One of the characteristics of frontotemporal dementia is a condition known as “field dependency.” It is a condition of stimulus boundedness or utilization behavior where the patient acts in response to environmental affordances or demands rather than intentional goal-directed activity or internally-imposed constraints. The patient is unable to govern stimulus-driven action. Thus for example the patient may see somebody eating a bag of potato chips from across the room. The patient will walk up to that person and grab the bag of potato chips without asking permission or for that matter engaging in any interaction at all.
Patients with field dependency will lack “fluid intelligence,” which is the ability to reason moment-by-moment, problem solve, draw inferences, recognize patterns, calculate, reason abstractly, acquire new knowledge, understand relationships, use common sense judgment and find solutions especially to ambiguous problems. Decline in fluid intelligence results in slower processing time, that is, one needs more time to process and react to information. Field dependence on the other hand does not involve a decline in performance or diminution in capacity to carry out a task or function. Rather it redirects the intentional object of that activity in a manner determined primarily by the availability of non-cognitive resources and a prevalence of suggestions derived from the ecology of a real-world situation.
This syndrome first was identified by the physician F. Lhermitte in a 1986 article entitled “Human Autonomy and the Frontal Lobes. Part II: Patient Behavior in Complex and Social Situations: The ‘Environmental Dependency Syndrome,” Ann. Neurol. 19, 335 – 343. Prior to Lhermitte’s article imitation and utilization behavior had been described in terms of a simple interaction between an examiner and a patient and were interpreted as an excessive dependence on environmental cues. Lhermitte expanded on this by studying patients with focal unilateral frontal lobe lesions. Their behavior was “striking, as though implicit in the environment was an order to respond to the situation in which they found themselves.” They experienced a disorder of personal autonomy; their individual psychological traits influenced the way in which this loss of autonomy was expressed. Lhermitte proposed the term “environmental dependency syndrome” for this condition.
Lhermitte’s article is particularly interesting from the standpoint of philosophical psychology and theory of mind. In Being and Time one of Martin Heidegger’s key objectives was to establish that most of our circumspective interactions with the world have the exact format Lhermitte describes, though of course without frontotemporal dementia. For example if one wants to leave a room, one does not conceive of an intention to open the door, approach it, regard the door knob, then physically move it in a circular direction. Rather one responds to the doorknob’s affordances and non-consciously deploys it as a tool or mechanism to facilitate the accomplishment of an objective (a “for-the-sake-of-which,” albeit a minor one). These types of responses characterize one’s skillful coping with the demands, contingencies and exigencies of everyday life.
As described by the leading Heidegger scholar Hubert Dreyfus in his book Being-in-the-World (p. 93): “Phenomenological examination confirms that in a wide variety of situations human beings relate to the world in an organized purposive manner without the constant accompaniment of representational states that specify what the action is aimed at accomplishing.” In other words there is no need to postulate mental constructs such as “intentions.” Rather, we simply are absorbed in activity and situationally respondent. This type of interaction extraordinarily resembles Lhermitte’s analysis.