Behavioral measures of primary consciousness can be either objective or subjective. Regarding objective measures, knowledge is unconscious if it expresses itself in an indirect test. For example, the ability to pick which item might come next in a series can indicate unconscious knowledge of regularities in sequences. "Strategic control measures" use a person's ability to deliberately use or not use knowledge according to instructions. If they use information despite intentions not to use it, it indicates unconscious knowledge. Post-decision wagering can also be used. In this method, subjects make a first-order discrimination (i.e. a choice) and then place a wager regarding the outcome of the discrimination. Some scientists view this as a direct and objective measure of consciousness, and it can be used with children and animals. However, this method has been argued to be subjective and indirect.
