The
domain of language / crystallized knowledge has two main aspects:
a.
Semantics: our store or
fund of word or concept meanings. This includes lexical knowledge (knowledge of
words and their meanings) as well as general knowledge (our familiarity with
the environment and culture in which we live). We can assess this aspect using
tests such as vocabulary, similarities, and general information.
b. Syntax and grammar: rules that govern how words are put
together to form "legal" and meaningful sentences. We can assess this
aspect using tests such as the Sentence Comprehension, Word Structure and Formulated
Sentences in the CELF-5 .
Do verbal
and semantic fluency tests assess crystallized knowledge?
Semantic
fluency
A
semantic fluency test is not a good way to assess crystallized knowledge or
language. In a semantic fluency test, the child is asked to say as many words
as possible that belong to a certain category within one minute. Semantic
fluency tests deliberately use simple and easy categories, categories in which
it is clear that every child knows many members. One such category is, for
example, “animals.” It is reasonable to assume that every child knows the names
of many animals. The child’s challenge is not to show us how broad their
lexicon is, or how many animals they know. Therefore, the task is not concerned
with semantics.
In
this test, the child does not perform any processing of the grammatical
structure of the words, so it is clear that the task does not assess this
aspect of crystallized knowledge either.
If
we wanted to use the semantic fluency test to assess the extent of children's
crystallized knowledge, we would challenge them with a category that better
distinguishes between different children — a category in which we are not sure
that the vast majority of children know many members. Such a category could be,
for example, names of trees, or names of capital cities. These are more
difficult categories, and the children’s ability to retrieve members of each of
them is indeed influenced by the breadth of their crystallized knowledge.
Furthermore,
if we wanted to know the extent of children’s crystallized knowledge, we would
not limit the task in time, because the time dimension would not be relevant.
We would be interested only in the breadth of the children’s knowledge is in
those two categories.
If
a semantic fluency test does not challenge the child’s crystallized knowledge,
what does it measure?
The child’s challenge in a
semantic fluency test is to conduct an efficient search in the store of
crystallized knowledge. The child must organize the search within the
store of crystallized knowledge / long-term memory and retrieve from memory,
fluently, quickly, and efficiently, as many animal names as possible. For this
purpose, the child can use strategies — for example, beginning by retrieving
sea animals, and after exhausting that store, moving on to pets, farm animals,
and so on. Therefore, a semantic fluency test assesses the child’s retrieval
ability from long-term memory, that is, long-term storage and retrieval ability.
The purpose of choosing easy categories in semantic fluency tests is to
neutralize the crystallized-knowledge dimension of the task, and to focus the
task on assessing the process of retrieval from long-term memory.
Let
us recall that long-term storage and retrieval ability is not concerned with
the content of long-term memory — that content is our crystallized knowledge —
but rather with the processes
of storing information in memory and retrieving information from memory. The focus of the semantic fluency
task is on the fluency of retrieval from memory.
Verbal / phonemic fluency
A
verbal fluency test also does not assess crystallized knowledge or language. In
a verbal fluency test, the child is asked to retrieve as many words as possible
that begin with a certain letter within one minute. The child is not dealing
with semantics. The meanings of the words are not important for this test. It
is clear that every child knows many words that begin with every letter. Any
word with any meaning is accepted, provided that it begins with the required
letter. In this test, the child also does not perform any processing or
analysis of the grammatical structure of the words.
What
cognitive process does the child perform in verbal fluency tests?
In these tests, the child must
conduct an efficient search in the store of crystallized knowledge. For
this purpose, it is desirable that the child create a strategy — for example,
beginning to search according to the syllable /be/, and after exhausting that,
moving on to the syllable /ba/ or to the consonant blend /br/, and so on. Since
we are not accustomed to searching for information in memory according to
sound, the child must create a new strategy, and therefore executive functions have a strong
influence on this task. Since the meanings of the retrieved words are
not the focus here, but only the extent to which retrieval is fluent and rapid,
the test assesses the
efficiency of retrieval from long-term memory. Therefore, a verbal fluency test
assesses retrieval fluency, and not crystallized knowledge.
I
assume that performance on this test is influenced not only by retrieval
fluency and executive functioning, but also by auditory processing ability,
since the key to retrieving the words is the child’s ability to isolate the
phoneme (B), the syllable (ba) or the consonant blend (br) with which they
begin.
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