(Note:
In: K.W. Kallus, N. Posthumus & P. Jimenez (eds.) 2001.Current psychological
research in
What language tells us about immediate memory
span
Gertraud Fenk-Oczlon & August Fenk,
Die Studie beschäftigt sich mit dem nach wie vor aktuellen Problem (z.B. Shiffrin & Nosofsky 1994, Engle et al. 1999), wie denn das Konzept oder die Konzepte eines „Kurzzeitgedächtnisses“, eines „Arbeitsgedächtnisses“ und eines „immediate memory“ operational zu definieren seien – informational (in bits), als fixe Anzahl (von Elementen oder „chunks“ aus Elementen), oder als Zeitspanne. Anstatt, wie in der kognitiven Linguistik üblich, nach dem Erklärungswert kognitionspsychologischer Konstrukte für die Linguistik zu fragen, wird nun versucht, empirische Resultate crosslinguistischer Forschung (zuletzt: Fenk-Oczlon & Fenk 1999) zur Klärung der obigen Frage heranzuziehen. Dabei zeigt sich, daß die drei in der Psychologie diskutierten „constraints“ in der sprachlichen Segmentierung zusammenfallen: Sie werden manifest in der Dauer von Clauses, der pro Silbe transportierten Informationsmenge und der Anzahl von sieben plus minus zwei Silben pro Clause.
Thesis 1: The structure of natural language
contains information about the structure of our cognitive apparatus.
One may view language as a product of our
cognitive system or as the “Procrustean bed” of thinking; we may
view it as a subsystem of the cognitive system or view the cognitive system as
the most influential “environmental” system of language; or proceed from the
perspective of a co-evolution (Deacon 1997, Fenk-Oczlon & Fenk 1996) of
brain and cognition on the one hand and language on the other hand. Or assume
that the evolution of the language system was subject to the constraints of our
cognitive system, which would mean, that the cognitive system is the “Procrustean
bed” of language evolution. Not all of these perspectives are equally
plausible, and not all of them are mutually exclusive. But all of them have in
common that language must convey some information about the cognitive system.
Language can tell us something about this cognitive system. And it may well be
that it can tell us - in some respects at least - even more about the architecture
of our memory-system than the psychologists’ recall- and recognition
experiments with series of any sort of elements. This makes it tempting to turn
the table - i.e. to draw inferences from language-structure on cognition
instead of, as in former studies (Fenk-Oczlon & Fenk 1994), the other way
round.
Thesis 2: Time is a more or less explicit factor in any operationalization of the capacity of “short-term memory” and/or “working memory”.
Within cognitive
psychology there is an extensive discussion about possible distinctions between
components of the memory system (such as the “sensory buffer” and “short-“ and
“long-term memory” in Atkinson & Shiffrin 1968) and possible distinctions
between processors involved in short-term retention, such as “short-term
memory” and “working memory”. This debate is not new (c.f. Fenk-Oczlon &
Fenk 1995: 226 f.) but still actual (Engle et al. 1999). The central question
is of course the operationalization of capacity limitations. Regarding such
operationalizations Schweickert & Boruff (1986: 424) summarized: “...the
capacity of the short-term store is not determined by a fixed number of items,
bits or chunks, but by the limited time for which the verbal trace endures.”
But time is, for obvious reasons, also involved in operationalizations focusing
on bits and on chunks, because the dimensions in question are the “information
(in bits) per time” or the number of
items that is grasped “at a glance” (Miller 1994:348). If there is something
like a "fixed number of items” then it is most probably a fixed number of
items that can be processed within a fixed time intervall, i.e. within a phase
or cycle that is characteristic for our cognitive processing.
Thesis 3: Time, bits, and chunks - all three constraints affect language
segmentation.
In spoken language
there are only two entities corresponding to rhythmic processing - the syllable as the basic element and the
clause or intonation unit at a higher order level. (The unit “in between” these
two levels is the word. It is the most widely used material in memory experiments
and is of course interesting because of its semiotic status. But it is not the
appropriate candidate in the search for elements and components of rhythmic
organization.) Thus, a crosslinguistic experimental study (Fenk-Oczlon 1983)
was conducted in order to test the assumption that the number of syllables per “clause” would vary within the range of the
magical number seven plus minus two. The clauses used were of a special
quality: simple declarative sentences encoding one proposition in one intonation unit, such as blood is red or the sun is shining. 22
German sentences of this sort were presented to native speakers of 27 different
languages. Native speakers were asked to translate the sentences into their
mother tongue and to determine the length of the translated sentences in syllables. The results: The mean length was
6.43 syllables per sentence; the lower end of the distribution was marked by
Dutch with a mean value of 5.05 syllables and the higher end by Japanese with
10.2 syllables.
A statistical reanalysis (Fenk-Oczlon &
Fenk 1985) should clarify the question about the relevant factor determining
the position of single languages on the continuum “mean number of syllables per
sentence”. The factor coming under suspicion was the syllable-complexity, i.e.
a language’s mean number of phonemes per syllable. One cause of suspicion was
that the articulation of more complex syllables takes up more time. Another
cause was that Dutch is known for its complex syllables and Japanese for its
simple CV-syllables. The result was a highly significant negative correlation (
r = - 0.77, p <0.1%) between mean number of syllables per sentences and mean
number of phonemes per syllable. The interpretation: Languages with higher
syllable complexity need, proportionate to the higher expenditure of time per
syllable, fewer syllables for encoding a certain proposition. The whole set of
crosslinguistic correlations found in later studies (Fenk & Fenk-Oczlon
1993, Fenk-Oczlon & Fenk 1999) with a meanwhile extended sample of languages
conforms to this interpretation suggesting that all three constraints discussed
in psychology - time, information,
number of items - become manifest in
the rhythmic organization of language. Findings allow to bring together
different lines of argumentation - even in cases where the positions in
question are as yet discussed as incompatible with each other.
Regarding capacity
limits of immediate memory, Miller (1956) proposes a “constant” number (7 plus
minus 2) of elements or chunks of elements. Broadbent (1971:4) also argues for
limitations in the sense of a fixed number of items but assumes “that the
underlying number is more closely to three”. And Baddeley (1990: 74, 1994:
355) tends to replace any sort of fixed-number limitations by time related
limitations. The arguments of Schweickert & Boruff (1986:424) cited under our Thesis 2 is in
line with this time based approach. Our findings, however, are in line with
both approaches, the chunk based as well as the time based approach. Provided
that one succeeds in choosing measures relevant for rhythmic processing (number
of syllables per clause), time based limits and chunk
based limits coincide: A time span
of two seconds (plus minus one) comprises seven (plus minus two) syllables -
from five rather complex syllables up to nine or even ten very simple syllables.
This span of (about two seconds and) about seven syllables has, according to
our findings, the appropriate size for encoding one proposition. In this
respect our empirical results seem to have some impact on the propositional
theory for sentence processing (Kintsch 1974) and on approaches connecting
short-term memory with conscious processing. The span has the appropriate size
that allows to extract the meaning of a clause before moving to the following
clause. It has, to use Mandler’s (1975:236)
words, the size “that can be kept within the conscious field, the focal
attention.”
Last but not least
the empirical results conform to our theory of a relatively “constant” or
“invariant” flow of information in natural languages. Frequently used linguistic
units are shorter or get shorter (e.g. Zipf 1929, Mańczak 1980,
Fenk-Oczlon 1989, Fenk-Oczlon in press) and these shorter units contain,
because of their higher relative frequency, a lower amount of information. More
complex entities transmit, approximately proportionate to their longer
duration, more information than less complex entities. This seems to be valid
not only on the word level (Fucks 1964, Fenk & Fenk 1980), but, as the results reported show,
also on the level of more or less complex syllables.
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