situational expectations, like information given by the clinician prior to an injection, may also influence how viewing needle pricks affects pain," noted lead author Marion HÃ¶fle, a doctoral student in the research Multisensory Integration group led by Dr. Daniel Senkowski of the Department of Psychiatry and Psychotherapy at CharitÃ© University Medicine Berlin, in a prepared statement.
In the experiment, study participants watched various clips while also receiving painful or painless electric stimuli that were administered on their hand. The clips included images of a needle pricking a hand, a Q-tip touching a hand, and a hand standing alone. The images were shown to the participants on a screen that was placed above the participants´ hand; it gave the participants the experience that the video image was their own hand.
According to the participants of the study, they felt varying degrees of pain. When they watched clips of needles pricking a hand, they sensed that their pain was more intense and unpleasant than when they saw images of the hand alone. As well, seeing the needle prick a hand was more painful for the participants than seeing a Q-tip touch a hand. These self-reported results from the participants were also aligned with increased activity in the autonomic nervous system. The researchers were able to measure this increase in autonomic nervous system activity by measuring pupil dilation responses. These results showed how previous experiences regarding needles could impact the users´ degree of pain when viewing needles.
The study also found that situational experiences or expectations could affect a person´s take on pain. Before the stimulation, scientists told participants that either the needles or the Q-tips were more related to painful electrical stimulation than non-painful electric stimulation. The researchers believed that, when they showed clips that highlighted pain (i.e. images related to needles), the participants reported having more pain than when they watched clips less associated with pain. This proved that having certain expectations of particular experiences regarding pain influenced the intensity of the pain patients´ had during treatment.
Overall, researchers came to understand that the study showcased new findings regarding pain and the expectation of pain.
"Clinicians may be advised to provide information that reduces a patient's expectation about the strength of forthcoming pain prior to an injection," commented HÃ¶fle, also of the CharitÃ© - UniversitÃ¤tsmedizin Berlin and the University Medical Center Hamburg-Eppendorf. “Because viewing a needle prick leads to enhanced pain perception as well as to enhanced autonomic nervous system activity, we've provided empirical evidence in favor of the common advice not to look at the needle prick when receiving an injection."