Adults and older children can be instructed to remain still and either close their eyes or fixate on a screen in order to obtain a period of resting physiology (i.e., quiet wakefulness). As noted in the Appropriate Task section, these procedures would be inappropriate for research with infants and young children. Developmental researchers define baseline as a period of quiet wakefulness/attention and use stimuli that are likely to elicit the same affective and cognitive state in the majority of participants. Common procedures for an infant baseline period include watching colorful balls move around a bingo wheel or watching someone blow bubbles. Toddlers and preschoolers, on the other hand, are typically shown abstract visual images or nonarousing video clips during the baseline phase. Thus, as with task design, it is important to use an age-appropriate baseline while also accounting for the influence of state changes and other artifacts.
