Attention has been a much-discussed topic in psychology for years. This article will focus on visual attention, specifically voluntary visual attention. Two important, much-discussed theories will be discussed and it will end with a brief description of the parts of the brain involved in visual attention.
Voluntary visual attention
Visual attention allows people to select information that is important to them and the behavior they perform (Munneke, 2008). Visual attention can be covert and overt . Covert visual attention means that the eyes do not move. During overt visual attention, the eyes do move (Moore, 2006).
Voluntary visual attention is also called endogenous attention . This means that attention is directed from within. People want to look at something and they look at this.
Recent research has shown that voluntary attention involves top-down mechanisms (Moore, 2006). This means that signals are sent from the brain to the rest of the body. This is in contrast to bottom-up, where the brain receives signals. This is involved in involuntary attention mechanisms. This is the case, for example, if your eyes are drawn to something without you doing this on your own. Involuntary attention will not be discussed here.
The Premotor Theory of Attention
The premotor theory of attention states that there is a similar mechanism for programming eye saccades (eye movements) and spatial attention (Moore, 2006). There is a lot of disagreement about this theory. Rizzolatti and his colleagues (1987), among others, provided evidence for this theory. Several experiments had shown that an observer is faster and more accurate when a stimulus appears where one expects it than when it appears at an unexpected location. They also conducted an experiment to find out why this reaction is faster. They conducted this experiment with 8 men, all students at the same university, all right-handed and all could see normally. They had to focus on a fixation point and a stimulus appeared at one of 12 possible points around this point. In some trials, certain points were cued, meaning that the stimulus was more likely to appear there. In other trials, nothing was cued. The reaction times were measured and compared. The conclusion was that responses were indeed faster to stimuli that appeared at expected points (Rizzolatti, 1987). This is evidence for the premotor theory because the cues already programmed the saccade, as it were, and then the stimulus appeared. If the stimulus appears somewhere else and one still executes the programmed saccade, the reaction time is longer because one still has to look for the stimulus.
Hoffman and Subramaniam (1995) also found that stimuli were more easily detected if the stimuli appeared in a location where the subjects wanted to move their eyes. Saccades made to an attention-grabbing stimulus also have higher accuracy (Kowler, 1995).
The searchlight theory of attention
Another theory of visual attention is the searchlight theory of attention . The searchlight theory of attention compares attention to a searchlight. This theory was formulated by Posner and states that attention slides through the perceptual field like a searchlight, and thus attention is focused on things (Munneke, 2008). If this theory is accepted as true, there are two possible consequences. The first possible consequence is that attention moves through the field at an equal speed. The second possible consequence is that attention moves in equal time regardless of location. If we assume a constant speed, the reaction time to a stimulus should become slower as the stimulus is further from a fixation point. If, on the other hand, we assume that the time with which one responds is the same, we will not find such a relationship between distance and response (Rizolatti, 1987). Attention has been found to influence the speed at which we move our eyes horizontally and vertically. If one knows where one wants or needs to direct one’s attention, for example through instructions from an experimenter, the speed is greater (Kohler, 2008)
Activation in the primary visual cortex
What actually happens in the brain when we focus our visual attention on something? fMRI research has made it possible to map this in detail. Much research has been done in these areas, for example by Munneke and his colleagues (2008). As a result, they also found that subjects responded faster when the locations were cued than to stimuli at uncued locations. Munneke and his colleagues also conducted fMRI research to see how the brain responded and which parts of the brain had the most activity. They found evidence for Posner’s searchlight theory and that directing the spotlight causes activity in all visual areas of the brain. They also investigated how the brain responded to stimuli in the same or opposite hemisphere where a cue had appeared. There was a certain amount of time between the cue and the stimuli, varying in length. They found an effect where activation in the brain was higher when cue and stimulus appeared in the same hemisphere, the peak of activation was between 6-8 seconds each time. This peak was also visible when there were 6 to 8 seconds between the cue and the stimulus in different hemispheres, but this peak was lower, and therefore the activation was also lower, than in the same hemisphere (Munneke, 2008).
Conclusion
There are many different theories regarding attention and how we focus our attention on things around us. There is also evidence for many of these theories. fMRI has made it possible to map exactly which parts of the brain are involved in visual attention, and to what extent.