Hypnosis and Memory

In TV shows or movies, there are scenes in which people are given a suggestion that they would not remember a certain thing (such as a person's name or an incident, either during the session itself (hypnotic amnesia) or at the end of hypnosis (posthypnotic amnesia). A reversal cue could also be given, a phrase such as "You will now remember everything"; once the person hears this, their state of amnesia ends.

According to research, around 25% of hypnotised college students could be led to experience amnesia. Although researchers agree that hypnotic and posthypnotic amnesia occur, they do still debate the causes. Some feel that it's a result of voluntary attempts in avoidance of thought on certain information, while others believe it to be caused by an altered state of conscientiousness which weakens normal memory systems.

Memory Enhancement

In contrast to producing the effect of forgetting, can hypnosis enhance memory?

Law enforcement agencies sometimes use hypnosis in aid of eyewitnesses to a crime. In a famous case in California which occurred in 1977, a bus carrying 26 children and its driver disappeared without a trace. The victims, buried underground in an abandoned trailer truck by three kidnappers, were later found alive. After the rescue, an expert hypnotised the bus driver and asked him to recall the ordeal. The driver formed a vivid image of the kidnappers' white van and could "read" all but one digit of the vans licence plate. The information helped track down the kidnappers.

Despite occasional success stories such as this, controlled experiments find that hypnosis is unable to improve memory. In some experiments, participants watch videotapes of simulated bank robberies or other crimes. Next, while hypnotised or not, they are questioned by police investigators or criminal lawyers. Hypnotised individuals tend to remember better than non-hypnotised individuals in some studies, but not all. There have been experiments where hypnotised participants had performed much poorly than non-hypnotised people; they had recalled more information, but much of it was inaccurate.

Another concern regarding this is that some memories recalled under hypnosis maybe pseudomemories—false memories created during hypnosis by statements or leading suggestions made by the examiner. In some experiments, hypnotised and non-hypnotised participants are intentionally exposed to false information about an event (e.g.: about a bank robbery). Later, once the hypnotised subjects are brought out of their hypnosis, they are questioned. Highly suggestible individuals that have been hypnotised are the ones most likely to report the false information as being a true memory and often tend to be confident of the accuracy of their memories.

Although some psychologists are exploring ways to minimise hypnosis-induced memory errors, at present, many courts have banned or limited testimonies obtained under the influence of hypnosis. The increased suggestibility of hypnotised individuals makes them particularly susceptible to memory distortion caused by leading questions, and they may come to believe things that never occurred in the first place. Similarly, if a therapist uses hypnosis to help patients recall long-forgotten memories of sexual abuse, what shall we conclude? Are the memories real, or are they pseudomemories created during therapy sessions?

Disassociation

What is hypnosis ad how does it produce its effects?

Several researchers propose theories that view hypnosis as an altered state involving a disassociation of consciousness. Ernest Hilgard proposed that hypnosis creates a division of awareness in which the person simultaneously experiences two streams of consciousness that are cut off from each another. One stream responds to hypnotic suggestions, while the other—the part of consciousness which monitors behaviour—remains in the background, but is aware of everything that goes on. Hilgard reefers to this second part of consciousness as the Hidden Observer.

Suppose a hypnotised subject is given a suggestion that she wouldn't feel pain. Her arm is lowered into a tub of ice-cold water for 45 seconds and every few minutes, she reports the amount of pain. In contrast to unhypnotised subjects, who find this experience moderately painful, she would probably report feeling less pain. But suppose the procedure is done differently. Before lowering the subject's arm, the hypnotist says, "Perhaps there is another part of you that is more aware than your hypnotised part. If so, would that part of you report the amount of pain."

In this case, the subject's other stream of consciousness, the Hidden Observer, would report a higher level of pain.

For Hilgard, this disassociation explained the reason behind the involuntary automatic behaviour that occurs under hypnosis. Given the suggestion "Your arm will start to feel lighter and will begin to rise," the subject intentionally raises his or her arm, but only the Hidden Observer is aware of this. The mainstream of consciousness that responds to the command is blocked from this awareness and perceives that the arm is rising all by itself.

Dementia & Alzheimer's Disease

Dementia is a reference to impaired memory and other cognitive deficits that accompany brain degeneration, as well as interference with normal functioning. There are more than a dozen types and causes of dementia.

Dementia is more prevalent among the elderly. However, it can occur at any point in life. In dementia, cognitive abilities are gradually lost, accompanied by brain degeneration. In people with dementia, there is an occurrence of abnormal progressive degeneration of brain tissue as a result of disease or injury.

Dementia is most common in late adulthood. The term Senile Dementia refers to dementia that begins after the age of 65. Alzheimer's Disease is the most common cause of senile dementia, but Parkinson’s Disease, Huntington Disease and Creutzfeldt-Jakob Disease are other common causes. Complications from high blood pressure and strokes may also cause it.

Scientific Studies

A large Canadian study has found an overall rate of senile dementia of around 8 percent, as well as a female-to-male ratio of about 2:1. Whereas 2 percent of 65- to 74-year-olds are estimated to have dementia, there is an increase in rate to 11 for 75- to 84-year-olds, as well as 34 percent for people who are 85 and above.

Impaired memory, in particular, for very recent events, is typically one of the first symptoms of dementia. Poor judgement, language problems and disorientation may appear gradually or sporadically, and people who develop dementia typically have distress episodes due to confusion. Their behaviour may become uninhibited, they may lose the ability to perform familiar tasks, and they may experience a significant physical decline in addition to cognitive impairments.

Comparing with adults aged 65 and older, those who are more frequently engaged in activities that stimulate cognitive functioning show a lower risk of subsequently developing Alzheimer's disease; but whether this truly reflects a causal relationship remains to be seen. However, one thing is certain: as people live longer lives, the need to find a cure for Alzheimer’s disease and other forms of senile dementia becomes a matter of urgency. Until then, many of us can expect our family members to become Alzheimer’s patients.

Caregiving

Being a caregiver for a spouse or elderly parent with dementia can, unfortunately, be a stressful and psychologically painful experience. Over half of the patients diagnosed with senile dementia show a combination of depression, anxiety, agitation, paranoid reactions, as well as disordered thinking, which may resemble schizophrenia. Ultimately, it could result in the inability to walk, talk, or recognise family members or close friends.

In-depth studies done in Finland, the United States, and Germany, have found that among adults above the age of 65 not suffering from dementia, 20 to 25 percent do have mild cognitive impairment. Combining cases of mild impairment and dementia, some experts have estimated that 79 percent of 65- to 74-year-olds; and 45 percent of people aged 85 and older, remain cognitively normal.

Though these are not pleasant statistics, they make it clear that even well into old age, cognitive impairment isn’t inevitable; and that even with the decrease of some mental abilities with age, more knowledge and wisdom could still be accumulated.        

Alzheimer's Disease (AD)

Alzheimer's disease is a progressive brain disorder which is the most common cause of dementia among adults over the age of 65, according to around 50 to 60 percent of such cases. An overall of 2 to 4 percent of the elderly is estimated to have AD.

The early symptoms AD, which worsen gradually over a period of years, include forgetfulness, poor judgement, confusion, and disorientation. Often, memory of recent events and new information is especially impaired. Forgetfulness by itself is not necessarily a sign of a person developing AD; however, memory happens to be the first psychological function that is affected, as AD initially attacks the subcortical temporal lobe regions—areas near the hippocampus, as well as the hippocampus itself—that help in the conversion of short-term memory into long-term memory.

Alzheimer's disease spreads across a person’s temporal lobes and then to the frontal lobes, as well as to other cortical regions. According to a German physician Alois Alzheimer, who first noticed the disease a century ago, patients afflicted with this disease have an abnormal amount of plaques and tangles in their brains. Plaques happen to be clumps of protein fragments which happen to build up on the outside of the neurons, whereas tangles are fibres that get twisted and wound up together within the neurons.

Neurotransmitter Systems

Neurons tend to become damaged and die, brain tissues shrink, and communication between the neurons is impaired as AD disrupts several neurotransmitter systems, especially the acetylcholine system. Acetylcholine plays a key role in synaptic transmission in several brain areas involved in memory, and drugs that help maintain acetylcholine functioning have had some temporary success in improving cognitive functioning in AD patients.

As AD progresses, working memory and long-term memory worsen. For example, if you read a list of just three words to a healthy 80-year-old and test his recall after a brief time delay, they tend to typically remember at least 2 words if not all three. On the other hand, a patient with AD will recall 1 or none.

Anterograde and retrograde amnesia become more severe and procedural, semantic, episodic, and prospective memory can all be affected. Patients may lose the ability to learn new tasks or remembering new information or experiences, as well as forget how to perform familiar tasks and have trouble recognising even close family members.

Genetic Causes

What causes AD and its characteristic plaques and tangles? According to scientific identification, several genes contribute to early-onset AD; an inherited form of the disease which develops before the age of 65 and as early as 30, but only accounts to about 5 to 10 percent of AD cases.

However, the precise cause of the more typical, late-onset AD remains elusive; but researchers have identified one genetic risk factor. This gene helps direct the production of proteins which carry cholesterol in the blood plasma, and high cholesterol and other risk factors for cardiovascular disease may likewise increase the risk of developing AD. A recent study found that even healthy elderly adults who carried this particular gene, as compared to peers that did not, performed more poorly on prospective memory tasks.

If you know anyone with AD, you are aware that it involves much more than memory loss. These patients experience language issues, disorganised thinking, and changes in mood as well as personality. Ultimately, they may lose the ability to speak and walk, and may also lose control over bladder and bowel functioning.

The Decay of Memory

Decay Theory

Information in sensory memory and short-term memory decays quickly with time, but does long term memory decay as well? An early explanation for forgetting was Decay Theory, which proposed that as time passed and being disused, long-term physical memory traces in the nervous system can fade away. But Decay Theory soon fell into disfavour as scientists were unable to locate neither physical memory traces nor measure physical decay.

However, of recent decades, scientists have begun unravelling the manner in which neural circuits change with the formation of a long-term memory formation, sparking new interests in examining the way these changes might decay over time.

Unfortunately, Decay Theory’s prediction of; the longer the time interval of disuse between learning and recall, the less should be recalled; is problematic. For example, some professional actors tend to display perfect memory for words last used by them on stage two years ago despite having moved on to new acting roles and scripts.

Moreover, when research participants learn a list of words or a set of visual patterns and are retested at two different times, they, at times, recall material during the second resting that they were unable to remember during the first. This phenomenon, called Reminiscence, seems inconsistent with the concept that a memory trace decays over time. To sum up, scientists still debate the validity of Decay Theory.

Motivted Forgetting

Psychologists propose that people, at times, are consciously or unconsciously motivated to forget. According to Sigmund Freud, it was often observed that during therapy sessions, his patients remembered long-forgotten traumatic or anxiety-arousing events. For example, one of his patients suddenly remembered with great shame such an event in which she, while standing beside her sister's coffin, thought: "Now my brother-in-law is free to marry me."

Freud's conclusion was that the thought was so shocking and anxiety-arousing that the woman had repressed it and pushed it down into her unconscious mind, and left it there to remain until it was later uncovered during a therapy session. Repression is a motivational process which protects us by blocking the conscious recall of anxiety-arousing memories.

The concept of repression is controversial, with some evidence supporting it while others disreputing it. People do tend to forget unpleasant events—even traumatic events—yet they can forget very pleasant ones as well. If a person can't recall a negative experience, is it due to repression or to normal information processing failures? Overall, it has been difficult to demonstrate experimentally that a special process akin to repression is the cause of memory loss in the case of anxiety-arousing events.

Prospective Memory

Have you ever forgotten things like mailing a letter, turning off your oven, purchasing a thing you need from the market, or keeping an appointment? In contrast to Retrospective Memory, which is a reference to events of the past, Prospective Memory concerns remembering to perform an activity in the future. That individuals forget to do things as often as they do is interesting, because prospective memory typically involves little content.

Often we need only to recall that we must perform an event-based task ("Remember to mail the letter on your way home" or "Remember to buy milk when you are at the supermarket") or a time-based tasks ("Remember to take your medication at 5:00 pm" or "Remember to keep your doctors appointment at 2:00 pm").

Successful prospective memory, however, draws on cognitive abilities such as planning and allocation of attention while performing other tasks.

During adulthood, do we become increasingly absentminded about remembering to do things, as suggested by a common stereotype? Numerous laboratory experiments support this view. Typically, participants are asked to perform a task requiring their ongoing attention while trying to remember to signal the experimenter at certain time intervals or whenever specific events take place.

Older adults, in general, tend to display poorer prospective memory, especially when the signalling is time-based. However, when prospective memory is tested outside the laboratory using tasks such as simulated pill-taking, healthy adults in their 60s to 80s often perform as well as—or even better than—adults in their 20s. Perhaps older adults feel more motivated to remember in such situations, or maybe they rely more on habit and on setting up of a standard routine.

Amnesia

As  H.M.'s case illustrates, the most dramatic instances of forgetting occur in amnesia. The term Amnesia is commonly referred to as memory loss due to special circumstances such as brain injury, illness, or psychological trauma. However, as we'll see shortly, there is one type of amnesia experienced by everyone.

Amnesia takes several forms: Retrograde Amnesia represents memory loss for events that took place sometime before the onset of amnesia. For example, H.M.'s brain operation, which took place at age 27, caused him to experience mild memory loss for events in life that had occurred during the preceding year or two. For example, when he was 25 to 26 years old.

Football players experience retrograde amnesia when they are knocked out by a concussion; they regain consciousness and cannot remember the events that had occurred just before being hit.

Anteretrogade Amnesia refers to memory loss for events that occur after the initial onset of amnesia. H.M.'s brain operation and, pratricularly the removal of much of his hippocampus, produced severe anterograde amnesia, robbing him of the ability to consciously remember new experiences and facts.

Similarly, the woman whose hand was pinpricked by Swiss psychologist Edouard Claparède during a handshake also suffered from anterograde amnesia; moments later, she could not consciously remember the episode. But, unlike HM's anterograde amnesia, hers was caused by Korsakoff's Syndrome, which can result from chronic alcoholism. It may also cause retrograde amnesia.