In perspectomic terms, schemas are systems which emerge from collections of heuristics, and units which collect with other schemas into modes.
“In ordering life experiences, individuals need to determine what is important, construe it properly, and respond appropriately. The role of schemas is to process everyday stimulus situations in order to provide meaning and, depending on the content, engage other systems such as motivational, affective, and physiological systems. The concept of schemas was initially proposed by Piaget & Warden (1926) as the underlying structure for organizing perceptions of the world. Bartlett (1932) demonstrated that culturally based schema can distort memories. Kelly (1955) applied the notion of personal construct to the understanding and therapy of clinical problems. Although not explicitly using structure in his theory, Ellis (1958) introduced the concept of beliefs in terms of assigning meaning to events. Negatively biased schemas, or those schemas that are theorized to have a causal role in the development of mental disorders such as depression and anxiety (Beck 1967), develop through a complex biasing process involving the interaction of genetic factors, selective allocation of attentional resources and storage in memory with adverse environmental life events.”
— from Advances in Cognitive Theory, Aaron T. Beck and Emily A.P. Haigh (2014)