Implications of Skinner's Verbal Behavior for Studying Dementia

Overview of Dementia "Dementia" is a generic term that describes the progressive decline in a number of cognitive abilities such as attention, memory, language, perception, and reasoning that interferes with daily functioning (APA, 2000). Dementia can also result in behavioral changes such as wandering or aggression, declines in self-care skills, and mood disturbances such as depression or anxiety. Dementia can be caused by a number of different, irreversible causes (e.g., Alzheimer's disease, vascular disease, Pick's disease) as well as reversible causes (e.g., vitamin B12 deficiency, medication overdose). Dementia is a serious public health concern in the United States. If one considers all causes of dementia, approximately 6-10% of individuals over the age of 65 suffer from dementia, with Alzheimer's Disease (AD) accounting for approximately 65% of all cases (Hendrie, 1997). Age is the number one risk factor for developing dementia, which is particularly concerning given the rapidly aging population of the United States. It is projected that 13 to 15 million Americans could suffer from AD alone by the year 2050 if no cure is found (Hebert, Scherr, Bienias, Bennet, & Evans, 2003). Language deficits associated with dementia. Language deficits (i.e., aphasia) associated with dementia can take on various forms/topographies, including receptive and expressive language deficits. Language deficits in the early stages of dementia are characterized by pronounced difficulties with speech production as opposed to comprehension (Levine, 2006). Common early stage deficits include word finding deficits (i.e., anomia), poor spontaneous writing, indefinite references ("it", "those", or "thing"), repetition of words or ideas, and difficulty understanding complex language such as metaphors or analogies (APA, 2000; Kempler, 1991; Orange, 2001). As the disease progresses deficits such as empty content, inappropriate word substitutions, difficulties following multi-step commands, poor topic maintenance and inappropriate topic shifts, reduced reading comprehension, frequent digression from conversational topics, reduced verbal fluency, difficulties with turn-taking and producing fewer utterances per conversational turn (APA, 2000; Kempler, 1991; Orange, 2001; Levine, 2006) become apparent. In the final stages of the disease, the patient may engage in echolalia, produce continuous streams of nonsensical language, or become mute (Orange, 2001). These language deficits have important everyday implications for patients, and caregivers, who have described communication deficits as one aspect of dementia with which it is particularly challenging to cope (Orange, 1991). The many implications of language deficits associated with dementia will be further described in the sections below. Skinner's Conceptualization of Verbal Behavior and Its Implications for Dementia Skinner (1957) distinguished and functionally defined 6 types of verbal behavior including the tact, mand, echoic, textual, intraverbal and autoclitic. To say that these are defined functionally means the categories are delineated according to the reinforcement relations that shaped and/or maintain them as operant responses, not according to any topographical property of the word(s). For example, the word "water" could be an example of any of the categories, depending upon the conditions that evoke the response. Shouting "Water!" whenever a river or lake is visible is a tact whereas the same, "Water!" emitted after an hour in warm sun, even if perfectly similar in tone, inflection, or all formal properties, is a mand, for it is controlled very differently, and has a much different ultimate function. With this critically important difference between the Skinnerian versus traditional analyses (that of grammarians, for example) in mind, the 6 categories are defined in the following sections along with a discussion of a seventh variable--the audience. …