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Posts Tagged ‘perception’

Memories May Skew Visual Perception

December 16, 2012 3 comments

Taking a trip down memory lane while you are driving could land you in a roadside ditch, new research indicates.

Vanderbilt University psychologists have found that our visual perception can be contaminated by memories of what we have recently seen, impairing our ability to properly understand and act on what we are currently seeing.

“This study shows that holding the memory of a visual event in our mind for a short period of time can ‘contaminate’ visual perception during the time that we’re remembering,” Randolph Blake, study co-author and Centennial Professor of Psychology, said.

“Our study represents the first conclusive evidence for such contamination, and the results strongly suggest that remembering and perceiving engage at least some of the same brain areas.” Read more…

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Researchers Explore How the Brain Perceives Direction and Location

December 16, 2012 Leave a comment

The Who asked “who are you?” but Dartmouth neurobiologist Jeffrey Taube asks “where are you?” and “where are you going?” Taube is not asking philosophical or theological questions. Rather, he is investigating nerve cells in the brain that function in establishing one’s location and direction.

Taube, a professor in the Department of Psychological and Brain Sciences, is using microelectrodes to record the activity of cells in a rat’s brain that make possible spatial navigation—how the rat gets from one place to another—from “here” to “there.” But before embarking to go “there,” you must first define “here.”

Survival Value

“Knowing what direction you are facing, where you are, and how to navigate are really fundamental to your survival,” says Taube. “For any animal that is preyed upon, you’d better know where your hole in the ground is and how you are going to get there quickly. And you also need to know direction and location to find food resources, water resources, and the like.”

Not only is this information fundamental to your survival, but knowing your spatial orientation at a given moment is important in other ways, as well. Taube points out that it is a sense or skill that you tend to take for granted, which you subconsciously keep track of. “It only comes to your attention when something goes wrong, like when you look for your car at the end of the day and you can’t find it in the parking lot,” says Taube. Read more…

Right And Left Brain

February 17, 2012 1 comment

The brain is divided physically into a left and right half is not a new discovery. The Egyptians knew that the left side of the brain controlled and received sensations from the right side of the body and vice versa.

It is only in the last two dozen years, however, that the true implication of the left/right split has gradually become apparent, through the work of a number of researchers. The most famous are probably Dr.  Roger Sperry and Dr. Robert Ornstein of the California Institute of Technology. Their work has won them a Nobel prize.

Sperry and Ornstein noted that the left and the rig hemispheres are connected by an incredibly complex  network of up to 300 million nerve fibres called the Corpus callosum. They were also able to show that the two halves of the brain tend to have different functions.

They (and other researchers) indicate that the left brain primarily appears to deal with language and mathematical processes and logical thought, sequences, analysis and what we generally label academic  pursuits. The right brain principally deals with music, and visual impressions, pictures, spatial patterns, and colour recognition. They also ascribe to the right brain the ability to deal with certain kinds of conceptual   thought – intangible ‘ideas’ such as love, loyalty, beauty.

The specialization of the two halves of the brain can result in some bizarre behaviour. Patients who, for medical reasons, have had their Corpus callosum  severed,  have effectively two semi-independent brains: two minds in one head.

If a ball is shown to the left visual field of such a person, i.e. registered to their right brain hemisphere, the speaking half of the brain, which is in the other, (left) brain will claim to have seen nothing. If, however, the patient is asked to feel in a bag of assorted shapes he will correctly pull out a ball. If he is asked what he has done he will say ‘nothing’. The ball has only been seen with the right brain, and felt with the right brain. The speech centre, which is located in the left brain, has registered nothing.

Even more delicate experiments have been performed on surgically split-brained patients. The word SINBAD was projected to such a patient while his eyes were focused on the precise spot between N and B. The first 3 letters went to his right brain, the last three to his left hemisphere. When asked to saywhat he had seen, he replied BAD. When asked to point with his left hand to what he had seen he pointed to the word SIN.

The specialisation of the two brains  has also been demonstrated by measuring the electrical activity of the brain during various activities.

When the brain is relaxed in a state of rest, it tends predominantly to show an alpha brain wave rhythm – i.e. 8-12 Hz waves. Ornstein found that a subject tackling a mathematical problem showed an increase in alpha in the right hemisphere. This indicated that the right side was relaxing whilst the left was active and, therefore, in a beta brain wave pattern. In contrast, when a subject was matching coloured patterns, the left showed alpha (i.e. was resting) and the right showed beta (i.e. was active). More on brain waves can be found here.

The brain scans, show the varying levels of electrical brain activity in a subject listening to music, words and singing. The first activity (music) involved the right brain. The second (listening to words only) involved the  left brain, but singing (words and music together) involved the whole brain.

The left brain is now thought to be the half that specialises in serial, sequential thought, i.e. analysing  information in sequence in a ”logical” step by step approach. The left rationalises. The right brain seems to take in several bits of information ”at a glance” and process them into one overall thought. The right synthesises.

To read more click on this link to the full article: Right and Left Brain