Integration with Other Modalities

Vision is not an encapsulated system. It interacts with and depends on other sensory modalities. For example, vision interacts with the vestibular system (which is responsible for balance and coordination) in the vestibulo-ocular reflex.

vestibulo-ocular reflex

The vestibulo-ocular reflex is responsible for the coordination of motion information (from the vestibular system, which knows about body motion and position) with visual information that allows you to maintain your gaze on an object while you move. For example, when you move your head in one direction, your eyes reflexively move in the opposite direction to compensate, allowing you to maintain your gaze on the object that you are looking at.

You can experience this compensation quite simply. First, while you keep your head still and your gaze looking straight ahead, wave your finger in front of you from side to side. Notice how the image of the finger appears blurry. Now, keep your finger steady and look at it while you move your head from side to side. Notice how your eyes reflexively move to compensate for the movement of your head and how the image of the finger stays sharp and stable.

Vision also interacts with your proprioceptive system, to help you find where all your body parts are, and with your auditory system, to help you understand the sounds people make when they speak. You can learn more about this in the multimodal module.

Finally, vision is also often implicated in a blending-of-sensations phenomenon known as synesthesia.

synesthesia

Synesthesia is the blending of two or more sensory experiences. It occurs when one sensory signal gives rise to two or more sensations.

The most common type is grapheme-color synesthesia. About 1 in 200 individuals experience a sensation of color associated with specific letters, numbers, or words: the number 1 might always be seen as red, the number 2 as orange, etc. But the more rare forms of synesthesia blend sensations from entirely different sensory modalities, like taste and color or music and color. For example, the taste of chicken might elicit a sensation of green, and the timbre of violin a deep purple.

Conclusion

All of this talk about vision may have you wondering what this has to do with psychology. Remember that sensation is input about the physical world obtained by our sensory receptors, and perception is the process by which the brain selects, organizes, and interprets these sensations. In other words, the senses are the physiological basis of perception. Perception of the same senses may vary from one person to another because each person’s brain interprets stimuli differently based on that individual’s learning, memory, emotions, and expectations. It is for this reason that psychologists study sensation—in order to understand perception, which is clearly a component of behavior and mental processes (the definition of psychology).