Why People Don’t Swarm: Evidence for a Dual-process
Memory Model in Collaborative Tagging
Center for Educational Technologies,
Narva Mnt 25, 10120 Tallinn, Estonia
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Knowledge Management Institute,
Graz University of Technology
Inffeldgasse 21a, 8010 Graz, Austria
+43 316 873 9566
We propose a dual-process memory model for incorporation into
current generative models of collaborative tagging. This would be
in line with a large body of research in cognitive psychology
showing dissociation of implicit and explicit memory processes.
We present initial findings from experimental studies that show
the reality of the two memory processes in collaborative tagging.
Our proposal has both theoretical and practical implications,
mainly in terms of gaining a better understanding of the
underlying processes in tagging and the differential impact that
different manipulations in tagging environments will have on
Categories and Subject Descriptors
H.1.2 [Information Systems]: User/Machine Systems - Human
information processing, H.5.3 [Information Interfaces and
Presentation]: Group and Organization Interfaces - Web-based
interaction, J.4 [Computer Applications]: Social and Behavioral
Science – Psychology,
Experimentation, Human Factors
Collaborative Tagging, Implicit and Explicit Memory, Process-
It has become customary to regard human behavior in the use
of social software systems as a form of swarming behavior. It
seems to be appealing to regard human action as simple imitating
behavior that only in combination with the behavior of others
leads to some form of intelligence. We think this disregards a long
history of research into human information processing.
Instead, we suggest that human behavior in the use of social
software is driven by a sophisticated internal knowledge
representation highly adaptive to the current task, and flexibly
used by means of metacognitive processes. In this paper, we take
collaborative tagging as a case in point and demonstrate how the
internal processes can be examined with a process dissociation
procedure. We show initial results that provide evidence for a
dual process account of encoding and retrieval from memory.
2. HUMAN MEMORY IN
When people use a collaborative tagging environment,
individual memory processes are likely to play a major role. In the
simplest case, one could differentiate these processes into
encoding and retrieval. When a user browses a collection or
searches, she observes the tags assigned to resources or displayed
as tag clouds and, hence, encodes the terms in individual memory.
When, on the other hand, she tags a resource herself, retrieval
from memory needs to take place that allows her to assign
In recent attempts to understand tagging behaviors, several
generative models of tagging have been suggested that allow for
simulating a user’s behavior during tagging. The purpose of these
models is to gain a better understanding of the emergent processes
that are assumed to play a major role in these types of
environments. These models – implicitly or explicitly – make
assumptions on memory processes during encoding and retrieval.
Our reading of the literature suggests that two alternative
conceptions have been proposed to account for these processes.
Either it is assumed that a simple form of imitation takes place
where tags previously used by others are used as tags for the
current resource. Terms are then drawn in a random process from
existing terms, and this process is influenced – among others – by
the frequency and recency of use , . Alternatively, it has
been suggested that cues during encoding or retrieval (e.g. the
tagged resources or other tags displayed) lead to deep conceptual
processing in which a conceptual semantic memory system is
called to generate appropriate terms to be used as tags ,.
In cognitive psychology research, it has long been suggested
that two types of memory processes play a role in all types of
retrieval tasks from memory (e.g. ). We will refer to
these here as implicit and explicit memory processes. While
explicit memory preserves the context from the study episode,
implicit memory does not support the conscious retrieval of the
study context. Retrieving from explicit memory involves an
experience of conscious and deliberate recollection, while
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retrieving from implicit memory is relatively automatic and
effortless and is associated with an experience of familiarity or
“just knowing” . While explicit memory is mainly responsible
for the conscious recollection in typical memory tests (e.g.
recognition or recall tests of studied material), implicit memory
facilitates performance on certain tasks (e.g. identification of
words or indicating preference for a stimulus) without conscious
intention of recalling the study episode.
Support for the empirical reality of this distinction has been
obtained through numerous experimental studies in which
dissociation of performance attributed to these two memory
processes could be observed. This means that both processes
contribute independently to a certain memory performance, and
that the systems can be influenced independently by different
manipulations, both during encoding or retrieval (e.g. ).
For example, semantic elaboration during encoding (e.g.
conceptually elaborating on an item when studying it) has a large
positive effect on explicit memory (e.g. consciously recalling the
item), which is consistently larger than on implicit memory (e.g
completing a word stem ). On the other hand, several
manipulations of processing fluency during retrieval (e.g. how
easy it is to read an item) have effects on implicit memory and no
effect on explicit memory (e.g. ).
3. EXAMINING DISSOCIATIONS: A
METHOD AND INITIAL RESULTS
Because implicit and explicit processing can not simply be
observed from behavioral data or from tag data in a tagging
environment, it is necessary to carefully design experimental
studies in which the two types of processes can be studied, and
devise sophisticated models that allow estimation of parameters
for these internal processes.
In our own research, we look at how users process tags they
observe in a collaborative tagging environment. For example, we
have tried to discern explicit and implicit memory processes with
an adapted process dissociation procedure initially suggested by
Jacoby (1991) . In this procedure, users first process tags in an
incidental processing conditions: they have to make decisions on
which content is more suitable by looking at tags assigned to that
content. In a second phase, they are then asked to intentionally
learn a number of tags from the same environment. When they are
tested for their memory of the tags in a later memory test, one
group is asked to name all tags (incidentally learned or
intentionally learned) while another group is asked to produce
only those tags that were intentionally learned.
A multinomial model  can then be used to obtain
independent estimates of probabilities for two memory processes
during retrieval, an explicit recollection (explicit) and a
familiarity-based judgment process (implicit).
Our initial findings firstly suggest that a dual process model
that involves independent retrieval processes from explicit and
implicit memory is suitable to explain performance in the memory
test after the search task. This is shown by significance of the
overall model and means that both processes contribute to
memory performance. Secondly, across several search task
conditions, we find that processes of explicit recollection are more
important for performance than implicit processes. This is
indicated by a significant difference in the two parameters.
Finally, we have found evidence that the two memory processes
can be selectively manipulated. To show this, we have instructed
users to search with different intentions (e.g. looking for material
for a private leisure activity vs. looking for material for a
homework assignment). Initial results indicate that estimates for
the memory processes do in fact vary with search intention. This
is in line with research showing that metacognitive strategies can
influence implicit and explicit memory processes .
4. CONCLUSIONS AND IMPLICATIONS
In concluding from the above, a dual process model as we
are suggesting should help us gain a better theoretical
understanding of collaborative tagging processes and the
underlying cognitive mechanisms. We see mainly two areas where
such enhancements would be beneficial. First, current generative
models that look at microprocesses in collaborative tagging would
benefit from incorporating a two-stage memory process as we are
suggesting. A formal approach as suggested above would lend
itself for inclusion into generative models of tagging. Familiarity-
based retrieval is usually conceptualized as decision process
involving a continuous variable with a varying response criterion
(strict or lenient), much the same as in a signal detection model of
memory. Explicit recollection, on the other hand, is characterized
as a discrete memory process that involves distinct states and
transitions of learning or forgetting  which could be captured
through a markov model.
Secondly, we assume that our dual process memory model
might shed new light on a recent attempt to explain tagging
motivations. Körner et al.  have proposed a typology of user
motivations, classifying users as describers or categorizers. This
assertion is mainly based on the observation of empirical tagging
behavior, whereas the theoretical underpinning of this model is
limited. We suspect that the two tagging patterns observed by
Körner et al. could be mapped to the two memory processes we
are suggesting, where the “describer pattern” would be driven
mainly by implicit memory processes, and the “categorizer
pattern” mainly by explicit ones.
Furthermore, our research has practical significance as well.
A dual process memory model for collaborative tagging would
suggest that different manipulations made in the tagging
environment will impact the two memory processes in different
ways, and hence have a differential impact on the generation of
tags in these environments. As a result, concrete hypotheses could
be proposed. As to manipulations during encoding, one would
expect that generating tags vs. simply reading through tags should
impact explicit memory processes more than implicit ones. The
same is to be expected for other manipulations that target deep
semantic processing during encoding (e.g. displaying tags as a
network of semantically related tags). During retrieval, on the
other hand, we would expect that tag recommendations given at
retrieval time would influence implicit memory processes more
than explicit memory processes. Also readability of these
recommendations (e.g. varying font size as is common in tag
clouds) should influence processing fluency and therefore impact
implicit memory processes more than explicit ones. Moreover,
different forgetting curves have been obtained for explicit as
compared to implicit memory representations .
We have only listed some of the more obvious hypotheses
above. We would argue that an integrated dual process model of
memory could make predictions about a large number of memory
phenomena during tagging, and – given the right experimental
paradigms – these could be systematically studied.
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