<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Workshop on Computational Humanities Research, November</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Cultural Accumulation and Improvement in Online Fan Fiction</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Federico Pianzola</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
          <xref ref-type="aff" rid="aff3">3</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Alberto Acerbi</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Simone Rebora</string-name>
          <xref ref-type="aff" rid="aff2">2</xref>
          <xref ref-type="aff" rid="aff4">4</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Brunel University London</institution>
          ,
          <addr-line>Uxbridge, UB8 3PH</addr-line>
          ,
          <country country="UK">United Kingdom</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Sogang University</institution>
          ,
          <addr-line>35 Baekbeom-ro, Daeheung-dong, Mapo-gu, Seoul</addr-line>
          ,
          <country country="KR">South Korea</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>University of Basel</institution>
          ,
          <addr-line>Petersplatz 1, 4051 Basel</addr-line>
          ,
          <country country="CH">Switzerland</country>
        </aff>
        <aff id="aff3">
          <label>3</label>
          <institution>University of Milan-Bicocca</institution>
          ,
          <addr-line>Piazza dell'Ateneo nuovo 1, 20126 Milan</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
        <aff id="aff4">
          <label>4</label>
          <institution>University of Verona</institution>
          ,
          <addr-line>Lungadige Porta Vittoria 41, 37129 Verona</addr-line>
          ,
          <country country="IT">Italy</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2020</year>
      </pub-date>
      <volume>1</volume>
      <issue>4</issue>
      <fpage>8</fpage>
      <lpage>20</lpage>
      <abstract>
        <p>We analyse stories in Harry Potter fan fiction published on Archive of Our Own (AO3), using concepts from cultural evolution. In particular, we focus on cumulative cultural evolution, that is, the idea that cultural systems improve with time, drawing on previous innovations. In this study we examine two features of cumulative culture: accumulation and improvement. First, we show that stories in Harry Potter's fan fiction accumulate cultural traits-unique tags, in our analysis-through time, both globally and at the level of single stories. Second, more recent stories are also liked more by readers than earlier stories. Our research illustrates the potential of the combination of cultural evolution theory and digital literary studies, and it paves the way for the study of the efects of online digital media on cultural cumulation.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;cultural evolution</kwd>
        <kwd>cumulative culture</kwd>
        <kwd>Harry Potter</kwd>
        <kwd>digital literary studies</kwd>
        <kwd>fan fiction</kwd>
        <kwd>literature</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        In many cultural domains we can observe a progress through cumulative improvements. The
efficiency of information storage, just to take a familiar example, increased through centuries
with a series of innovations, in a process that continues today: a contemporary smartphone
can store thousands of books. In cultural evolution theory this process is broadly described as
cumulative cultural evolution [
        <xref ref-type="bibr" rid="ref5 ref7">9, 11</xref>
        ].
      </p>
      <p>
        There are no universally agreed measures of cumulation [
        <xref ref-type="bibr" rid="ref7">11</xref>
        ], but it seems a sensible
assumption that its degree difers in diferent cultural domains. In some domains, such as technology,
we can observe clear marks of accumulation, while in others, such as arts, even if accumulation
is not absent [
        <xref ref-type="bibr" rid="ref11 ref14">19, 16</xref>
        ], its scope appears limited. Many factors could explain why the degree of
accumulation difers as such, but two are particularly interesting for cultural evolution. One
is availability, that is, the number of possible models or cultural traits one has at disposal.
While the exact details are debated [
        <xref ref-type="bibr" rid="ref4">8, 20</xref>
        ], the basic idea is that more versions of the same
item available to copy from increase the probability that the item will be successfully
preserved. The second is fidelity. Cultural transmission is a noisy process. Transmission chain
experiments show that information transmitted orally tend to be lost and transformed [
        <xref ref-type="bibr" rid="ref13">18</xref>
        ]. In
some cases, populations of individuals converge on similar cultural traits without the need of
accurate passage of information, because of various constraints [
        <xref ref-type="bibr" rid="ref9">5, 13</xref>
        ]. In other cases, however,
information needs to be preserved and successfully transmitted to allow the reproduction of a
cultural trait [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]: modern complex technologies are preserved by virtue of supports that allows
faithful transmission.
      </p>
      <p>
        The contemporary difusion of online digital media produces an increase of availability and
ifdelity in several domains [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. A pertinent question is then what the consequences for cultural
cumulation are; whether this results in more improvement, or perhaps more improvements in
domains where it was limited before, because of relative lack of availability and fidelity.
      </p>
      <p>
        To start answering this question we analyse cultural cumulation in AO3, the biggest fan
ifction archive for stories in English. Previous research on fanfiction has found, for example,
that authors improve their writing skills in time, widening the range of their vocabularies
[
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. Here we focused on two features of cultural cumulation explicitly derived from cultural
evolution theory: accumulation and improvement. Accumulation refers to an increase in the
number of diferent cultural traits, while improvement refers to the fact that more recent traits
are ”better”, according to some metrics. (The third feature of cumulative culture discussed
in [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], ratcheting, that is, the fact the new innovations draw on previous innovations, is not
analysed here).
      </p>
      <p>
        Literary studies have theorized the historical increase in complexity (accumulation) of
literature, for instance, with the introduction of formal innovations by literary modernism (e.g.
stream of consciousness) and postmodernism (e.g. self-reflexivity) [
        <xref ref-type="bibr" rid="ref6">10</xref>
        ]. More problematic is
the case of improvement. The quality of literary works has been traditionally judged by a
restricted group of people, publishers and literary critics, who decided which texts deserved to
be included in the literary canon, often based on a criterion of originality, i.e. the presence of
some rhetorical or stylistic innovation in linguistic expression. This kind of institutionalised
prestige has often been opposed to the popularity of bestselling fiction [
        <xref ref-type="bibr" rid="ref10">15</xref>
        ], appreciated by
many because of its serial replication of known plot schemes or themes. More broadly, the
issue concerns the contrast between a narrow selection of canonized works and the entirety
of the archived literary production [
        <xref ref-type="bibr" rid="ref8">12</xref>
        ]. Fanfiction is an example of popular literature,
produced in a context in which social exchange, collaborative work, and fidelity to the canon or
to fandom tropes is the norm. In contrast, professional authors have often worked alone and
pursuing originality in the history of literature. In this context, we think it is appropriate
to talk about improvement in terms of cumulative culture, which focuses on the reception of
cultural artefacts and their widespread popularity as a measure of improvement [
        <xref ref-type="bibr" rid="ref7">11</xref>
        ]. On the
other hand, it might be the case that our model is not directly applicable to canonical literature
because power relationships and prestige influence that cultural field more strongly than they
do with fanfiction.
      </p>
    </sec>
    <sec id="sec-2">
      <title>2. Methods</title>
      <p>We chose to work with AO3 data because they are freely accessible, scraping of the website
is allowed and supported by the developers maintaining the servers, and there is an excellent
metadata system based on organized tags (Table 1). In addition, when uploading a story on
AO3, authors can add various kinds of tags, among which: fandom tag, to signal the fictional
universe/es to which the story is related (e.g. ”Harry Potter - J. K. Rowling”); character tag,
to list the characters appearing in the story (”Hermione Granger”); relationship tag, to list the
relationship/s in which the story characters participate (e.g. ”Draco Malfoy/Harry Potter”);
freeform tag, which can be related to any other aspect of the story (e.g. ”POV Draco”), the
fandom (e.g. ”Community: daily_deviant”), or fanfiction writing’s conventions (e.g. ”Ron
Weasley bashing”).</p>
      <p>AO3 has a system of tag wrangling, i.e. volunteers that continuously monitor newly
introduced tags aggregating them with existing ones—without replacing them—when they refer to
the same characters/relationships/themes. In our analysis we relied on this tag aggregation,
which we implemented thanks to the creation of a linked-data knowledge base mapping all
”synonym” tags used [14].</p>
      <p>We collected all metadata of the stories tagged with the fandom tag ”Harry Potter - J. K.
Rowling” (217,772 stories), including all tags and information listed in Table 1. We excluded
stories not in the English language, stories with less than 10 words, and stories published in
2020, obtaining a final sample of N = 196,726 stories. Fans started uploading their stories
on AO3 since November 2009, when the archive became publicly accessible. However, some
of the stories in AO3 are imported from previous publications or have been written in the
past. In such cases, authors can backdate their stories, indicating a year earlier than the one of
upload on AO3. Since we are using AO3 as a data source to study cultural accumulation in fan
ifction, we want to consider the backdated year as the original date of these stories. With this
procedure, the first year with more than 100 stories is the year 2002 (324 stories). We fixed this
minimum threshold in order to group the stories in percentiles (see below). Overall, it should
be kept in mind that data from earlier than 2010 are less representative of the Harry Potter fan
ifction compared to later years, since only a portion of the stories published elsewhere has been
imported. Moreover, this date adjustment can be used only for the accumulation analysis, but
not for the improvement analysis, since hits and kudos started to accumulate only from the
date of publication on AO3.</p>
      <sec id="sec-2-1">
        <title>2.1. Accumulation</title>
        <p>In order to have accumulation, the number of cultural traits at time t+1 should be higher
than the number of cultural traits at time t. The hypothesis we test in our dataset is that
2010
Year
the number of unique tags increases in time. We first test this hypothesis on the overall
number of diferent tags, i.e. if the overall Harry Potter fandom accumulates traits (more
characters, more relationships, more themes). Since the overall accumulation is associated to
the parallel increase in the total number of stories (see Figure 1), we also check the average
number of unique tags per story, i.e. if single stories accumulate traits (more characters, more
relationships, more themes per story).</p>
        <p>For the latter analysis, we confront stories with a similar popularity (defined by the number
of kudos received) relative to the year in which they are published. There are two reasons
for doing this. First, our cumulative culture hypothesis does not predict necessarily that all
stories should increase the number of traits, only that the ”best” recent stories should have
more traits than the ”best” earlier stories. Given the increase in the total number of stories,
it could be that this efect is hidden when averaging on the total number of stories. Second,
adding more tags can be a way to make a story more discoverable by readers with diferent
interests and consequently increase the number of hits and the probability to receive kudos, so
it makes sense to compare stories with similar popularity through years. To do this, we group
the stories of each year in diferent percentiles according to the number of kudos and analyse
the trend of the number of unique tags for the first, middle, and last decile.</p>
      </sec>
      <sec id="sec-2-2">
        <title>2.2. Improvement</title>
        <p>There is improvement when the cultural traits at time t+1 are ”better” (more efective
according to some measure) than the cultural trait at time t. The hypothesis we test in our dataset
is that the appreciation of stories increases in time, i.e. stories receive more hits and kudos.</p>
        <p>As we did for accumulation, we analyse both the global trend and the trend for single
stories. A further issue concerns the choice of a reliable measure for stories’ appreciation. For
the analysis of global trend, we use three measures. The absolute number of kudos is simply
the total sum of kudos received. This measure may favour very popular but less appreciated,
characters
freeforms</p>
        <p>relationships
60000
40000
20000
0
9000
6000
3000
0
2002
2006
2010
2014
2018
2002
2006
2014
2018
2002
2006
2010
2014</p>
        <p>2018
in proportion, stories, and also favour older stories that have had more time to accumulate
kudos. We thus use an additional second measure: the kudos/hits ratio. The ratio accounts
for the age of a story, but it may favour ”niche” stories, with very few hits and kudos. For this
reasons, we finally consider a weighted measure, an engagement score S computed as the true
Bayesian average [4, 6] of the kudos/hits ratio, calculated as:</p>
        <p>S = wK + (1 − w) ∗ Kav
where K is the kudos/hits ratio of the story, Kav is the average of the ratio in a certain year,
and w is a weighting parameter, calculated as:
w =</p>
        <p>H</p>
        <p>H + Hav
where H is the number of hits for a certain story, and Hav is the average number of hits per
story for a certain year.</p>
        <p>For single stories, we only compute the engagement score S, for the first, middle, and last
decile.</p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>3. Results</title>
      <sec id="sec-3-1">
        <title>3.1. Accumulation</title>
        <p>3.0
2.5
2.0
1.5
1.0
2002
2006</p>
        <p>Looking at the average number of unique tags per story, Figure 4 shows that they also
increase in time. This is true for stories with all levels of popularity/quality, as can be seen
from the accumulation slopes of Figure 4, which are always positive from 2002 to 2019 for all
three samples (low, mid, and high percentiles). However, the best stories (higher percentiles)
have a faster pace of accumulation, as predicted by the cumulative culture hypothesis.</p>
      </sec>
      <sec id="sec-3-2">
        <title>3.2. Improvement</title>
        <p>●●●●●●●●●●
●●●●●●●●●●
●●●●●
●●●●●●●●●
●
●
●
●●●●●●●●●
●●●●●
●●●●●●●●●
●
●
●
●
2014
Year
●●●●●●●●●●
●●●●●
●●●●●●●●●
●
●●●●●●●●●
●●●●●
●●●●●●●●●
●
●
●
●
●●●●●●●●●
●●●●●
●●●●●●●●●
●
2014Year
2012
2016
2018
weighted
2010
2012
2014
2016
2018
2010
2012
2016
2018
2012
2014
2016
2018</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4. Discussion</title>
      <p>The results of our work in progress show that we can observe two features of cumulative culture,
namely accumulation and improvement, in online fan fiction. Interestingly, the two features
can be detected both at the global level, i.e. considering all stories, and when analysing single
stories. While the former observation is expected, as matched by the parallel increase in the
number of stories, the latter is more surprising, suggesting that individual stories became,
through years, more complex and more appreciated by readers.</p>
      <p>In future works, to provide a complete picture of cumulative culture in this domain, we plan
to also analyse the ”ratcheting” feature, that is, the fact that novel innovations draw on past
ones. In our case, this would imply to detect, for example, that new introduced tags tend to
appear in correspondence of specific previous tags, e.g. ”Alternate Universe - Modern Setting”
with ”Alternate Universe - Canon Divergence”.</p>
      <p>In this research, and in the planned research on ratcheting, we focused on tags. The analysis
of tags’ frequency can be combined with techniques like text re-use detection and stylometry, to
check whether older stories contain sentences that are ”copied” or adapted in more recent stories
(word frequency patterns), or to check text similarities concerning themes (topic modelling).
Similarly, accumulation, or an increase in complexity, could be detected at the more
finegrained level of textual properties.</p>
      <p>We are not aware of similar research for fiction published by institutionalized authors and
publishers, but it would be interesting to compare cumulative cultural evolution in two similar
domains, one which is supported by digital online media and one which is not. As discussed
in the Introduction, an important research question is whether particular features of online
digital media—increased fidelity and availability—support cultural accumulation.</p>
      <p>Another aspect that would be interesting to take into account is the efect on fanfiction of the
publication of further instalments of the original work (e.g. new books or films). An efect has
been documented for fanfiction related to various fandoms, but not all of them [ 7]. For Harry
Potter, for example, the release of the spin-of ”Fantastic Beasts and Where to Find Them” in
November 2016 increased the number of published stories in 2016 and 2017. However, on AO3
there was no such efect with the release of the last two films of the original series ”Harry Potter
and the Deathly Hallows” part 1 and part 2, in November 2010 and July 2011 respectively,
because at the time a lot of Harry Potter fanfiction was being posted on Fanfiction.net, which
indeed saw a huge increase in posting in those months [7].</p>
      <p>More generally, we believe cultural evolution provides a fruitful theoretical background for
digital literary studies, introducing a new range of testable hypotheses that can elucidate some
of the dynamics studied by digital humanities. On the other hand, digital texts (and the
sophisticated methodologies developed in literary studies and Natural Language Processing to
analyse them) are an interesting and increasingly data-rich domain for cultural evolutionists.
We hope our research will contribute to the further exploration of this interdisciplinary space.</p>
    </sec>
    <sec id="sec-5">
      <title>Acknowledgments</title>
      <p>Thanks to finnagain, destinationtoast, Shay Guy, and the other fans who publicly shared
their statistics about fanfiction.
[4] J. Balraj and C. Farook. “Enhance Rating Algorithm for Restaurants”. en. In: Advances
in Information and Communication. Ed. by K. Arai and R. Bhatia. Cham: Springer,
2020, pp. 224–234. isbn: 978-3-030-12384-0 978-3-030-12385-7. doi:
10.1007/978-3-03012385-7_18. (Visited on 07/16/2020).
[6] ebc. How to Rank (Restaurants). en-US. Jan. 2015. url: http://www.ebc.cat/2015/01
/05/how-to-rank-restaurants/ (visited on 07/16/2020).
[7] S. Guy. FANFICTION.NET: FANDOMS OVER TIME. Feb. 2015. url: https://toas
tystats.tumblr.com/post/111930409603/fanfictionnet- fandoms- over- time- toasty- says
(visited on 09/09/2020).
[14] F. Pianzola. fedormyskin/Linked-Potter. en. 2020. url: https://github.com/fedormyski
n/Linked-Potter (visited on 09/09/2020).</p>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          [1]
          <string-name>
            <given-names>A.</given-names>
            <surname>Acerbi</surname>
          </string-name>
          .
          <article-title>Cultural Evolution in the Digital Age</article-title>
          . Oxford, New York: Oxford University Press, Dec.
          <year>2019</year>
          . isbn:
          <fpage>978</fpage>
          -0-
          <fpage>19</fpage>
          -883594-3.
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          [2]
          <string-name>
            <given-names>A.</given-names>
            <surname>Acerbi</surname>
          </string-name>
          and
          <string-name>
            <given-names>A.</given-names>
            <surname>Mesoudi</surname>
          </string-name>
          . “
          <article-title>If we are all cultural Darwinians what's the fuss about? Clarifying recent disagreements in the field of cultural evolution”. en</article-title>
          .
          <source>In: Biology &amp; Philosophy 30.4</source>
          (
          <issue>2015</issue>
          ), pp.
          <fpage>481</fpage>
          -
          <lpage>503</lpage>
          . issn:
          <fpage>1572</fpage>
          -
          <lpage>8404</lpage>
          . doi:
          <volume>10</volume>
          .1007/s10539-015-9490-2. (Visited on 11/21/
          <year>2019</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          [3]
          <string-name>
            <given-names>C.</given-names>
            <surname>Aragon</surname>
          </string-name>
          ,
          <string-name>
            <given-names>K.</given-names>
            <surname>Davis</surname>
          </string-name>
          , and
          <string-name>
            <given-names>C.</given-names>
            <surname>Fiesler</surname>
          </string-name>
          .
          <article-title>Writers in the Secret Garden: Fanfiction, Youth, and New Forms of Mentoring</article-title>
          . English. Cambridge: MIT Press,
          <year>2019</year>
          . isbn:
          <fpage>978</fpage>
          -0-
          <fpage>262</fpage>
          - 53780-3.
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          [8]
          <string-name>
            <given-names>J.</given-names>
            <surname>Henrich</surname>
          </string-name>
          . “
          <article-title>Demography and Cultural Evolution: How Adaptive Cultural Processes can Produce Maladaptive Losses: The Tasmanian Case”</article-title>
          .
          <source>In: American Antiquity 69.2</source>
          (
          <issue>2004</issue>
          ), pp.
          <fpage>197</fpage>
          -
          <lpage>214</lpage>
          . issn:
          <fpage>0002</fpage>
          -
          <lpage>7316</lpage>
          . doi:
          <volume>10</volume>
          .2307/4128416. (Visited on 12/02/
          <year>2019</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          [9]
          <string-name>
            <given-names>J.</given-names>
            <surname>Henrich</surname>
          </string-name>
          .
          <article-title>The Secret of Our Success: How Culture Is Driving Human Evolution, Domesticating Our Species, and Making Us Smarter</article-title>
          . English. Princeton &amp; Oxford: Princeton University Press, Oct.
          <year>2015</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          [10]
          <string-name>
            <given-names>B.</given-names>
            <surname>McHale</surname>
          </string-name>
          .
          <source>Postmodernist Fiction. en. London: Methuen</source>
          ,
          <year>1987</year>
          . isbn:
          <fpage>978</fpage>
          -0-
          <fpage>203</fpage>
          -39332-1.
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          [11]
          <string-name>
            <given-names>A.</given-names>
            <surname>Mesoudi</surname>
          </string-name>
          and
          <string-name>
            <given-names>A.</given-names>
            <surname>Thornton</surname>
          </string-name>
          . “
          <article-title>What is cumulative cultural evolution?”</article-title>
          <source>In: Proceedings of the Royal Society B: Biological Sciences 285.1880 (June</source>
          <year>2018</year>
          ), p.
          <fpage>20180712</fpage>
          . doi:
          <volume>10</volume>
          .1098/rspb.
          <year>2018</year>
          .
          <volume>0712</volume>
          . (Visited on 11/22/
          <year>2019</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          [12]
          <string-name>
            <given-names>F.</given-names>
            <surname>Moretti</surname>
          </string-name>
          . “
          <article-title>The Slaughterhouse of Literature”. en</article-title>
          .
          <source>In: Modern Language Quarterly</source>
          <volume>61</volume>
          .1 (
          <issue>Mar</issue>
          .
          <year>2000</year>
          ), pp.
          <fpage>207</fpage>
          -
          <lpage>228</lpage>
          . issn:
          <fpage>0026</fpage>
          -
          <lpage>7929</lpage>
          ,
          <fpage>1527</fpage>
          -
          <lpage>1943</lpage>
          . doi:
          <volume>10</volume>
          .1215/
          <fpage>00267929</fpage>
          -61-1-
          <lpage>207</lpage>
          . (Visited on 09/08/
          <year>2020</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          [13]
          <string-name>
            <given-names>O.</given-names>
            <surname>Morin</surname>
          </string-name>
          .
          <article-title>How Traditions Live and Die</article-title>
          . English. London &amp; New York: Oxford University Press, Nov.
          <year>2015</year>
          . isbn:
          <fpage>978</fpage>
          -0-
          <fpage>19</fpage>
          -021050-2.
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          [15]
          <string-name>
            <given-names>J.</given-names>
            <surname>Porter</surname>
          </string-name>
          .
          <source>Popularity/Prestige. Tech. rep. 17</source>
          . Stanford Literary Lab, Sept.
          <year>2018</year>
          . url: https://litlab.stanford.edu/LiteraryLabPamphlet17.pdf (visited on 09/29/
          <year>2018</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          [16]
          <string-name>
            <given-names>O.</given-names>
            <surname>Sobchuk</surname>
          </string-name>
          and
          <string-name>
            <given-names>P.</given-names>
            <surname>Tinits</surname>
          </string-name>
          . “
          <article-title>Cultural Attraction in Film Evolution: the Case of Anachronies”. en</article-title>
          .
          <source>In: Journal of Cognition and Culture</source>
          <volume>20</volume>
          .
          <fpage>3</fpage>
          -
          <lpage>4</lpage>
          (
          <issue>Aug</issue>
          .
          <year>2020</year>
          ), pp.
          <fpage>218</fpage>
          -
          <lpage>237</lpage>
          . issn:
          <fpage>1568</fpage>
          -
          <lpage>5373</lpage>
          ,
          <fpage>1567</fpage>
          -
          <lpage>7095</lpage>
          . doi:
          <volume>10</volume>
          .1163/
          <fpage>15685373</fpage>
          -
          <lpage>12340082</lpage>
          . (Visited on 09/08/
          <year>2020</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          [17]
          <string-name>
            <surname>A. G. Stacey.</surname>
          </string-name>
          “
          <article-title>Robust parameterisation of ages of references in published research”. en</article-title>
          .
          <source>In: Journal of Informetrics 14.3</source>
          (
          <issue>Aug</issue>
          .
          <year>2020</year>
          ). issn:
          <volume>17511577</volume>
          . doi:
          <volume>10</volume>
          .1016/j.joi.
          <year>2020</year>
          .
          <volume>10</volume>
          1048. (Visited on 06/26/
          <year>2020</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>
          [18]
          <string-name>
            <surname>J. M. Stubbersfield</surname>
            ,
            <given-names>E. G.</given-names>
          </string-name>
          <string-name>
            <surname>Flynn</surname>
            , and
            <given-names>J. J.</given-names>
          </string-name>
          <string-name>
            <surname>Tehrani</surname>
          </string-name>
          . “
          <article-title>Cognitive Evolution and the Transmission of Popular Narratives: A Literature Review and Application to Urban Legends”</article-title>
          .
          <source>In: Evolutionary Studies in Imaginative Culture 1.1</source>
          (
          <issue>2017</issue>
          ), pp.
          <fpage>121</fpage>
          -
          <lpage>136</lpage>
          . issn:
          <volume>24729884</volume>
          , 24729876. doi:
          <volume>10</volume>
          .26613/esic.1.1.20.
        </mixed-citation>
      </ref>
      <ref id="ref14">
        <mixed-citation>
          [19]
          <string-name>
            <given-names>P.</given-names>
            <surname>Tinits</surname>
          </string-name>
          and
          <string-name>
            <given-names>O.</given-names>
            <surname>Sobchuk</surname>
          </string-name>
          . “
          <article-title>Open-ended cumulative cultural evolution of Hollywood film crews”. en</article-title>
          .
          <source>In: Evolutionary Human Sciences</source>
          <volume>2</volume>
          (
          <year>2020</year>
          ). issn:
          <fpage>2513</fpage>
          -
          <lpage>843X</lpage>
          . doi:
          <volume>10</volume>
          .1017/e hs.
          <year>2020</year>
          .
          <volume>21</volume>
          . (Visited on 07/09/
          <year>2020</year>
          ).
        </mixed-citation>
      </ref>
      <ref id="ref15">
        <mixed-citation>
          <string-name>
            <given-names>K.</given-names>
            <surname>Vaesen</surname>
          </string-name>
          et al. “
          <article-title>Population size does not explain past changes in cultural complexity”. eng</article-title>
          .
          <source>In: Proceedings of the National Academy of Sciences of the United States of America 113.16 (Apr</source>
          .
          <year>2016</year>
          ),
          <fpage>E2241</fpage>
          -
          <lpage>2247</lpage>
          . issn:
          <fpage>1091</fpage>
          -
          <lpage>6490</lpage>
          . doi:
          <volume>10</volume>
          .1073/pnas.1520288113.
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>