1.Introduction a sequence of e.g. Stroke(aphasias), Alzheimer disease,

1.Introduction

To
begin with, it has been proved that there is an asymmetry in human
brain, which is associated with complementary functions. In
particular, the central functions which are related to language,
reason and will power, are located in the left hemisphere of the
brain. On the other hand, the right hemisphere specialized on
creativity and intuition ( Corballis 2014)

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Additionally,
any damage in the left hemisphere of the brain as a sequence of e.g.
Stroke(aphasias), Alzheimer disease, Parkinson disease, dementia,
cerebral palsy etc. can affect the lexical access (individual’s
access in mental lexicon and right selection of meanings) of humans
in their mental lexicon (the way that words are stored in human’s
long-term memory). In other words, patients in these cases may
develop difficulties for instance in word retrieval making semantic
errors, which are produced in their spoken and written output,
phonological mistakes or fragment production of words, phonological
to graphemic conversion may also be influenced and auditory and
written comprehension might be impaired. What is more , frequency,
imageability and length effects are often presented, which means that
more highly imageable, more frequent and shorted words are accessed
and produced more easily in these cases ( Whitworth et al 2005).

According
to I.Taylor & M.Taylor (1990) the science of psycholinguistics
studies the relationship between language behavior and psychological
processes (see also Alexaki 2010).

Moreover,
the detection of damages to the language processing in the human
brain can be measured by neurophysiological techniques related to
electrical activity of the brain like: ERP (event related brain
potentials), FMRI(functional magnetic resonance imaging) and MEG
(magneto encephalography). However, these are also a lot of
behavioral research methods of psycholinguistics which in contrast
study and are based on behavioral dependent variables. This kind of
methods are also more appropriate for this assignment because they
contribute to the detection of the nature of difficulties, in terms
of the analysis and correct interpretation of them, connected to
impairments in the process of lexical access, developed by patients
with damages in the left hemisphere of the brain. Thus, accuracy and
effectiveness is succeeded in therapeutic intervention. For instance,
some of these methods are: speed accuracy trade-off (SAT), priming,
lexical decision, gating technique, visual word paradigm-eye
tracking, self-paced reading, rapid serial visual presentation
(RSVP), analysis of speech errors, picture/word naming and
referential communication task ( Garrod 2006).

Furthermore,
there is another distinction, about psycholinguistic research methods
between on-line techniques (that measurements take place at the same
time with language processing) and off-line techniques(that
measurements are related to subsequent results of processing).
On-line techniques are also considered more adequate than off-line,
because they give to researchers the opportunity to investigate the
data at real time , when patients give spontaneous answers without
having extra time to think or prepare better their answers (Garrod
2006).

Therefore,
it follows an analysis of some of the on-line behavioral
psycholinguistic research methods and in particular , the priming
with its subcategories, the lexical access and the self-paced reading
.

2.On-Line Processing
Tasks

2.1
Priming

According
to Gulan and Valerjev (2010), priming is referred to an augmented
sensitivity,that the subject seems to perform,to a particular
stimuli,activated by prior experience. Priming is considered to be
an implicit method that can facilitate the direct retrieval of
lexical information and access and it is mainly characterized as
subconscious and involuntary .In other words ,when the patient is
exposed to a prime item ,which might be a word with a specific form
or meaning or a whole sentence with a particular syntactic
structure,this prime item may affect the recognition comprehension
and retrieval of the subsequent target item through the reflection of
a connection between mental representations of prime and target item
(see also Garrod 2006).Consequently ,it is maintained that priming
can either increase the speed needed to recognize the second
target-item (facilitation) or it decreases the speed in order to
identify the target (inhibition).In particular the extend to whether
priming will have a facilitatory or an inhibitory effect ,depends on
the choices of words and their connection in terms of orthography
,semantics,morphology,phonology etc.

Furthermore
,it is useful to mention the different types of priming used :
repetition priming involves the technique of repeating a word again
and again aiming to make this word easier to recognize when you see
it again for example table (prime) , table (target ). Another type
is reffered to as semantic priming, and it describes the process of
the presentation of the two words(prime ,target) that must be
related in meaning(e.g. appropriate or adequate).It could be argued
that the direct retrieval of the target item is likely to be
facilitated because the two words that the are related in meaning can
after co-occur in a sentence (see also Klempin
2012),(Ferre,Sanchez-Casas 2014).A third type of priming is called
orthographic priming and is directly related to the visual and
written form of a word ,that is ,the two words (prime and target )
must be similar in orthography (e.g. fake,lake).Last but not least,
morphologic priming occurs when the two words are morphologically
similar (cat,cats).

At
this point ,it is more than useful to mention the conclusions drawn
by Milberg
,Blumsten and Dworetzky (1987) after conducting and experiment using
the priming method .They implemented priming in two clinical
groups,fluent (Wernicke’s aphasics) and non-fluent (Broca’s
aphasics ) compared to a control group .The experiment showed that
fluent aphasics had similar performance to the control group, unlike
Broca’s.

Consequently
, priming was proved to be a useful tool so as to detect the
preservation or not ,of the ability to make semantic judgment and
eventually maintain the lexical access,to a certain extend.(
Fumagalli de Salles et al 2012).

2.2
Lexical Decision

Another
effective on-line technique is lexical decision. This task is used in
order to measure how quickly a subject , presented with a string of
words, is able to accurately identify whether this is a word (e.g.
Greek) or a non-word (e.g. Greak) (Bonin et al 2001).

Notably,
through this procedure, the point of attention is on the time needed
by the subject, in order to decide whether the mixture of letters is
a real word or not. This time is indicating the extend to which the
subject can access his/her mental lexicon. Moreover, a rather common
effect of this type of task is described by the observation that
words that are more frequently encountered than others are recognized
faster. So, it is only logical to conclude that common words seem to
have a stronger mental representation compared to less common ones
(Wagenmakers 2004).

Another
point that has to be mentioned about the lexical decision technique
is that various recent
studies
have underlied the fact that this method extends beyond a mere
lexical activation. To be more specific, experiments have shown that
non-word lexicality is a striking example of the importance of
decisional and strategic process. That is to say, In cases where the
strings of letter presented to the subjects, looked less like real
words, subjects responded more easily to word stimuli and the
word-frequency effect described above, seemed to be weaker. One could
fairly infer that such results serve as a clear, indicator that when
lexical decision is performed , includes the ability to process

pseudowords
( Wagenmakers 2004).

Susan
Edwards (2005) in her book “Fluent Aphasia” includes a study by
Shapiro,Gordon,Itack and Killackey(1993) .They conducted three
experiments in their effort to investigate real-time access of
verb-argument structures in a group of Broca’s aphasic and a group
of Wernicke’s aphasic participants. In these experiments the method
used was the lexical decision. In one of them the subjects listened
to sentences over headphones as they were seeing a word flashing on a
screen, they had to decide whether it was a real word or not.
Experimenters recorded the reaction time and found that Broca’s
aphasics seemed to have more difficulties in recognizing different
types of verbs in active or passive sentences. In
contrast with Broca’s aphasics, Wernicke’s
aphasics demonstrated shorter reaction times regardless of the type
of sentences.

2.3
Self-paced Reading(SPR)

Last
but not least,self paced reading (SPR) is a very commonly used
on-line task which is aimed to measure how participants interpret
ambiguous sentences or words.More specifically ,through this
computerized method (Jegerski 2014) ,the reader determines the rate
of the presentation sentence by sentence ,phrase by phrase or word by
word,by pressing a button as soon as he/she has understood each
segment until the entire sentence has been read.It should be noted
that each time the reader presses the button ,the experimenter
records the pace of the presentation.Therefore, the time needed to
read each segment provides insight to the reader’s difficulties in
comprehension (Carrod 2006).

This
technique provides useful data with regard to syntactic analysis
,discourse comprehension and resolution of anaphors .However, in
self-paced reading tasks it has been observed that, when readers are
presented with smaller linguistic units, such as words and not
sentences , the former seemed to be read much more slowly, thus
interfering most with a normal reading process (Marinis 2010).

Gayle
Dede(2013)
in her article “reading and listening in people with aphasia :
effects of syntactic complexity ” ,refers to a study which was
intented to measure how

on-line
syntactic complexity is comprehended in written and spoken sentence
by people with aphasia and a control group of adults .In
these experiments the method used was self-paced reading and
listening tasks.

The
results show that syntactic complexity affected the participants in
the on-line performance in both groups, meaning
that, both groups seem to have similar effects. More specifically,
this phenomenon was especially apparent throughout the reading task.

3. Conclusion

Taking
everything into consideration, it could be concluded that lexical
access consists a fundamental mental process, which has been proved
that is highly likely to be affected in patients suffering from
impairments in the left hemisphere of the brain. What is more, the
above described psycholinguistic on-line methods, as priming,
self-paced
reading and
lexical decision, when used in such cases, could contribute to
successfully detect the degree to which a patient’s mental lexicon
has been impaired and whether or not he/she preserves the ability to
access his/her stored lexical information. For example, the
experiments described above have shown that these three techniques
can provide significant information to the experimenters. In
other words, the experiment carried out with the use of priming
helped ascertain that fluent aphasics had equal performance with the
control group. The
experiment based on the lexical decision method measured the reaction
times of the participants,
so as to decide, whether the words they were seeing on the screen
were real words or pseudowords. Finally,
in the self-paced
reading
experiment, both aphasics and the control group seemed to process
syntactic complexity in the same way, suggesting that their lexical
access ability regarding syntactic complexity was similar. That
being said, it could safely be argued that researchers and
experimenters should adopt and include these methods by designing
various on-line tasks, based on these techniques, alone or even
combined with other on- line techniques available. The
purpose is to maximize
the possibility to fulfill their therapeutic

goals resulting from the correct diagnosis.

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