94 Chapter 5
Aphasia and Agnosia
Broadly defined, agnosia is a perceptual disorder in which the patient is unable to recognize
salient features of a sensory stimulus. It can be caused by damage to several areas of the brain,
especially the thalamus, a structure that is sometimes called the gatekeeper and is impor tant to
perception. Agnosia can affect any of the five senses, but vision and hearing are most relevant to
aphasia. Unlike aphasia, which impairs, more or less, all modalities of communication, agnosia
is usually limited to one modality. For example, a patient with visual agnosia may have difficulty
recognizing letters and other graphemes visually, but knows them when they are spoken or traced
on his or her hand. In visual agnosia for objects, a patient puts a knife in a glass of water to use it
as a straw; visually, he or she does not appreciate the utensil’s significance.
Auditory agnosia is impairment of information coming from the sense of hearing and includes
speech and nonspeech stimuli. Acoustic agnosia is misperception of the differences in the salient
aspects of speech sounds. A patient with auditory agnosia might misperceive the ring of a tele-
phone, a knock at the door, or the high- pitched, steady tone of a smoke alarm— picking up the
telephone at the sound of a knock at the door, ignoring a visitor’s beckoning at the door, and failing
to leave a room when an alarm goes off. In auditory agnosia, the patient misperceives or does not
appreciate the significance of environmental sounds. In acoustic agnosia, the auditory discrimina-
tion prob lems are related to speech sounds, with or without environmental sound misperception.
Individual speech sounds are not distinguishable, especially those that are acoustically similar.
Because it is clinically difficult to diagnose and treat the two disorders separately, in this book
perceptual disorders related to the sense of hearing are called auditory- acoustic agnosia.
Aphasia and Abstraction
Because language is impor tant to thinking, the question may arise: What role does aphasia play
in intelligence? Neuropsychological tests often reveal that the patient with aphasia has a reduced
verbal intelligence quotient, but per for mance scores are usually only moderately reduced or within
the normal range. Although aphasia does disrupt or eliminate language, it does not reduce the
patient to the mental status of a child, nor does he or she have intellectual disability or dementia.
Most patients remember life experiences and can pro cess information using nonlanguage modali-
ties. However, it would be misleading to suggest that a patient’s cognitive abilities are unaffected
by aphasia. Early research on the cognitive abilities of patients with aphasia showed that they tend
to use concrete thinking (Goldstein, 1948, 1952). In his classic articles on aphasia and cognition,
Goldstein called this condition abstract- concrete imbalance. Patients with aphasia tend to function
on a concrete level for verbal abilities, as expected, and for nonverbal tasks as well. For example,
when sorting tokens of vari ous shapes, colors, and sizes, these patients, particularly those with
severe aphasia, tend to be concrete and have prob lems knowing the categories.
Psychological Concomitants of Aphasia
Although there are individual variations in the way persons react to brain damage, stress, loss,
and disability, de cades of research have shown common psychological reactions in patients with
aphasia (Tanner, 2016). These include catastrophic reactions, perseveration- echolalia, organic
depression, a grief response to loss, and emotional lability (Tanner, 2003a, 2003b). Not all patients
with aphasia experience all of these reactions, and some, particularly those with mild and revers-
ible aphasia, are spared significant reactions. Many of the psychological concomitants of aphasia
are short lived; others, such as organic depression, may be long lasting. Some of the difficulty
persons with aphasia have adjusting to aphasia is a result of lost or impaired verbal defense mecha-
nisms and coping styles (Tanner, 2003d, 2012).