CHAPTER 15

The Cognitive Neuroscience of Confabulation: A Review

and a Model

Asaf Gilboa and

Morris Moscovitch Baycrest Center for Geriatric Care, North York, Ontario, Canada

Confabulation may be defined as honest lying. The confabulating patient provides infor- mation that is patently false and sometimes self-contradictory without intending to lie. The patient is unaware of the falsehoods, and sometimes will cling to these false beliefs even when confronted with the truth. The patient's underlying false belief is conveyed not only by verbal statements but also by actions. The term "confabulation" is often loosely used to denote a wide range of qualitatively different memory phenomena. On the one hand, it is used to describe mild distortions of an actual memory, such as intrusions, embellish- ments, elaborations, paraphrasing or high false alarm rates on tests of anterograde amnesia (Kern et al., 1992; Kopelman, 1987; Rapcsak et al., 1998; Tallberg & Almkvist, 2001). On the other hand, it refers to highly implausible bizarre descriptions of false realities, such as claiming to be a pirate on a spaceship (Darnasio et al., 1985), being a pilot in Saddam Hussein's air force, forced to eject at 7000 meters and reaching the ground with no parachute (Feinstein et al., 2000), or watching members of one's family being killed (Stuss et al., 1978). Thus, Berlyne (1972) drew the distinction between momentary (or embarrass- ment) confabulations and fantastic (or productive) ones, the former being commoner, brief and of a variable true content that is displaced in time, the latter being more grandiose and stable in content, and appearing without provocation. Berlyne concluded that fantastic con- fabulations are a distinct entity, having nothing in common with momentary ones. Kopelman (1987) suggested that a more useful distinction is between spontaneous and provoked types of confabulations, the former being rare and related to an amnesic syndrome superimposed on a frontal dysfunction, while the latter represents a common, normal response to faulty memory.

Clinical observations suggest several characteristics of confabulations (Talland, 1965; Moscovitch, 1989):

The Handbook oJMemory Disorders. Edited by A.D. Baddeley, M.D. Kopelman and B.A. Wilson 'Q 2002 John Wiley & Sons, Ltd.