Normally, there will not be a shift in the demand curve when ____________.

In economic theory, a distinction is made between a 'shift' in the demand curve and a 'movement along' the curve. A shift occurs when non-price determinants change, such as consumer preferences, average income [1], or population size. For instance, an increase in income or population shifts the entire demand curve rightward because consumers are willing to buy more at every price level. Conversely, a change in the price of the commodity itself does not shift the demand curve. Instead, it causes a movement along the existing demand curve, referred to as an expansion or contraction of quantity demanded [2]. Therefore, when the price of a commodity falls, it results in a downward movement along the same curve rather than a shift [2].

Sources

1. [1] Microeconomics (NCERT class XII 2025 ed.) > Chapter 2: Theory of Consumer Behaviour > 2.4.5 Shifts in the Demand Curve > p. 25
2. [2] https://www.khanacademy.org/economics-finance-domain/microeconomics/supply-demand-equilibrium/market-equilibrium-tutorial/a/changes-in-equilibrium-price-and-quantity-the-four-step-process-cnx