GLO 3: DISCUSS HOW AND WHY PARTICULAR RESEARCH METHODS ARE USED AT THE BIOLOGICAL LEVEL OF ANALYSIS. Ezequiel & Karina

Raine (brain scans)  The aim of this experiment was to discover if murderers who pleaded not guilty by reason of insanity(NGRI) show evidence of brain abnormalities.  PET scans were used to study the brains of 41 people who were charged with murder and pleaded not guilty for reaasons of insait, and compared them with 41 controls. All of the NGRI’s were referred to the imaging center to obtain evidence for the defense. Reasons for the referrals included schizophrenia head injuries, and personality disorders.  Participants were matched by age and sex to a control group of participants. All the participants were kept medication free for two weeks before the scanning. All participants were injected wit a glucose tracer and then given a PET scan. The NGRI’s were compared to the controls based on the level of activity( glucose metabolism) in the right and left hemispheres of the brain in 14 areas. The researchers looked at activity in 6 cortical areas( part of the cerebral cortex which is the outermost layer of nerve tissue of the cerebral hemispheres) and 8 Subcortical areas( brain structures below the cortex). In this study the results of the controlled participants were compared to the NGRI’s and the NGRI’s were found to have less activity in the prefrontal and parietal lobes and more activity in the occipital lobe

Raine (brain scans) continued  The results from the subcortical area found less activity in the corpus callosum. Another thing found was an imbalance of activity between the two hemispheres in three other subcortical structures. In the amygdala and the hippocampus, compared to the controls, the NGRI’s had less activity in the left side and more activity in the right side.  Raine argues that the difference in activity seen in the amygdala can be used to support theories of violence that suggest it is due to unusual emotional responses such as lack of fear.

Dement and Kleitman (sleep and dreaming) The aim of this experiment was to investigate the relationship between eye movements and dreaming. The study hade three hypotheses. One hypotheses was that there would be a significant association between REM sleep ( Rapid Eye Movement Sleep) and dreaming. The second was that there would be a significant positive correlation between the estimate of the duration of dreams and the lengths of eye movements. And the third hypotheses was that there would be a significant association between the pattern of eye movement and the context of the dream. There were 9 participants( 7 males and 2 females). Five were studied intensively, while only a small amount of data was collected on the others just to back up the findings of the five. The participants arrived at the lab around their usual bed time, they were asked to eat normally but to avoid caffeine and alcohol on the test day. They were then put to sleep in a dark room. An electroencephalograph(EEG) was used to record the signals of electrodes that were attached to participants face and scalp. Two of the electrodes were placed close to the participants eyes to record electrical changes caused by eye movement. At different times throughout the night the participants were awakened to test their dream recall. Results relating to Hypothesis 1 (There would be a significant association between REM sleep and dreaming).  REM sleep is mostly associated with dreaming, and N-REM Sleep ( Non- Rapid Eye Movement sleep) is associated with periods of non- dreaming sleep.  Nearly all dream recall in N-REM awakenings occurred within 8 minutes of an REM, suggesting that the dream might have been remembered from the previous REM.

Dement and Kleitman (sleep and dreaming) Continued Results relating to Hypothesis 2 (There will be a significant positive correlation between the estimate of the duration of dreams and the length of eye-movement).  The series of awakenings which were carried out to see if the participants could accurately estimate the length of their dreams revealed that all of the participants were able to accurately choose their dream duration. Results relating to Hypothesis 3 (There would be a significant association between the pattern of eye movement and the context of the dream).  There did appear to be some relationship between the dream content and the type of eye movements. For example, periods of vertical or horizontal eye movements were rare, but f a participant was woken up after a period of vertical eye movement they reported dreams such as: 1. climbing up a series of ladders looking up and down as he climbed. 2. Throwing basketballs at a net, first shooting and looking up at the net, and then looking down to pick a ball up off the floor  In the only instance of horizontal eye movements the dreamer was watching two people thro tomatoes at each other.

Sperry (split brains)  The aim of this experiment was to show that each hemisphere of the brain has different functions. The experiment involved eleven “ split-brain” patients( patients who had undergone disconnection of the cerebral hemispheres). Sperry used a number of tasks to investigate lateralism of brain function. One task that was used to send information to only one hemisphere of the brain involved asking the participants to respond to visual information, this involved putting a blindfold on one of the participanrts eyes and asking them to focus on a point on the middle of the screen using their other eye. The researcher would then put a stimulus on either side of the screen for 1/10 of a second to ensure that the participant would not have time for any eye movement as this would spread the information across both sides of the visual field and across both sides of the brain. Since language is processed in the left hemisphere of the brain, when a stimulus is present on the left side of the visual field of the patient they should not be able to name the stimulus. When patients were presented with an image in one half of the visual field and then presented with the same image on the other half of the visual field they would respond as if they had never seen the image before.