The Visuospatial Sketchpad, what is it?
The Visuo-spatial sketchpad (VSS) is an important element in the function of working memory, as it is responsible for storing and processing information in visual or spatial form, as well as the location or speed of objects in space.
Components
It has been proposed that the VSS can be further subdivided into 2 separate visual and spatial components: the visual cache – stores information on form and colour, and the inner scribe – focuses on spatial and movement information. The inner scribe also rehearses information in the visual cache and transfers information to the central executive.
Function
The Visuo-spatial sketchpad is used in ways such as: temporarily storing information on how things look, for example, shapes and colours, and is also what allows us to manipulate images in our mind. This can be seen in a game of Tetris, as one rotates a shape to see how it might fit or appear from a different angle.
In addition, the VSS is also used for tasks such as navigation – when we need to give directions to a friend or simply navigate ourselves through the city.
Another function of the VSS is recreating images either based on something we’re seeing currently in real time or something we’ve seen in the past. For example, drawing a flower. You use your VSS to hold onto a picture of a flower in your mind while trying to reproduce it onto paper. However, an interesting note is that images from our VSS fade quickly. While creating a drawing of the flower, one must either keep referring back to the actual flower or continue to retrieve an image of a flower from your Long-term Memory.
Cravings and the VSS
Prior literature by Cornell, Rodin, and Weingarten in 1989 gives evidence that hunger is not a necessary component for the occurrence of a food craving. In their research they found that participants reported cravings for both pizza and ice cream upon being displayed both of these foods, regardless of whether they were hungry or full. This led to the premise that there is an imagery basis to food cravings.
In more recent research by Kemps, Tiggeman, and Wood in 2005 applied this premise and demonstrated that loading the visuo-spatial sketchpad with a task such as dynamic visual noise, all the while imaging popular or commonly craved foods (ex. Chocolate cake) actually reduced the vividness of the participants’ food images and similarly, so reduced their level of craving.
Purpose:
This study laid the groundwork and was used as a launch pad in Steel, Kemps, and Tiggeman research in 2005, which looked at the effects of hunger as well as visuo-spatial interference on imagery-induced food cravings. The purpose was to investigate the manner in which hunger and visuo-spatial interference might affect imagery-induced food cravings
Methods:
The study included 42 first year females, ranging from ages 18-33, who were randomly assigned to either a “hungry” or “not-hungry” condition. The hungry condition was asked to refrain from eating and drinking anything except water for four hours prior to the testing session, whereas the not-hungry condition was asked to eat immediately prior to the session.
The participants were asked to name their top three foods they were craving “right now,” which in turn was used as stimuli in the imagery task. This was a key change from previous literature, as prior to this, the craved foods that were used as stimuli were experimenter chosen. The most commonly reported foods that participants were craving were pasta, chocolate, and ice cream.
The participants were then asked to form an image of one of their foods they nominated as “most craved” and hold the image for 5 seconds.
Then, participants were asked to do one of two tasks depending on whether they were in the control or experimental condition. The control condition was asked to maintain the image of their craved food for a further 8 seconds while focusing on a blank computer screen. Meanwhile, the experimental condition was asked to focus on a computer screen that displayed a matrix of black and white squares. The squares changed from black and white, or white to black resulting in a “flickering” effect, also known as “dynamic visual noise.” Finally, the participants were asked to rate vividness of their image and their craving intensity.
Results
In regards to imagery vividness, it was found that imagery vividness in the dynamic visual noise condition decreased, and there showed greater decrease in the hungry than in the not hungry condition. There was no difference in the control condition, regardless of hunger status.
In regards to craving intensity, participants in the hungry group reported more intense cravings than those in the not-hungry group. Of most interest, is that the craving intensity was lower for the dynamic visual noise condition than the control condition.
In other words: higher ratings of imagery vividness are associated with higher ratings of craving intensity. So the better one is able to picture the food, without having to focus on other visual stimuli, the stronger the craving.
Significance
The idea behind the study was to investigate if performing two concurrent VSS tasks would differentially affect cravings that arise from hunger and those that are not from hunger.
And indeed it was found that performing simultaneous tasks that both load the VSS not only reduced the vividness of the image of the food, but as well as the craving. This reduction comes about because these two visual tasks are competing for an already limited capacity in the visual-spatial working resource. In other words because of the added load on the VSS, the information in storage cannot be effectively retained because the two tasks are competing for the same processing resource. Therefore, there is a reduction in processing efficiency.
This comes back to the main finding of the study – the decrease in imagery vividness occurred regardless of whether the craving was as a result of hunger or for other reasons.
So what?
The findings of this research are relevant in that they can assist those who have a medical condition which requires them to be on a particular or strict diet, for example, type II diabetes.
Since dynamic visual noise was shown to work equally well for cravings triggered by factors other than physiological needs and hunger, it can assist with cravings from negative mood states and environmental cues that have been associated with eating disorders. Simple VSS techniques may help alleviate hunger-driven cravings or the intensity of psychologically induced cravings, or whomever finds them a serious problem.
Working Memory 