Verbal intelligence

Verbal intelligence is the ability to understand and reason using concepts framed in words. More broadly, it is linked to problem solving, abstract reasoning, and working memory. Verbal intelligence is one of the most g-loaded abilities.

In order to understand linguistic intelligence, it is important to understand the mechanisms that control speech and language. These mechanisms can be broken down into four major groups: speech generation (talking), speech comprehension (hearing), writing generation (writing), and writing comprehension (reading).

In a practical sense, linguistic intelligence is the extent to which an individual can use language, both written and verbal, to achieve goals.

Linguistic intelligence is a part of Howard Gardner's multiple intelligence theory that deals with individuals' ability to understand both spoken and written language, as well as their ability to speak and write themselves.

Speech production is the process by which a thought in the brain is converted into an understandable auditory form. This is a multistage mechanism that involves many different areas of the brain. The first stage is planning, where the brain constructs words and sentences that turn the thought into an understandable form. This occurs primarily in the inferior frontal cortex, specifically in an area known as Broca's area. Next, the brain must plan how to physically create the sounds necessary for speech by linking the planned speech with known sounds, or phonemes. While the location of these associations is not known, it is known that the supplementary motor area plays a key role in this step. Finally, the brain must signal for the words to actually be spoken. This is carried out by the premotor cortex and the motor cortex.

In most cases, speech production is controlled by the left hemisphere. In a series of studies, Wilder Penfield, among others, probed the brains of both right-handed (generally left-hemisphere dominant) and left-handed (generally right-hemisphere dominant) patients. They discovered that, regardless of handedness, the left hemisphere was almost always the speech controlling side. However, it has been discovered that in cases of neural stress (hemorrhage, stroke, etc.) the right hemisphere has the ability to take control of speech functions.

Verbal Comprehension is a fairly complex process, and it is not fully understood. From various studies and experiments, it has been found that the superior temporal sulcus activates when hearing human speech, and that speech processing seems to occur within Wernicke's area.

Hearing plays an important part in both speech generation and comprehension. When speaking, the person can hear their speech, and the brain uses what it hears as a feedback mechanism to fix speech errors. If a single feedback correction occurs multiple times, the brain will begin to incorporate the correction to all future speech, making it a feed forward mechanism. This is apparent in some deaf people. Deafness, as well as other, smaller deficiencies in hearing, can greatly affect one's ability to comprehend spoken language, as well as to speak it. However, if the person loses hearing ability later in life, most can still maintain a normal level of verbal intelligence. This is thought to be because of the brain's feed forward mechanism still helping to fix speech errors, even in the absence of auditory feedback.