Right hemisphere brain damage (RHD) is the result of injury to the right cerebral hemisphere.American Speech-Language-Hearing Association. (2015). Right hemisphere brain damage. Retrieved from http://www.asha.org/public/speech/disorders/RightBrainDamage/ The right hemisphere of the brain coordinates tasks for functional communication, which include problem solving, memory, and reasoning. Deficits caused by right hemisphere brain damage vary depending on the location of the damage.Brookshire, R. H. (2007). Right hemisphere syndrome. In K. Falk (Ed.), Introduction to Neurogenic Communication Disorders (7th ed., pp. 391-443). St. Louis, MO: Mosby Elsevier.
Signs and symptoms
Visual processing Individuals with right hemisphere damage exhibit deficits in visual processing. They are only able to recognize the right half of a picture, symbol, or text. rather than seeing the concept as a whole. In a now widely replicated experiment, individuals with RHD showed an inability to grasp the whole of a given concept. These individuals were told to recreate an image of many small triangles making up the shape of an M. Their replications succeeded in depicting the triangle, but their arrangement of triangles was random, and evidently they only grasped the parts, and not the whole structure. Individuals with RHD also seem to struggle with inference revision, indicating an inability to drop focus, once given to a particular concept. In an experiment by Bloise and Tompkins, RHD individuals performed markedly worse at revising an inference they had about a paragraph when new information was presented that made their reading wrong. This was a sort of garden path paragraph, that RHD individuals had a hard time grasping.
Cognitive and communicative General
Patients with right hemisphere brain damage most commonly have difficulties with attention, perception, learning, memory, recognition and expression of emotion, and neglect. Other frequently occurring, though slightly less common, deficits include reasoning and problem solving, awareness, and orientation. It is also common for patients with right hemisphere damage to have a flat affect, lack of emotional expression, while speaking. Additionally, these patients commonly have difficulty recognizing other people's emotions when expressed through facial expressions and tone of voice. This lack of ability to recognize emotion suggests individuals have an impaired theory of mind, the ability to recognize the thoughts and feelings of others outside of one's self. Although these deficits alone may complicate therapy, the patient may also exhibit anosognosia, or ignorance of his or her impairments. Due to possible anosognosia, it is common for patients to not become frustrated or upset when they are unable to complete tasks they were previously able to complete.
Unlike those of people with aphasia, the speech patterns of individuals with right hemisphere damage are not typically characterized by "word finding problems, paraphasias, circumlocutions, or impaired phonological processing." Circumlocution in persons with RHD tends to center around general concepts, not specific words. For example, in describing what brought a RHD-affected individual to the hospital, though the patient would likely remember the word "stroke" and other specific words to describe his situation, the RHD impairment to his discourse level and cognitive processes would likely prevent him from describing the situation in a coherent manner.
Linguistic impairments
Syntax
The syntax of RHD-affected individuals tends to be "accurate and varied"; unlike people with aphasia, they tend not to have difficulty with word retrieval. In addition, people with right hemisphere damage usually understand the literal meaning of most statements. Linguistically, in cases in which RHD patients seem to have syntactic deficits, they are typically the result of problems with semantic processing.
Semantics
In a 1962 study, Eisenson observed a "looseness of verbalization" in RHD-affected individuals, noting that right hemisphere damage appears to affect "relatively abstract language formulations." According to Eisenson, this is evidence that the right hemisphere likely controls "super- or extra-ordinary" language function. In other words, RHD patients have trouble with higher-level language tasks (relating to semantic and lexical processing) less common in day-to-day, average discourse. In describing semantic deficits in persons with right hemisphere damage, a distinction must be drawn between convergent and divergent semantic processing. Tasks involving convergent semantic processing ("relatively straightforward linguistic tasks in which the number of responses is limited"), which involve the most straightforward meanings of words, are not nearly as difficult for RHD patients as tasks involving divergent semantic processing (tasks that "elicit a wide range of meanings which may diverge from a single semantic concept to include non-dominant meanings that are alternate, connotative, and/or less familiar").
In terms of convergent semantic processing, people with RHD do not demonstrate semantic impairment at the phonemic level, nor do they tend to have difficulty understanding the primary meanings of individual words. Their comprehension of simple, unambiguous sentences also remains intact, as does their basic word retrieval; this evidence suggests that these tasks are functions of the left hemisphere. On the other hand, the right hemisphere is more involved in recognizing multiple and non-primary meanings of words, divergent semantic processing tasks that are impaired in individuals with right hemisphere damage. Along these lines, RHD patients experience difficulty with verbal fluency; in an experiment in which RHD-affected individuals were asked to name items within a category, they tended to suggest objects connected in more ways than one (with many characteristics in common). For example, when asked to name vegetables, people with RHD would name spinach, cabbage, and lettuce, which share the attributes not only of being vegetables but also of being "green and leafy." Such results "support a model of semantic processing in which the [right hemisphere] is superior in generating multiple, loosely connected meanings with little overlap," a function clearly affected by right hemisphere damage.
As a result of pragmatic deficits, individuals with right hemisphere damage have a hard time understanding the figurative cues in language and tend to simply understand sentences from their literal meanings. For instance if someone were to say, Joey took the lion's share, they would assume Joey took the portion that belonged to the lion as opposed to the colloquial meaning-the majority. On the same vein, they also do not understand pragmatics and the underlying clues language might have. Because of this, implicit commands or suggestions in sentences are lost on people with right hemisphere damage. In addition, they have a hard time staying on topic during a conversation and therefore show a deficit in topic maintenance. Some however may stick to the main topic, but bury it in their speech with a large amount of detail that is not relevant to the main point. They also tend to show a lack of awareness for the knowledge they share with those they are communicating with and will mention people or things for which others do not have a reference.
Discourse impairments
Considering the highly contextual and often ambiguous nature of discourse, it tends to be the area of communication most affected by right hemisphere damage. RHD is particularly evident in the inference patterns of affected individuals. Though RHD patients are typically capable of making basic inferences about situations, more subtle inferences key to discourse and conversation are often severely impaired. As Penelope Myers notes, much empirical research has shown that persons with right hemisphere damage are "significantly impaired in generating inferences about individual elements of pictured scenes," and, most significantly, in compiling information about the individual elements together to understand the situation at-large. This impairment also applies to written or spoken text. For example, Beeman (1993) cites a patient who mentioned his ability to read "straightforward texts" but noted that he had stopped reading novels with multiple characters as, in the patient's words, "I can't put it all together."
Experimentation with Norman Rockwell paintings
As further evidence of this phenomenon, there has been research done with right hemisphere damaged patients using Norman Rockwell pieces. In these experiments, participants are shown a painting, without the title attached, and are asked to describe what is happening in the scene. As can be expected, there are variances between the answers of people with right hemisphere damage and no brain damage. These experiments have provided further evidence for the idea that individuals with right hemisphere damage have a hard time recognizing emotions of others as they do not mention them when asked to describe the paintings. In addition, this process has suggested that they do not pick up relevant cues and have difficulty incorporating the small details they do notice together to form a big picture. When actually describing the paintings, patients either give the experimenter too much description of what is happening, without addressing the overall theme of the piece, or provide them with a very basic one sentence description about what they see. After analyzing and comparing the descriptions of participants with no brain damage and those with right hemisphere damage, the researchers found that those with right hemisphere damage used twice as many words than those without brain damage even after the researchers took out the part of the descriptions that appeared to be tangential.
Furthermore, RHD-affected individuals experience deficits in inference-revision capabilities. As an example [from Brownell et al. (1986)], when presented with the sentence, "Barbara became too bored to finish the history book," both RHD subjects and control subjects assumed Barbara was reading the book. However, when subjects were then presented with a second sentence, "She had already spent five years writing it," control subjects altered their initial inference, whereas RHD subjects demonstrated great difficulty revising their inferences and drawing a broad, revised conclusion about the information at hand. RHD patients' difficulty with understanding non-literal meanings is also a significant cause of discourse impairment. As noted above, right hemisphere damage affects understanding of figurative language such as idioms, as a result of the right hemisphere's role in activating non-literal and peripheral meanings. As a result of their difficulties understanding alternate meanings and making situational inferences, people with right hemisphere damage face significant challenges in terms of discourse.