PsychScich07

advertisement
Gazzaniga • Heatherton • Halpern
Psychological Science
FOURTH EDITION
Chapter 7
Attention and Memory
©2013 W. W. Norton & Company, Inc.
“Coffee Break Brain”
Here’s a reason to tell your boss to “give you a break.” As this
ScienCentral News video explains, scientists working with rats
say breaks from activities may help your memory.
Attention and Memory
• In 1953, doctors took a radical surgical
approach to quiet the seizures of Henry
Molaison, aka H.M.
• Sadly and unexpectedly, the surgery caused
H.M. to lose the ability to remember things
over long periods of time
• Over the course of 40 years, H.M. participated
in countless experiments and became one of
the most famous people in memory research
7.1 What Is Memory?
• Describe the three phases of memory.
• Identify brain regions involved in learning and
memory.
• Describe the processes of consolidation and
reconsolidation.
Memory Is the Nervous System’s
Capacity to Acquire and Retain
Usable Skills and Knowledge
• Identity is made up of memories, including
recollections and knowledge of skills
• Memories are often incomplete, biased, and
distorted
– Can you think of an instance where you and a friend or
relative have had different memories of the same event?
• We have multiple memory systems, and each
memory system has its own “rules”
Memory Is the
Processing of Information
• The information processing model compares
the working of memory to the actions of a
computer
• Memory operates over time in three phases:
– encoding: the processing of information so that it
can be stored
– storage: the retention of encoded representations
over time
– retrieval: the act of recalling or remembering
stored information when it is needed
Memory Is the Result of Brain Activity
• Memory researchers have made tremendous
progress over the past two decades in
understanding what happens in the brain
when we acquire, store, and retrieve
memories
• What role does biology play in the processing
of information?
Memory’s Physical Locations
• Lashley’s term engram refers to the physical site of
memory storage; the place where memory “lives”
• Equipotentiality: the idea that memory is distributed
throughout the brain rather than confined to any
specific location
• In Hebb’s interpretation, memories are stored in
multiple regions of the brain, and they are linked
through memory circuits
• Multiple brain regions have been implicated in
memory, including the hippocampus, temporal lobes,
cerebellum, amygdala, and the brain structures
involved in perception
Consolidation of Memories
• Consolidation: a process by which immediate memories become
lasting (or long-term) memories
• The medial (middle) temporal lobes may be responsible for
coordinating and strengthening the connections among neurons when
something is learned and play an important role in the formation of
new memories
• Actual storage occurs in the particular brain regions engaged during
the perception, processing, and analysis of the material being learned,
e.g. sound is stored in the areas involved in auditory perception
• Remembering something seen or heard involves reactivating the
cortical circuits involved in the initial seeing or hearing
• Once the connections are strengthened sufficiently, the medial
temporal lobes become less important for memory
• Sleep may play an important role in the consolidation of memories
“Magnetic Brain Boost”
Whether we’re hitting the books for exams or in an extreme
situation like combat, we often lack sleep just when we need
to perform at our best. Now as this ScienCentral News video
reports, brain researchers studying how sleep deprivation
impairs memory have found a potential remedy.
Reconsolidation of Memories
• Nader and LeDoux proposed that once memories are
activated, they need to be consolidated again to be stored
back in memory
– reconsolidation: neural processes involved when memories are
recalled and then stored again for later retrieval, e.g. a librarian
returning a book to a shelf
• The reconsolidation process repeats itself each time a
memory is activated and placed back in storage, and it may
explain why our memories for events can change over time
• Using extinction during the period when memories are
susceptible to reconsolidation can be an effective method of
altering bad memories
– What drawbacks might there be from altering or losing memories?
“Your Memory Is Bigger and Better Than Scientists Expected”
Good news about our brains—turns out our visual memory is
bigger and better than previously thought. The study authors
even offer a tip to help improve your memory, and keep you
from losing your keys.
7.2 How Does Attention
Determine What We Remember?
• Distinguish between parallel processing and
serial processing.
• Describe filter theory.
• Define change blindness.
“Attention Training”
Just five days of special training improves young children’s
attention spans, and it makes the biggest difference for those
with attention deficits. As this ScienCentral News video explains,
it also improved one aspect of intelligence.
7.2 How Does Attention Determine
What We Remember?
• To get information into memory, a person needs to
attend.
• Attention is the ability to focus on certain stimuli;
this ability is adaptive in that it facilitates functioning
by enabling us to block out irrelevant information.
• Attention can be distracted by external sensory cues
or by internal thoughts and memories.
– In what situations are you easily distracted?
Our Visual Attention
Works Selectively and Serially
• Using visual search tasks, researchers like Anne Treisman have found that
we process basic features of stimuli (e.g., color, motion, orientation,
shape, and size) in parallel
– parallel processing: processing multiple types of information at the same time
• Parallel processing allows us to process information from different visual
features at the same time by focusing on targets instead of distractors
– targets:objects that differ from the others in only one feature
– distractors:other objects in the display
• Single-feature searches are fast and automatic and occur via parallel
processing
• Conjunction tasks are serial and effortful; they take longer and require
more attention because you need to process each stimulus individually
• Synesthetes may excel at visual search tasks because they may perceive
numbers in a particular color even if all the numbers are black
Our Auditory Attention
Allows Us to Listen Selectively
• Because attention is limited, it is hard to perform two tasks at
the same time, especially if the two tasks rely on the same
sensory or mental mechanisms
– How can talking on a cell phone affectdriving ability?
• Cherry’s cocktail party phenomenon highlights how a
particularly pertinent stimulus can capture your attention
• Cherry developed selective-listening studies to examine what
the mind does with unattended information when a person is
engaged in a separate task
– shadowing: in this procedure, the participant receives a different
auditory message in each ear. The participant is required to repeat, or
“shadow,” only one of the messages
What would happen if your own name were spoken into the
unattended ear?
Through Selective Attention,
We Filter Incoming Information
• Broadbent’s filter theory maintains that attention is
selective
• Stimuli that evoke emotions may readily capture
attention because they provide important
information about potential threats
• Socially relevant information, like a face, also
captures attention
• To some extent, however, we process information
contained in sensory stimuli to which we are not
consciously attending
Through Selective Attention We Filter
Incoming Information
• Because we cannot attend to everything in the
vast array of visual information available,
often we are “blind” to large changes in our
environments
– change blindness: a failure to notice large changes
in one’s environment
• Change blindness illustrates that our
perceptions can be inaccurate
Critical Thinking Skill:
Recognizing When “Change Blindness
Blindness” May Be Occurring
• Change blindness blindness is our unawareness that
we often do not notice apparently obvious changes
in our environments
• Attention influences memory
– How might your perception of a car accident as an
eyewitness differ from the driver’s?
– What factors may have distracted you from witnessing
critical moments of the incident?
• Recognizing the limitations of attention may help
prevent us from misleading ourselves about our
perceptions
“Time Flies”
Scientists have discovered why time flies. As this ScienCentral
News video reports, researchers have found it’s all about
grabbing your attention.
7.3 How Are Memories
Obtained Over Time?
• Distinguish between sensory memory, shortterm memory, and long-term memory.
• Describe working memory and chunking.
• Review evidence that supports the distinction
between working memory and long-term
memory.
• Explain how information is transferred from
working memory to long-term memory.
7.3 How Are Memories
Obtained Over Time?
• In the information processing model, information is
encoded in the brain during learning, stored in
memory, and then retrieved for later use.
• Alternatively, Atkinson and Shiffrin’s three-part
model consists of sensory memory, short-term
memory, and long-term memory.
• Atkinson and Shiffrin’s model emphasizes that
memory storage varies in duration and capacity.
Sensory Memory Is Brief
• Sensory memory: a memory system that very briefly
stores sensory information in close to its original
sensory form
• Sensory memory consists of brief traces on the
nervous system that reflect perceptual processes.
• Sperling concluded that sensory memory persists for
about one-third of a second and then progressively
fades
• Sensory memories enable us to experience the world
as a continuous stream rather than in discrete
sensations, e.g. the way a movie projector plays a
series of still pictures
Working Memory Is Active
• Material is passed from sensory memory to short-term memory.
More recently, psychologists have come to think of short-term
memory as working memory.
– short-term memory: a memory storage system that briefly holds a
limited amount of information in awareness
– working memory: an active processing system that keeps different
types of information available for current use, e.g. sounds, images,
ideas
• Information remains in working memory for about 20 to 30 seconds
unless you actively prevent it from disappearing by thinking about
or rehearsing the information
– How long can you remember the three-letter string of consonants,
XCJ? Try to retain this information while counting backward in threes
from the number 309
• Retrieval, transformation, and substitution make distinct and
independent contributions to updating the contents of working
memory
“Memory Storage”
The movie Eternal Sunshine of the Spotless Mind depicts a
fictional way to erase the past, but what keeps our memories
around in the first place? As the ScienCentral News video
reports, brain researchers are beginning to unwind a new twist
on how we maintain memory.
Memory Span and Chunking
• Memory span refers to the amount of information held in
working memory
• George Miller noted a typical limit of 7 +/– 2 items in working
memory, although more recent evidence suggests it may be
limited to as few as 4 chunks of information
– chunking: organizing information into meaningful units to make it
easier to remember
• The capacity of memory span can vary among individuals, and
increases as children develop and decreases with advanced
aging
What strategies do you use for remembering?
Why do they work?
Long-Term Memory
Is Relatively Permanent
• Long-term memory is a relatively permanent,
virtually limitless store
• Long-term memory enables you to remember
nursery rhymes from childhood, the meanings
and spellings of words you rarely use, what
you had for lunch yesterday, etc.
– What are some of your earliest memories?
Distinguishing Long-Term Memory
From Working Memory
• The distinction between working memory and longterm memory has been demonstrated by studies
that investigated the serial position effect and
studies that investigated memory impairments
– serial position effect: The ability to recall items from a list
depends on order of presentation, with items presented
early or late in the list remembered better than those in
the middle
– This data pattern includes:
• primacy effect: better memory for items at the beginning of the
list (reflects long-term memory)
• regency effect: better memory for the items at the end of a list
(reflects working memory)
What Gets Into Long-Term Memory?
• Information is most likely to be transferred from
working memory to long-term memory if it is
repeatedly retrieved, deeply processed, or helps us
adapt to an environment
• Evolutionary theory helps explain how we decide in
advance what information will be useful
• Animals that can use past experiences to increase
their chances of survival have a selective advantage
over animals that fail to learn from past experiences
How can you apply this knowledge to your daily life?
7.4 How Is Information
Organized in Long-Term Memory?
• Discuss the levels of the processing model.
• Explain how schemas influence memory.
• Describe spreading activation models of
memory.
• Identify retrieval cues.
• Identify common mnemonics.
7.4 How Is Information
Organized in Long-Term Memory?
• When an event or some information is
important enough, you want to remember it
permanently.
• Human memory is stored according to
meaning.
Long-Term Storage
Is Based on Meaning
• Perceptual experiences are transformed into representations and stored in
networks of neurons
• Mental representations are stored by meaning
• Craik and Lockhart’s levels of processing model suggests the more deeply
an item is encoded, the more meaning it has, and the better it is
remembered
– maintenance rehearsal: repeating the item over and over
– elaborative rehearsal: encodes the information in more meaningful ways
• The more an item is elaborated at the time of storage, the richer the later
memory will be because more connections can serve as retrieval cues
• Brain imaging studies have shown that semantic encoding activates more
brain regions than shallow encoding and this greater brain activity is
associated with better memory
“Tip of the Tongue Learning”
When can’t quite remember somebody’s name, trying to
excavate if from your memory might be the worst thing you can
do, according to new psychology research. This ScienCentral
News video explains.
Schemas Provide
an Organizational Framework
• Decisions about how to chunk information
depend on schemas
– schemas: cognitive structures that help us
perceive, organize, process, and use information
• Culture shapes our schemas and can lead to
biased encoding
• Schemas influence memory
Information Is Stored
in Association Networks
• Collins and Loftus’s model of networks of associations where each
unit of information about an item is a single node in the network
– For example, “red,” “vehicle,” “emergency” for “fire truck”
• The closer the nodes, the stronger the association between them
and therefore the more likely it is that activating one node will
activate the other
• Spreading activation models: stimuli in working memory activate
specific nodes in long-term memory, making retrieval easier
• Activation of a node spreads throughout its network, enhancing
memory of related items
• Semantic links exist between related items
• Associative networks are organized by category and structured in a
hierarchy; they provide a blueprint for where to find information
Retrieval Cues Provide Access
to Long-Term Storage
• Retrieval cues, including contextual cues and internal states,
help us access stored information
– retrieval cue: anything that helps a person (or a nonhuman animal)
recall information stored in long-term memory
• According to Tulving’sencoding specificity principle, any
stimulus encoded along with an experience can later trigger a
memory of the experience
• Memory may be enhanced by:
– context-dependent memory: when the recall situation is similar to the
encoding situation
– state-dependent memory: when a person’s internal states match
during encoding and recall
“Bloody Teeth Boost Memory”
Why do we remember emotional events so well? One memory
researcher says it’s not just because they’re important to us.
As this ScienCentral News video reports, the findings suggest
that we can manipulate emotion to help improve our memory.
Mnemonics
• Mnemonics, such as the method of loci and
verbal mnemonics, involve the use of retrieval
cues to improve recall
– mnemonics: learning aids, strategies, and devices
that improve recall through the use of retrieval
cues
– method of loci (memory palace): consists of
associating items you want to remember with
physical locations
7.5 What Are the Different
Long-Term Memory Systems?
• Distinguish between episodic, semantic,
implicit, explicit, and prospective memories.
• Generate examples of each of these types of
memory.
7.5 What Are the Different
Long-Term Memory Systems?
• Long-term memory is composed of multiple
systems.
• Long-term memories can differ in how they
are acquired and how they are stored and
retrieved.
Explicit Memory
Involves Conscious Effort
• Fundamental differences exist among episodic
and semantic memory, explicit and implicit
memory, and prospective memory
– implicit memory: the system underlying
unconscious memories
– explicit memory: the system underlying conscious
memories
• declarative memory : the cognitive information
retrieved from explicit memory; knowledge that can be
declared
Explicit Memory
Involves Conscious Effort
• In 1972, Tulving found that explicit memory can be
divided into:
– episodic memory: memory for one’s personal past
experiences, e.g. remembering aspects of your 16th
birthday
– semantic memory: memory for knowledge about the
world, e.g. knowing what Jell-O is
• Evidence that episodic and semantic systems of
explicit memory are separate can be found in cases
of brain injury in which semantic memory is intact
even though episodic memory is impaired
Implicit Memory Occurs
Without Deliberate Effort
• Implicit memory consists of memories that exist without our
awareness of them and that do not require conscious attention
• Jacoby’s false fame effect demonstrated how our implicit formation
of attitudes can affect our beliefs about people
• Examples of implicit memory include procedural (motor) memory
and attitudes influenced by implicit learning:
– procedural (motor) memory: involves motor skills, habits, and other
behaviors employed to achieve goals, e.g. coordinating muscle
movements to ride a bicycle
• Procedural memories are generally so unconscious that most
people find that consciously thinking about automatic behaviors
interferes with the smooth production of those behaviors
Prospective Memory Is
Remembering to Do Something
• Prospective memory involves remembering to do
something at a future time. If a cue to remember is
available in the person’s environment, prospective
memory can operate automatically
• Remembering to do something takes up valuable
cognitive resources and reduces the number of items
we can deal with in working memory or the number
of things we can attend to
• Without a retrieval cue, remembering requires
conscious effort
– What sort of retrieval cues do you use to jog your
memory?
7.6 When Do People Forget?
• List the seven sins of memory.
• Explain transience, blocking, and
absentmindedness.
• Distinguish between retrograde and
anterograde amnesia.
• Discuss methods to reduce persistence.
7.6 When Do People Forget?
• Forgetting is the inability to retrieve memory from long-term
storage.
• The ability to forget is as important as the ability to
remember.
– What would life be like if you could not forget?
• Normal forgetting helps us remember and use important
information.
• Ebbinghaus’ so-called methods of savings provided
compelling evidence that forgetting occurs rapidly over the
first few days but then levels off.
• Schacter identified what he calls the seven sins of memory:
– transience, absentmindedness, blocking, and persistence are related to
forgetting and remembering
– misattribution, suggestibility, and bias are distortions of memory
Transience Is Caused by Interference
• Transience results from proactive or
retroactive interference
– proactive interference: when prior information
inhibits the ability to remember new information
– retroactive interference: when new information
inhibits the ability to remember old information
Blocking Is Temporary
• Blocking is a temporary inability to retrieve
specific information, as exemplified by the tipof-the-tongue phenomenon
• Blocking often occurs because of interference
from words that are similar in some way, such
as in sound or meaning, and that recur
Absentmindedness Results
From Shallow Encoding
• Absentmindedness is caused by shallow
encoding, which occurs when people fail to
pay sufficient attention
– In what ways can multi-tasking lead to
absentmindedness?
• During most of our daily activities we are
consciously aware of only a small portion of
both our thoughts and our behaviors
Amnesia Is a Deficit in
Long-Term Memory
• Amnesia is a deficit in long-term memory. This
condition results from disease, brain injury, or
psychological trauma
– retrograde amnesia: a condition in which people lose past
memories, such as memories for events, facts, people, or
even personal information
– anterograde amnesia: a condition in which people lose the
ability to form new memories
• H.M. had a classic case of anterograde amnesia; he
could remember old information, but after his
surgery he lost the ability to form new memories
Persistence Is
Unwanted Remembering
• Persistence is the recurrence of unwanted
memories; This problem is characteristic of
posttraumatic stress disorder
• The most common triggers of PTSD include events
that threaten people or those close to them
• Emotional events are associated with amygdala
activity, which might underlie the persistence of
certain memories
• Contemporary researchers are investigating methods
to erase unwanted memories
– Will reducing memories to take the emotional sting out of
life make us less human?
“Stress and Memory”
It’s as much a part of the holidays as presents and food.
We’re talking about stress. As this ScienCentral News video
explains, scientists are learning more about how it affects our
brains, from memory to the ability to make decisions.
7.7 How Are Memories Distorted?
• Define memory bias.
• Generate examples of source misattribution.
• Identify factors that contribute to errors in
eyewitness testimony.
• Discuss susceptibility to false memories.
• Describe contemporary views on repressed
memories.
• Discuss neuroscientific advancements in the
identification of true and false memories.
7.7 How Are Memories Distorted?
• Memory is far from a faithful, objective
recorder of facts and events.
• Research has shown that human memory is
biased, flawed, and distorted.
People Reconstruct
Events to Be Consistent
• People tend to recall their past beliefs and past
attitudes as being consistent with their current ones
– memory bias: the changing of memories over time so that
they become consistent with current beliefs or attitudes
• Groups’ collective memories can seriously distort the
past.
• Most societies’ official histories tend to downplay
their past behaviors that were unsavory, immoral,
and even murderous
• Individuals also tend to remember events as casting
them in prominent or favorable roles
Flashbulb Memories Can Be Wrong
• Some events cause people to experience what
Brown and Kulik termed flashbulb memories
– flashbulb memories: vivid episodic memories for
circumstances in which people first learned of a
surprising, consequential, or emotionally arousing
event
• They do not reflect the problem of
persistence, however, in that they are not
recurring unwanted memories
Do You Remember
Where You Were When…?
• Flashbulb memories can also be biased and
inaccurate
– For example, studies of the Challenger explosion and 9/11
demonstrate diminished recall several years later
• Timing affects research on the accuracy of flashbulb
memories
• Conway’s research showed that subjects who found
an event surprising and important had the strongest
flashbulb memories
“9-11 Flashbulb Memories”
Brain researchers have found that proximity counts when it
comes to how strong our memories are. While everyone
remembers where they were on September 11, 2001, when they
heard the news of the attacks on the World Trade Center, this
ScienCentral News video explains how those who were close to
the scene formed memories that still provoke the brain’s
response to danger.
Emphasis and Memory
• Any event that produces a strong emotional
response is likely to produce a vivid, although
not necessarily accurate, memory
– von Restorff effect:Adistinctive event might be
recalled more easily than a trivial event, however
inaccurate the result
• Greater media attention and exposure to
detail may encourage better memory
People Make Source Misattributions
• source misattribution: memory distortion that
occurs when people misremember the time, place,
person, or circumstances involved with a memory
– false fame effect: an effect that causes people to
mistakenly believe that someone is famous simply because
they have encountered the person’s name before
– sleeper effect: an argument initially is not very persuasive
because it comes from a questionable source, but
becomes more persuasive over time
Source Amnesia
• source amnesia: a type of amnesia that occurs
when a person shows memory for an event
but cannot remember where he or she
encountered the information
• The absence of early memories, childhood
amnesia, may be due to the early lack of
linguistic capacity as well as to immature
frontal lobes
Cryptomnesia
• Cryptomnesia: a type of misattribution that occurs
when a person thinks he or she has come up with a
new idea, yet has only retrieved a stored idea and
failed to attribute the idea to its proper source
• This mistake can later lead to an accusation of
plagiarism
– Do you agree with the judge’s ruling against Beatle George
Harrison, whose song “My Sweet Lord” sounded similar to
the Chiffons’ “He’s So Fine”?
People Are Bad Eyewitnesses
• Research has demonstrated that very few jurors are
willing to convict an accused individual on the basis
of circumstantial evidence alone
• People tend to make poor eyewitnesses: they often
fail to pay attention to the incidents and people they
observe, and they are suggestible to misleading
information
– How might change blindness affect an eyewitness’
testimony?
Cross-Ethnic Identification
• People are particularly bad at accurately identifying
individuals of other ethnicities or races
• Possible explanations:
– Greater activation in the fusiform face area may be
responsible for stronger memory of same-race faces
– People may encode race and ethnicity according to rules of
categorization, and they do not notice much about
individuals beyond this group description
Suggestibility and Misinformation
• Elizabeth Loftus’s studies on suggestibility concluded
that people can “remember” seeing nonexistent
objects
• Different wordings of questions altered the
participants’ memories of the event
– suggestibility: the development of biased memories from
misleading information
• Eyewitnesses might inadvertently develop stronger
memories for inaccurate details due to
reconsolidation, e.g. retelling their stories to police,
friends, and relatives
Eyewitness Confidence
• Eyewitnesses who are wrong are just as
confident as (or more confident than)
eyewitnesses who are right
• Strong confidence for minor details may be a
cue that the memory is likely to be inaccurate
or even false; eyewitnesses to real crimes tend
to be focused on the weapons or on the
action
People Have False Memories
• According to research by Loftus, you might
remember an incident, even if it did not happen
• Memories can be distorted, or even implanted, by
false information
• Imagining an event might lead to confusion of the
mental image with a real memory
• Children are particularly susceptible to false
memories being induced
– “Lost in the mall” incident example
Confabulation
• Confabulation, or “honest lying,” has been
documented among individuals with Capgras
syndrome, characterized by damage to the
frontal lobes and limbic system
– confabulation: the unintended false recollection
of episodic memories
• When questioned, patients try to make sense
of their recollections by adding facts that
make the story more coherent
Critical Thinking Skill:
Recognizing How the Fallibility of Human Memory
Can Lead to Faulty Conclusions
• Patterson refers to the tyranny of the eyewitness: people
generally believe eyewitnesses even though, as memory
researchers have shown, eyewitnesses are frequently wrong
• Unless an independent party can verify the information, it is
difficult to distinguish between a valid memory and a faulty
one
• When a memory is important to some outcome, consider
that memory’s likely accuracy and check it against related
objective facts
– Have you ever been an eyewitness to an accident or crime?
– Did your memory of the incident differ from someone else’s?
Psychology: Knowledge You Can Use—
How Can I Study More Effectively for Exams?
•
•
•
•
•
•
Distribute your learning
Elaborate the material
Practice
Overlearn
Use verbal mnemonics
Use visual imagery
To use all of these strategies, you need to remember them.
As a first step toward improving your study skills, create a
mnemonic to remember these strategies!
Repressed Memories
Are Controversial
• The legitimacy of repressed memories
continues to be debated by contemporary
psychologists, many of whom argue that such
memories may be implanted by suggestive
techniques, e.g. hypnosis and guided recall
• While research shows that some therapeutic
techniques seem especially likely to foster
false memories, it would be a mistake to
dismiss all adult reports of early abuse
Neuroscience May Make It Possible
to Distinguish between
“True” and “False” Memories
• Neuroscientists are attempting to develop
techniques to distinguish between true and
false memories on the basis of patterns of
brain activation
• One problem with this method is that false
memories tend to be similar in many ways to
true memories and may activate the same
area of the brain during retrieval
“False Food Memories”
If your first taste of potato chips or chocolate had made you
sick, your eating habits today might be different. As this
ScienCentral News video explains, psychology researchers
suggest that changing memories about food could change what
we choose to eat.
“Brain Viagra, Part 1”
Companies that sell herbal supplement gingko biloba say it can
enhance your memory. But as this ScienCentral News video
reports, scientific evidence on whether gingko works is
controversial at best.
“Brain Viagra, Part 2”
There’s a huge market for substances that claim to boost
memory, but when can we expect drugs designed and proven to
do so? As this ScienCentral News video reports, advances in
genetics research may help to make effective memory drugs a
reality.
Download