Cognitive inertia refers to the tendency for beliefs or sets of beliefs to endure once formed. In particular, cognitive inertia describes the human inclination to rely on familiar assumptions and exhibit a reluctance and/or inability to revise those assumptions, even when the evidence supporting them no longer exists or when other evidence calls them into question. The term is employed in the managerial and organizational sciences to describe the commonly observed phenomenon whereby managers fail to update and revise their understanding of a situation when that situation changes, a phenomenon that acts as a psychological barrier to organizational change.This can be seen in cases where people or students still carry big books to school without knowing that all they need is inside the phone they are holding. This can also be demonstrated in the case of people who generally resist changes except if such changes entail complementary additions to their already held set of beliefs. Cognitive inertia refers to the tendency for beliefs or sets of beliefs to endure once formed. In particular, cognitive inertia describes the human inclination to rely on familiar assumptions and exhibit a reluctance and/or inability to revise those assumptions, even when the evidence supporting them no longer exists or when other evidence calls them into question. The term is employed in the managerial and organizational sciences to describe the commonly observed phenomenon whereby managers fail to update and revise their understanding of a situation when that situation changes, a phenomenon that acts as a psychological barrier to organizational change.This can be seen in cases where people or students still carry big books to school without knowing that all they need is inside the phone they are holding. This can also be demonstrated in the case of people who generally resist changes except if such changes entail complementary additions to their already held set of beliefs. Cognitive inertia in business is most commonly seen in product development and marketing. Once a business becomes established, it will often ignore the competitive space until it has changed so completely it can no longer adapt products to match the new environment. Firms will also only market to one demographic and lose potential customers because they do not fit into its original views. In this way, some observers view cognitive inertia as associated with the concept of loss aversion where organizations would prefer to avoid loss than to achieve gain. One example of cognitive inertia concerns the judgment of the management of the Polaroid corporation that they could not make money on hardware but only on consumables, This led them to neglect digital imaging technologies. The once-successful company failed to adapt effectively to market changes and thus lost revenue and ultimately declared bankruptcy. In the 1980s the vacuum industry displayed cognitive inertia as they kept making similar models until Dyson revolutionized the industry by introducing a bagless vacuum. Once a belief is well-established, it is very difficult for cultures to overcome it until evidence forces them to do so. This was the case during the Spanish Influenza epidemic in the United States (1918-1919). Many Americans did not believe that an influenza they (mistakenly) though was from Spain could affect them until a large portion of the country was already infected. In the more modern period, there is an emerging position that anthropogenic climate change denial is a kind of cognitive inertial. Despite the evidence provided by scientific discovery, there are still those - including nations - who deny its incidence in favor of existing patterns of development. Not all instances of cognitive inertia are negative. Cognitive inertia is a fundamental component of love, trust and friendship. Once cognitive inertia is established, it provides an additional level of trust in a relationship. Cognitive inertia supports societal norms such as incest aversion.