Semantic memory is a form of declarative long-term memory and stands in contrast to episodic
memory (particular,personal time and place related events) as first suggested by Tulving (1972).
Semantic memory holds the general knowledge about the world. This can be for example in the
form of facts, skills, concepts or vocabulary and is therefore not related to emotions. Wheeler, Stuss
and Tulving (1997) specified the differences between episodic and semantic memory more concrete in
terms of their retrieval. Whereas episodic memory depends on a special kind of awareness, autonoetic
or self-knowing, which is experienced when people think back to a certain moment of their life-time
and remember former states of time, semantic memory only involves knowing or noetic awareness,
because people think without emotions or personal relation, and therefore objectively about what they
know.
In addition Wheeler et al. (1997) pointed out that semantic and episodic memory are closely
connected and that, due to the similar encoding, it is not possible to store some event (e.g. knowing a
new vocabulary) in semantic memory without encoding some kind of subjective experience in the
episodic memory. This holds also for the opposite direction.
There are different views concerning the brain regions that play an important role for semantic
memory. The two major opinions are first, that semantic memory is processed or stored by the same
brain regions as episodic memory (medial temporal lobes, hippocampal formation) and , opposing to
this, that these brain regions do not plain a role for semantic memory. Researchers supporting the
second opinion propose different alternatives. Some claim that the episodic memory gets encoded in
the neocortex, and others claim that the different aspects of one fact or concept are represented in
different brain, so for example sounds in the auditory cortex and visual representations in the visual
cortex.
Correlation between Language and Memory
Acquisition of language
According to Chomsky (1959) a child possesses innate neural circuitry specifically dedicated to
the acquisition of language. However, many psychologists and linguists believe that language is neither
entirely innate nor only acquired by learning.
Children possess an innate capacity for language and they acquire the language without special
training or feedback. Normally, babies start to speak the first words around their first birthday and
produce fluent grammatical sentences at the age of two or three. In contrast, other species fail to learn
at all. Children have the instinctive tendency to speak as babbling of babies show. In their first month
they are even able to discriminate speech sounds that are not discriminated in their parent's language.
Thereby, children perform a sophisticated acoustic and grammatical analysis of its parent's speech,
rather than correlating sounds with meaning or merely imitating speech. Although language is more
specific than general intelligence, it is not a specific system for language but rather a general capacity
to learn patterns: Every child will learn any language it is exposed to. Thus, there seems to be neural
system that analyzes communicative signal from other people according to the design of language.
70 | Cognitive Psychology and Neuroscience
Memory and Language
Speech production
Speech production processing is a more complex activity than one might think and requires several
skills. We have to think about what to say, then to select the right words, to order these words
grammatically finally express the sentence in actual speech. The speaker eases for the listener to
understand him by using prosodic clues as rhythm, stress and intonation. Generally, syntactic
boundaries (e.g. the ends of sentences) or grammatical junctures (e.g. the ends of phrases) are signalled
by hesitations or pauses.
Since speech is normally way too fast it is hard to identify processes involved in speech
production. Therefore, research focuses on speech errors in spoken language that can reveal how this
complex system might work. There exist several types of speech errors while selecting the correct
word. One kind of this lexical selection is semantic substitution where a word is replaced by another
with a similar meaning, and normally of the same form class (e.g. "week" instead of "day"). Blending is
the joining part of a word (or sentence) on to part of another (e.g. "breakfast" and "lunch" becomes
"brunch"). In the case of the word-exchange error two words switch their places. If inflections or
suffixes are attached to the wrong word, it is call morpheme-exchange error (e.g. "buyed").
Spoonerism is switching the initial letters of two or more words. Consonants are always exchanged
with consonants and vowels with vowels, and often similar phonemes are switched. Mostly, letters
within the same clause are switched which shows that a clause is an important unit in a sentence.
On the base of speech errors several theories have been developed. There is a strong similarity
among these theories and most of them agree on the following points: Pre-production planning of
speech, series of processing stages and procedure from the general to the specific. The spreading-
activation theory by Dell et al. is based on the assumption that a representation is formed at the
semantic, the syntactic, the morphological and the phonological level. Processing occurs at all four
levels, and is both parallel and interactive. So-called categorical rules define categories at each level
and dictate the required word. Nodes of the lexicon (network containing concepts, words, morphemes
and phonemes) become activated. The most activated node of the appropriate category is then selected
by insertion rules. A further approach is the theory by Levelt assumes that there is a network
containing three levels. The levels represent lexical concepts, lemmas or abstract words, and
morphemes. Activation proceeds only forwards and, the speech production involves a series of six
processing stages: Conceptual preparation (potential concepts are activated), lexical selection (lemma is
selected), morphological encoding (basic word form activated), phonological encoding (syllables of the
word are computed), phonetic encoding (speech sounds are prepared) and articulation. The theory is to
show that the word production proceeds from meaning to sound.
Diseases
The research on patients with brain lesions gives important evidence to the structure of the brain
and thus, to the function of certain brain regions. By these dysfunctions existing theories about memory
or language production can be tested or new hypothesises developed. Amnesia describes the loss of
memory and can among others be caused by a bilateral stroke, closed head injury or the Korsakoff's
syndrome (chronic alcohol abuse). Since brain damage is often widespread the function of a certain
area in the brain is problematic to determine. A further result of brain damage is aphasia, which is the
impairment of language abilities. There are several forms of aphasia, e.g. patients with Wernicke's (or
fluent) aphasia suffer from impaired language comprehension while patients with Broca's (or non-
fluent) aphasia are not able to speak properly.
Wikibooks | 71
Chapter 7
(For further information read the chapter Neuroscience of Language comprehension)
References
1. ↑ E. G. Goldstein, "Cognitive Psychology - Connecting Mind, Research, and Everyday Experience", page 137, THOMSON WADSWORTH TM 2005
External resources
Books
• “Cognitive Psychology: A Student's Handbook”, fourth edition, M. Eysenck, 2000
• “Cognitive Psychology – Connecting Mind, Research, and Everyday Experience”, E. Bruce
Goldstein (University of Pittsburgh), Thomson Wadsworth, 2005
• “Neuropsychology - The Neural Bases of Mental Function”, Marie T. Banich (University
of Illinois at Urbana-Champaign), Houghton Mifflin Company, 1997
• “PRINCIPLES OF NEURAL SCIENCE”, fourth Edition, international Edition, Erik R.
Kandel, James H. Schwartz, Thomas M Jessell, McGraw-Hill, 2000
Links
• http://www.almaden.ibm.com/institute/agenda.shtml ( Almaden Institute; Joaquin Fuster,
UCLA: Cortical Dynamics of Working Memory, 2006)
• http://www.brainconnection.com/topics/?main=fa/memory-language (Maxine L. Young,
2000)
• http://io.uwinnipeg.ca/~epritch1/sensmem.htm ( University of Winnipeg; Prof. Evan
Pritchard, PhD Attention & Memory, 2006)
• http://library.thinkquest.org/C0110291/science/research/basics/sensory.php
(ThinkQuest
Team)
• http://www.physiol.ox.ac.uk/~kk3/PP%2002%20Sensory%20Memory.ppt( U niversity of
Oxford, Department of Physiology, Anatomy and Genetics; Kristofer Kinsey PhD)
• http://www-static.cc.gatech.edu/classes/cs6751_97_winter/Topics/human-
cap/memory.html( G eorgia Tech, College of Computing; Harish Kotbagi, Human Capabilities(Memory), 1997)
• http://www.mtsu.edu/~sschmidt/Cognitive/sensory_store/sensory.html( M iddle Tennessee
State University; Stephen R. Schmidt, Copgnitive Psychology)
live version • discussion • edit lesson • comment • report an error
72 | Cognitive Psychology and Neuroscience
Imagery
8 IMAGERY
live version • discussion • edit lesson • comment • report an error
Introduction
ental imagery (varieties of which are sometimes colloquially refered to as "visualizing," "seeing
Min the mind's eye," "hearing in the head," "imagining the feel of," etc.) is quasi-perceptual
experience; it resembles perceptual experience, but occurs in the absence of the appropriate external
stimuli. It is also generally understood to bear intentionality (i.e., mental images are always images of
something or other), and thereby to function as a form of mental representation. Traditionally, visual
mental imagery, the most discussed variety, was thought to be caused by the presence of picture-like
representations (mental images) in the mind, soul, or brain, but this is no longer universally accepted.
Very often, imagery experiences are understood by their subjects as echoes, copies, or
reconstructions of actual perceptual experiences from their past; at other times they may seem to
anticipate possible, often desired or feared, future experiences. Thus imagery has often been believed to
play a very large, even pivotal, role in both memory (Yates, 1966; Paivio, 1986) and motivation
(McMahon, 1973). It is also commonly believed to be centrally involved in visuo-spatial reasoning and
inventive or creative thought. Indeed, according to a long dominant philosophical tradition, it plays a
crucial role in all thought processes, and provides the semantic grounding for language. However, in
the 20th century vigorous objections were raised against this tradition, and it is now widely repudiated.
The Imagery Debate
What is it about?
Visual imagery is a flow of thoughts you can see, hear, feel, smell, or taste. Visual imagery is a
window on your inner world, a way of viewing your own ideas, feelings, and interpretations. But it is
more than a mere window ---why---It is a means of transformation and liberation from distortions in
this realm that may unconsciously direct your life and shape your health.
Imagination, in this sense, is not sufficiently valued in our culture.
Without imagination, humanity would be long extinct.
Visual imagery is probably best known for its direct effects on physiology. Through imagery, you
can stimulate changes in many body functions usually considered inaccessible to conscious influence.
How is it?
The original imagery debate is concerned with the question how cognitive mechanisms in the brain
function when imagining pictures. First attempts at explaining these processes simply dealt with how
during real visual stimuli the light (photons) hits the retina where the picture is decomposed and
Wikibooks | 73
Chapter 8
reassembled again in the brain. Similar processes occur in the brain in the absence of visual stimuli
during the act of imagery. Pictures are produced in our mind without an actual visaul input. Modern
cognitive psychologists rather deny the production of pictures in the brain because then, there has to be
something (Homunculus) that continuously looks at the pictures and interprets them. Because of the
lack of reasonable explanations a behaviourist theory arose that opposed the view that pictures are
actually projected into the brain.
Today's imagery debate is mainly influenced by two opposing theories: (1) Zenon Pylyshyn’s
propositional theory and (2) Stephen Kosslyn’s depictive representation theory of imagery processing.
Pylyshyn idea is that information is stored in the brain in a propositional manner. The sentences “the
sun is shining” and “it’s the case that the sun is shining” have the same proposition, namely “shining
(sun)” which is stored in a Meta language (all propositions are of the form predicate(arguments)).
Contradicting Kosslyn states that there has to be some kind of spatial image representation. His image-
scanning experiments discovered that we actually create a mental picture of scenes while trying to
solve small cognitive tasks. Kosslyn argued that the responsible mechanisms involve a spatial
representation which is similar to the way we conceive things by actually perceiving them. Other
advocates of the depictive representation of scenes in our mind, Shepard and Metzler, developed the
mental rotation task. Two objects are presented to a participant in different angles and his job is to
decide whether the objects are identical or not. The result shows that the reaction times increases
linearly with the rotation angle of the objects. This phenomenon can’t be explained by a propositional
model, but instead implies that participants mentally rotate the objects in order to match the objects to
one another. This process is called mental chronometry.
The actual difference between imagery and perception occurs in their distinct processing
behaviour. Perception is a bottom-up process that originates with an image on the retina, whereas
imagery is a top-down mechanism which originates when activity is generated in higher visual centers
without an actual stimulus. Another distinction can be made by saying that perception occurs
automatically and remains relatively stable, whereas imagery needs effort and is fragile.
Biological reasoning of debate
Partially imagery is represented by certain neurons in our medial temporal lobe which might
respond to one image, but not to another (category-specific neurons). Lesion techniques have advanced
the research on the representation of imagery in our brain. For example, the size of our mental images
decreases when our primary visual cortex is damaged. There are also such phenomena as unilateral
neglect where the patient simply neglects half of his visual field. This occurs both when perceiving and
when imagining an object or a scene. The deficit, also called hemi-neglect, is usually due to a lesion in
the right hemisphere (most likely the superior temporal gyrus).
Spatial Representation
Abstract
This target article reviews evidence for the functional equivalence of spatial representation of
observed enviroment and environments described in discourse. It is argued that people possess a spatial
representation system that constructs mental spatial models on the basis of perceptual and linguistic
74 | Cognitive Psychology and Neuroscience
Imagery
information. Evidence for a distinct spatial system is reviewed.
Introduction
1.1 Space can be understood through perception and language, but are the mental representations
of space the same in both cases? Evidence for this position comes from a number of areas, including
mental imagery , such representations appear to be equivalent in form and operation to representations
of observed environments.
1.2 A number of empirical effects observed in spatial learning studies can be obtained when
subjects do not study a map or physical route but instead read a description of an environment.
1.3 People's spatial representations of descriptions can be seen to interact with perceptual spatial
systems.
1.4 Further evidence that spatial descriptions are represented in a spatial format comes from the
study of mental models. People generally represent texts in mental models rather than by retaining the
linguistic structure of the text
1.5 Although most research on mental models has focussed on text comprehension, researchers
generally believe that mental models are perceptually based .Indeed, people have been found to use
spatial frameworks like those created for texts to retrieve spatial information about observed scenes
(Bryant, 1991). Thus, people create the same sorts of spatial memory representations whether they read
about an environment or see it themselves.
What is it?
People create the same sorts of cognitive maps and mental spatial models from verbal descriptions
and direct observations. This suggests that people have a distinct spatial representation system that
creates spatial models from disparate sources of input and is independent of memory systems for other
domains of knowledge. The primary role of the SRS is to organize spatial information in a general form
that can be accessed by either perceptual or linguistic mechanisms. The SRS provides the coordinate
frameworks in which to locate objects, thus creating a model of a perceived or described environment.
The advantage of a coordinate representation is that it is directly analogous to the structure of real
space and captures all possible relations between objects encoded in the coordinate space. These
frameworks also reflect differences in the salience of objects and locations in accord with properties of
the environment and the ways in which people interact with it . Thus, the SRS creates representations
that are models of the physical and functional aspects of the environment.
How is spatial knowledge encoded?
What, then, can be said about the primary components of cognitive spatial representation?
Certainly, the distinction between the external world and our internal view of it is key, and it is helpful
to explore the relationship between the two further from a process-oriented perspective.
The classical approach assumes a complex intern al representation in the mind that is constructed
through a series of specific perceived stimuli, and that these stimuli generate specific internal
Wikibooks | 75
Chapter 8
responses. Research dealing specifically with geographic-scale space has worked from the perspective
that the macro-scale physical environment is extremely complex and essentially beyond the control of
the individual. This research, such as that of Lynch and of Golledge and his colleagues, has shown that
there is a complex of behavioral responses generated from correspondingly complex external stimuli,
which are themselves interrelated. Moreover, the results of this research offers a view of our
geographic knowledge as a highly interrelated external/internal system. Using landmarks encountered
within the external landscape as navigational cues is the clearest example of this interrelationship.
The rationale is as follows: We gain information about our external environment from different
kinds of perceptual experience; by navigating through and interacting directly with geographic space as
well as by reading maps, through language, photographs and other communication media. With all of
these different types of experience, we encounter elements within the external world that act at
symbols. These symbols, whether a landmark within the real landscape, a word or phrase, a line on a
map, or a building in a photograph, trigger our internal knowledge representation and generate
appropriate responses. In other words, elements that we encounter within our environment act as
knowledge stores external to ourselves.
Each external symbol has meaning that is acquired through the sum of the individual perceiver's
previous experience. That meaning is imparted by both the specific cultural context of that individual
and by the specific meaning intended by the generator of that symbol. Of course, there are many
elements within the natural environment not "generated" by anyone, but that nevertheless are imparted
with very powerful meaning by cultures (e.g., the sun, moon and stars). Manmade elements within the
environment, including elements such as buildings, are often specifically designed to act as symbols as
at least part of their function. The sheer size of downtown office buildings, the pillars of a bank facade
and church spires pointing skyward are designed to evoke an impression of power, stability or holiness,
respectively.
These external symbols are themselves interrelated, and specific groupings of symbols may
constitute self-contained external models of geographic space. Maps and landscape photographs are
certainly clear examples of this. Elements of differing form (e.g., maps and text) can also be