Imagery- Verbal vs Visual Imagery

mental imagery broadly as the processing of perceptual-like information in the absence of an external source for the perceptual information.

Verbal Imagery Vs Visual Imagery
Cognitive neuroscience has provided increasing evidence that several dif- ferent brain regions are involved in mental imagery. This evidence has come from both studies of patients suffering damage to various brain regions and studies of the brain activation of normal individuals as they engage in vari- ous imagery tasks. In one of the early studies of brain activation patterns during mental imagery, Roland and Friberg (1985) identified many of the brain regions that have been investigated in subsequent research. The inves- tigators measured changes in blood flow in the brain as participants either mentally rehearsed a nine-word circular jingle or mentally rehearsed finding their way around streets in their neighborhoods.  When participants engaged in the verbal jin- gle task, there was activation in the prefrontal cortex near Broca’s area and in the parietal-temporal region of the posterior cortex near Wernicke’s area. Patients with damage to these regions show deficits in language processing. When participants engaged in the visual task, there was activation in the parietal cortex, occipital cortex, and temporal cortex. All these areas are involved in visual perception and attention. Thus, when people process imagery of language or visual information, some of the same brain areas are active as when they process ac- tual speech or visual information.
An experiment by Santa (1977) demonstrated the functional consequence of representing information in a visual image versus representing it in a verbal image. The two conditions of Santa’s experiment. In the geometric condition, participants studied an array of three geometric objects, arranged with one object centered below the other two. As can be seen without much effort, this array has a facelike property (eyes and a mouth). After participants studied the array, it was removed, and they had to hold the information in their minds. They were presented with one of sev- eral different test arrays. The participants’ task was to verify that the test array contained the same elements as the study array, although not necessarily in the same spatial configuration. Thus, participants should have responded posi- tively to the first two test arrays and negatively to the last two. The interesting results concern the difference between the two positive test ar- rays. The first was identical to the study array (same-configuration condition). In the second array, the elements were displayed in a line (linear-configuration condition). Santa predicted that participants would make a positive identifi- cation more quickly in the first case, where the configuration was identical— because, he hypothesized, the mental image for the study stimulus would preserve spatial infor- mation. The results for the geometric condition. Par- ticipants were faster in their judgments when the geometric test array preserved the configuration information in the study array.
The results from the geometric condition are more impressive when contrasted with the results from the verbal condition. Here, participants studied words ar- ranged exactly as the objects in the geometric condition were arranged. Because it involved words, however, the study stimulus did not sug- gest a face or have any pictorial properties. Santa speculated that participants would read the array left to right and top to bot- tom and encode a verbal image with the information. So, given the study ar- ray, participants would encode it as “triangle, circle, square.” After they stud- ied the initial array, one of the test arrays was presented and participants had to judge whether the words were identical. All the test stimuli involved words, but otherwise they presented the same possibilities as the test stimuli in the geometric condition. The two positive stimuli exemplify the same-configura- tion condition and the linear-configuration condition. Note that the order of words in the linear array was the same as it was in the study stimulus. Santa predicted that, unlike the geometric condition, because participants had en- coded the words into a linearly ordered verbal image, they would be fastest when the test array was linear. His predictions were again confirmed.
■ Different parts of the brain are involved in verbal and visual imagery, and they represent and process information differently.