Convergent semantic processing
Convergent semantic processing occurs during tasks that elicit a limited number of responses. During these tasks, subjects must suppress alternate options in order to select a single best option from a multitude of choices. It is believed that the left hemisphere of the brain dominates convergent semantic processing due to the fine grained, small window of temporal integration. Spatially,Neurons in the left hemisphere
During semantic processing, the left hemisphere will prime for the dominant and the subordinate meaning of an ambiguous word (words are considered to be ambiguous when their semantic features separate into distinct semantic representations). The left hemisphere will then select the dominant or most relevant meaning of the word, and inhibit meanings that are less relevant or frequent. Despite activating subordinate meanings of the words, the left hemisphere shows no facilitation of them, and their activation decays very quickly. Compared to the right hemisphere, the left hemisphere activates a small semantic field and close semantic relationships strongly.{{cite journal , last1=Thompson , first1=H. E. , last2=Henshall , first2=L. , last3=Jefferies , first3=E. , date=2016 , title=The role of the right hemisphere in semantic control: A case-series comparison of right and left hemisphere stroke , journal=Neuropsychologia , volume=85 , pages=44–61 , doi=10.1016/j.neuropsychologia.2016.02.030 , pmc=4863527 , pmid=26945505 While convergent semantic processing and the activation of common word meanings and semantic features are advantageous for various linguistic tasks, the left hemisphere faces challenges in scenarios where the recognition of an ambiguous word requires the activation of multiple primes that can either converge into a subordinate meaning or diverge into incompatible meanings of the word. Studies of patients with left hemisphere damage have demonstrated a disruption of convergent semantic processing, causing subjects to associate words with abstract, non-literal meanings produced by the right hemisphere. For example, a subject with left hemisphere damage may affiliate the word “deep” with “wise” rather than its literal antonym “shallow.” However, damage to the Left Hemisphere will preserve summation priming. Semantic processing can also be affected by various health conditions such as semantic aphasia, which may be a result of a unilateral stroke to the left inferior frontal gyrus and posterior middle temporal gyrus. Individuals with semantic aphasia may struggle with controlled semantic retrieval. They may also show deficits in semantic tasks that have different retrieval demands.Examples of convergent processing
To test for convergent processing, an experimenter may instructs the subject to select an infinite verb that most accurately describes the function of each stimuli. For example, if the experimenter were to present the word “hammer,” the participant would have to suppress related meanings such as “to crush” or “to assemble,” and instead select the most familiar meaning, like “to pound.” Other examples of potential stimuli are below and the proper selection of their corresponding infinite verbs are below. ;Stimulus/Verb * Hammer --> To Pound * Needle --> To Sew, * Bat --> To Swing * Sponge --> To Scrub * Basketball --> To Shoot * Pencil --> To WriteDivergent semantic processing
Divergent semantic processing occurs during linguistic tasks that can elicit a large variety of responses. During these tasks, listeners produce different possible meanings and list all the other words that come to their minds. It is believed that the right hemisphere of the brain commands divergent semantic processing through its coarse grained, large windows of temporal integration. Neurons in the right hemisphere occupy overlapping regions of space, allowing for the network activation of concepts necessary for divergent processing.Neurons in the right hemisphere
The right hemisphere activates concepts that are more loosely associated with a stimulus, allowing for production of non-literal and less frequent meanings of words. Activation of words in the Right Hemisphere is less discriminant compared to the Left Hemisphere. It will activate closely related words to the same extend as the loosely related words. Though the Right Hemisphere is slower in activating the dominant and subordinate meanings of ambiguous words, the activation of both dominant and subordinate meanings are sustained for longer periods of time compared to the Left Hemisphere's activation during convergent semantic processing. Studies of patient with right hemisphere damage have demonstrated a disruption of divergent semantic processing, causing subjects to affiliate words with concrete, literal meanings produced by the left hemisphere. They are able to understand the primary meanings of individual words, and also don't have impairments at the phonemic level. For example, a subject with right hemisphere damage will group the word “deep” with its antonym “shallow,” and have trouble producing the non-literal association of “deep” with “wise.” Furthermore, their significant loss of divergent processing can affect things like their ability to understand jokes, metaphors, idioms, etc., as proper understanding may be heavily reliant on sustained activation of the different meanings of a word. Other right hemisphere deficits include naming categories but not functions, naming pictures of collective nouns, and naming goal-oriented categories.Examples of divergent processing
To test for divergent processing, the experimenter would instruct the subject to produce as many verbs as possible for a stimulus. For example, if the stimulus was basketball, the subject would list to shoot, to pass, etc. Further examples are below ;Stimulus/Verbs * Basketball: To shoot, to pass, to throw, to dribble, to steal, to block, to tip, to spin, etc. * Pencil: To write, to draw, to erase, to break, to sharpen, to scribble, to flick, etc. * Phone: to call, to text, to scroll, to play, to communicate, to connect, etc.Example of hemispheric differences in associations
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