Double take: Oliver and James as the Weasley twins in the 2003 film Harry Potter And The Prisoner Of Azkaban surrounded by their co-stars. Identical: James, left, and Oliver Phelps arrive at London's Odeon Leicester Square for the world premiere of 'Harry Potter and the Chamber of Secrets' in 2002.
An increase in demand is represented by a shift of the demand curve to the right: A decrease in from ECON 101 at Universitat Pompeu Fabra
Factors. A demand curve can shift to the left for a wide variety of reasons. A negative product review can reduce consumer demand for an item, shifting the demand curve to the left. Similarly, a government health warning about an item also can reduce demand and shift the curve. Simple competition also can cause the demand curve to shift left, as consumers stop buying one product in favor of a newer, more desirable item.