Involuntary action. An involuntary action is one which occurs without the conscious choice of an organism. If it occurs specifically in response to a stimulus, it will be known as a reflex. Involuntary actions are opposite of voluntary actions that occur because of choice. Involuntary actions may or may not occur with the awareness of the organism performing it. Common involuntary actions displayed by humans and most other mammals are heartbeat, hic-ups, digestion, coughing and sneezing.