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<front>
<journal-meta>
<journal-id journal-id-type="publisher-id">Front. Psychol.</journal-id>
<journal-title>Frontiers in Psychology</journal-title>
<abbrev-journal-title abbrev-type="pubmed">Front. Psychol.</abbrev-journal-title>
<issn pub-type="epub">1664-1078</issn>
<publisher>
<publisher-name>Frontiers Media S.A.</publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.3389/fpsyg.2018.02321</article-id>
<article-categories>
<subj-group subj-group-type="heading">
<subject>Psychology</subject>
<subj-group>
<subject>General Commentary</subject>
</subj-group>
</subj-group>
</article-categories>
<title-group>
<article-title>Commentary: The Attraction Effect in Decision Making: Superior Performance by Older Adults</article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author" corresp="yes">
<name><surname>Koscielniak</surname> <given-names>Maciej</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="aff" rid="aff2"><sup>2</sup></xref>
<xref ref-type="corresp" rid="c001"><sup>&#x0002A;</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/308212/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Rydzewska</surname> <given-names>Klara</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/345102/overview"/>
</contrib>
<contrib contrib-type="author">
<name><surname>Sedek</surname> <given-names>Grzegorz</given-names></name>
<xref ref-type="aff" rid="aff1"><sup>1</sup></xref>
<xref ref-type="aff" rid="aff3"><sup>3</sup></xref>
<uri xlink:href="http://loop.frontiersin.org/people/226816/overview"/>
</contrib>
</contrib-group>
<aff id="aff1"><sup>1</sup><institution>Interdisciplinary Center for Applied Cognitive Studies</institution>, <addr-line>Warsaw</addr-line>, <country>Poland</country></aff>
<aff id="aff2"><sup>2</sup><institution>Faculty in Poznan, SWPS University of Social Sciences and Humanities</institution>, <addr-line>Pozna&#x00144;</addr-line>, <country>Poland</country></aff>
<aff id="aff3"><sup>3</sup><institution>Department of Psychology, SWPS University of Social Sciences and Humanities</institution>, <addr-line>Warsaw</addr-line>, <country>Poland</country></aff>
<author-notes>
<fn fn-type="edited-by"><p>Edited by: Ulrich Hoffrage, Universit&#x000E9; de Lausanne, Switzerland</p></fn>
<fn fn-type="edited-by"><p>Reviewed by: Alexia Gaudeul, Georg-August-Universit&#x000E4;t G&#x000F6;ttingen, Germany; William Hedgcock, University of Minnesota Twin Cities, United States</p></fn>
<corresp id="c001">&#x0002A;Correspondence: Maciej Koscielniak <email>mkoscielniak&#x00040;swps.edu.pl</email></corresp>
<fn fn-type="other" id="fn001"><p>This article was submitted to Cognition, a section of the journal Frontiers in Psychology</p></fn></author-notes>
<pub-date pub-type="epub">
<day>22</day>
<month>11</month>
<year>2018</year>
</pub-date>
<pub-date pub-type="collection">
<year>2018</year>
</pub-date>
<volume>9</volume>
<elocation-id>2321</elocation-id>
<history>
<date date-type="received">
<day>27</day>
<month>07</month>
<year>2018</year>
</date>
<date date-type="accepted">
<day>06</day>
<month>11</month>
<year>2018</year>
</date>
</history>
<permissions>
<copyright-statement>Copyright &#x000A9; 2018 Koscielniak, Rydzewska and Sedek.</copyright-statement>
<copyright-year>2018</copyright-year>
<copyright-holder>Koscielniak, Rydzewska and Sedek</copyright-holder>
<license xlink:href="http://creativecommons.org/licenses/by/4.0/"><p>This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.</p></license>
</permissions>
<related-article id="RA1" related-article-type="commentary-article" journal-id="Front Psychol" journal-id-type="nlm-ta" vol="58" page="120" xlink:href="10.1080/02724980443000160" ext-link-type="doi">A Commentary on <article-title>The Attraction Effect in Decision Making: Superior Performance</article-title> by Older Adults by Kim, S., and Hasher, L. (2005). Q. J. Exp. Psychol. A 58, 120&#x02013;133. doi: <object-id>10.1080/02724980443000160</object-id></related-article> 
<kwd-group>
<kwd>aging</kwd>
<kwd>attraction effect</kwd>
<kwd>decoy effect</kwd>
<kwd>asymmetric dominance</kwd>
<kwd>decision making</kwd>
</kwd-group>
<contract-sponsor id="cn001">Narodowe Centrum Nauki<named-content content-type="fundref-id">10.13039/501100004281</named-content></contract-sponsor>
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<fig-count count="0"/>
<table-count count="0"/>
<equation-count count="0"/>
<ref-count count="19"/>
<page-count count="3"/>
<word-count count="1841"/>
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</article-meta>
</front>
<body>
<p>Older adults are stereotypically perceived as more susceptible to various scams and manipulations (Cuddy et al., <xref ref-type="bibr" rid="B4">2005</xref>). However, this hardly finds confirmation in scientific literature, where older citizens are often portrayed as very resistant to social and consumer influence. In some areas they even outperform their younger counterparts and preserve high effectiveness in decision-making until late adulthood (Yoon and Lee, <xref ref-type="bibr" rid="B18">2004</xref>; Ross et al., <xref ref-type="bibr" rid="B11">2014</xref>; Berg, <xref ref-type="bibr" rid="B2">2015</xref>).</p>
<p>One of the examples of common consumer manipulation is the <italic>attraction effect</italic> (also known as the <italic>decoy effect</italic> or <italic>asymmetric dominance effect</italic>; Huber et al., <xref ref-type="bibr" rid="B6">1982</xref>). It describes the case of preference reversals induced by the introduction of a decoy (inferior) option to a set of original alternatives. As a result, the dominating alternative (similar to the decoy but noticeably better) attracts attention and its popularity increases. This phenomenon has often been conceived as an example of irrationality in human choices and a clear violation of utility theory (von Neumann and Morgenstern, <xref ref-type="bibr" rid="B17">1944</xref>) (according to which preferences should be independent of irrelevant options; Luce, <xref ref-type="bibr" rid="B9">1959</xref>).</p>
<p>The attraction effect is not only associated with people&#x00027;s economic choices, but also with a wide range of social decisions and judgements (Trueblood et al., <xref ref-type="bibr" rid="B16">2013</xref>). The effect can be observed as soon as children start to appreciate the relative values of alternatives (at around age 5; Zhen and Yu, <xref ref-type="bibr" rid="B19">2016</xref>); but little is known about its effectiveness in late adulthood. There are only two papers investigating this topic (Tentori et al., <xref ref-type="bibr" rid="B15">2001</xref>; Kim and Hasher, <xref ref-type="bibr" rid="B8">2005</xref>)&#x02014;both suggesting that older adults are less prone to be victims of manipulation based on the presence of dominated options.</p>
<p>The value of those articles is unquestionable, as they give a solid rationale to confront popular and harmful stereotypes about aging. The aim of this commentary is not to undermine those results, but to suggest an alternative explanation for the observed lifetime changes in susceptibility to the attraction effect. Our elucidation may also be helpful in understanding why the effect of age on the attraction effect is strong in some studies, but insignificant in others.</p>
<p>Tentori et al. (<xref ref-type="bibr" rid="B15">2001</xref>) explain the results of their experiment in terms of the prudency and rationality of older adults, who deliberately exclude unfavorable options from their choice (in contrast to younger adults). Kim and Hasher (<xref ref-type="bibr" rid="B8">2005</xref>) expands this by focusing on the role of life-experience, reliance on different processing styles, and Damasio&#x00027;s somatic markers. All of these explanations may actually play an important role in the susceptibility to the attraction effect in late adulthood. However, we believe that they should be extended by lifetime changes in fluid competences and in epistemic motivation, which are crucial for most types of decision making in elderly adults.</p>
<p>It is empirically confirmed that adults experience monotonic decrease in basic cognitive abilities (incl. mental speed, working memory capacity, etc.) throughout their life (Salthouse, <xref ref-type="bibr" rid="B12">2012</xref>; Sedek et al., <xref ref-type="bibr" rid="B13">2013</xref>). The engagement in demanding mental processes is related to increasing cognitive costs (Hess, <xref ref-type="bibr" rid="B5">2014</xref>), so older adults become very selective in choosing tasks in which they want to invest their limited resources (Baltes and Baltes, <xref ref-type="bibr" rid="B1">1990</xref>). We strongly believe that this mechanism is important for analyzing the susceptibility to the attraction effect in older adults, who may avoid engaging in hypothetical scenarios used in laboratory settings.</p>
<p>We predict that older adults may not be able to notice the character of the dominating relation, which makes them resistant to the attraction effect. This hypothesis is fully consistent with the recent theoretical model of Crosetto and Gaudeul (<xref ref-type="bibr" rid="B3">2014</xref>), who claims that there are two necessary steps for this effect to occur: to perceive the comparable similarity between the dominant option and the decoy; and to notice the dominant relation between them (leading to the exclusion of decoy). We suggest that due to the mentioned cognitive and motivational limitations, older adults may not be able to satisfy at least one of these conditions when the attributes are complex and mentally demanding.</p>
<p>In the <xref ref-type="supplementary-material" rid="SM1">Supplementary Materials</xref> we analyze the relationship between age and the number of decoys chosen in the commented article (as an indicator of the inability to notice the dominant relation in the choice set). The Chi-Squared Tests of Independence show that older adults choose the decoys more frequently (in comparison to dominating option choices) only in the grocery task (where only young adults showed the attraction effect), while no such relationship is confirmed for extra-credit task (no attraction effect in both age groups).</p>
<p>Our explanation portrays the paradoxically positive impact of cognitive deficits on decision-making quality in late adulthood. Older adults may be protected from complex context manipulations due to cognitive declines and their unwillingness to invest cognitive resources in effortful decision processes. This is a promising starting point for further studies on lifetime changes in susceptibility to the attraction effect and other context effects. We expect that those changes will be especially distinct for decisions requiring certain amount of deliberation, but will not be significant for tasks described by simple, perceptual attributes (or demanding experience-based knowledge). In the domains of automatic and intuitive decision-making there are no lifetime competence declines (Mikels et al., <xref ref-type="bibr" rid="B10">2010</xref>), so the decoy alternative should be perceived similarly by younger and older adults.</p>
<p>To conclude, the proposed explanation of lifetime changes in susceptibility to the attraction effect refers to cognitive and motivational changes in late adulthood (Hess, <xref ref-type="bibr" rid="B5">2014</xref>) and to dual system theories (Stanovich and West, <xref ref-type="bibr" rid="B14">2000</xref>; Kahneman, <xref ref-type="bibr" rid="B7">2003</xref>). We expect that for decisions based on deliberative stimuli (requiring numeric or quality information processing) older adults will be more resistant to context manipulations compared to younger adults&#x02014;as described by Tentori et al. (<xref ref-type="bibr" rid="B15">2001</xref>) and partially by Kim and Hasher (<xref ref-type="bibr" rid="B8">2005</xref>). However, for the choices described by System 1 attributes [intuitive or relying on visual perception, as in the study of Trueblood et al. (<xref ref-type="bibr" rid="B16">2013</xref>)] we expect to observe no differences. This hypothesis suggests that stereotypically perceived weaknesses of late adulthood (cognitive declines) can also act as compensatory mechanisms in specific situations, leading to more successful decision-making.</p>
<sec id="s1">
<title>Author contributions</title>
<p>All authors listed have made a substantial, direct and intellectual contribution to the work, and approved it for publication.</p>
<sec>
<title>Conflict of interest statement</title>
<p>The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.</p>
</sec>
</sec>
</body>
<back>
<sec sec-type="supplementary-material" id="s2">
<title>Supplementary material</title>
<p>The Supplementary Material for this article can be found online at: <ext-link ext-link-type="uri" xlink:href="https://www.frontiersin.org/articles/10.3389/fpsyg.2018.02321/full#supplementary-material">https://www.frontiersin.org/articles/10.3389/fpsyg.2018.02321/full#supplementary-material</ext-link></p>
<supplementary-material xlink:href="Table_1.docx" id="SM1" mimetype="application/vnd.openxmlformats-officedocument.wordprocessingml.document" xmlns:xlink="http://www.w3.org/1999/xlink"/>
</sec>
<ref-list>
<title>References</title>
<ref id="B1">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Baltes</surname> <given-names>P. B.</given-names></name> <name><surname>Baltes</surname> <given-names>M. M.</given-names></name></person-group> (Eds.). (<year>1990</year>). <article-title>Psychological perspectives on successful aging: The model of selective optimization with compensation</article-title> in <source>Successful Aging: Perspectives from the Behavioral Sciences</source>, (<publisher-loc>New York, NY</publisher-loc>: <publisher-name>Cambridge University Press</publisher-name>), <fpage>1</fpage>&#x02013;<lpage>34</lpage>.</citation></ref>
<ref id="B2">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Berg</surname> <given-names>L.</given-names></name></person-group> (<year>2015</year>). <article-title>Consumer vulnerability: are older people more vulnerable as consumers than others?</article-title> <source>Int. J. Consum. Stud.</source> <volume>39</volume>, <fpage>284</fpage>&#x02013;<lpage>293</lpage>. <pub-id pub-id-type="doi">10.1111/ijcs.12182</pub-id></citation></ref>
<ref id="B3">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Crosetto</surname> <given-names>P.</given-names></name> <name><surname>Gaudeul</surname> <given-names>A.</given-names></name></person-group> (<year>2014</year>). <source>Testing the Strength and Robustness of the Attraction Effect in Consumer Decision Making</source>. Working Papers. Grenoble Applied Economics Laboratory (GAEL).</citation></ref>
<ref id="B4">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Cuddy</surname> <given-names>A. J.</given-names></name> <name><surname>Norton</surname> <given-names>M. I.</given-names></name> <name><surname>Fiske</surname> <given-names>S. T.</given-names></name></person-group> (<year>2005</year>). <article-title>This old stereotype: the stubbornness and pervasiveness of the elderly stereotype</article-title>. <source>J. Soc. Issues</source> <volume>61</volume>, <fpage>267</fpage>&#x02013;<lpage>285</lpage>. <pub-id pub-id-type="doi">10.1111/j.1540-4650.2005.00405</pub-id></citation></ref>
<ref id="B5">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Hess</surname> <given-names>T.</given-names></name></person-group> (<year>2014</year>). <article-title>Selective engagement of cognitive resources: motivational influences on older adults&#x00027; cognitive functioning</article-title>. <source>Perspect. Psychol. Sci.</source> <volume>9</volume>, <fpage>388</fpage>&#x02013;<lpage>407</lpage>. <pub-id pub-id-type="doi">10.1177/1745691614527465</pub-id><pub-id pub-id-type="pmid">26173272</pub-id></citation></ref>
<ref id="B6">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Huber</surname> <given-names>J.</given-names></name> <name><surname>Payne</surname> <given-names>J. W.</given-names></name> <name><surname>Puto</surname> <given-names>C.</given-names></name></person-group> (<year>1982</year>). <article-title>Adding asymmetrically dominated alternatives: violations of regularity and the similarity hypothesis</article-title>. <source>J. Consum. Res.</source> <volume>9</volume>:<fpage>90</fpage>. <pub-id pub-id-type="doi">10.1086/208899</pub-id></citation></ref>
<ref id="B7">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Kahneman</surname> <given-names>D.</given-names></name></person-group> (<year>2003</year>). <article-title>A perspective on judgment and choice: mapping bounded rationality</article-title>. <source>Am. Psychol.</source> <volume>58</volume>, <fpage>697</fpage>&#x02013;<lpage>720</lpage>. <pub-id pub-id-type="doi">10.1037/0003-066X.58.9.697</pub-id><pub-id pub-id-type="pmid">14584987</pub-id></citation></ref>
<ref id="B8">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Kim</surname> <given-names>S.</given-names></name> <name><surname>Hasher</surname> <given-names>L.</given-names></name></person-group> (<year>2005</year>). <article-title>The attraction effect in decision making: superior performance by older adults</article-title>. <source>Q. J. Exp. Psychol. A</source> <volume>58</volume>, <fpage>120</fpage>&#x02013;<lpage>133</lpage>. <pub-id pub-id-type="doi">10.1080/02724980443000160</pub-id><pub-id pub-id-type="pmid">15881294</pub-id></citation></ref>
<ref id="B9">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Luce</surname> <given-names>R. D.</given-names></name></person-group> (<year>1959</year>). <source>Individual Choice Behavior: A Theoretical Analysis</source>. <publisher-loc>New York, NY</publisher-loc>: <publisher-name>Wiley</publisher-name>.</citation></ref>
<ref id="B10">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Mikels</surname> <given-names>J. A.</given-names></name> <name><surname>Lockenhoff</surname> <given-names>C. E.</given-names></name> <name><surname>Maglio</surname> <given-names>S. J.</given-names></name> <name><surname>Goldstein</surname> <given-names>M. K.</given-names></name> <name><surname>Garber</surname> <given-names>A.</given-names></name> <name><surname>Carstensen</surname> <given-names>L. L.</given-names></name></person-group> (<year>2010</year>). <article-title>Following your heart or your head: focusing on emotions versus information differentially influences the decisions of younger and older adults</article-title>. <source>J. Exp. Psychol. Appl.</source> <volume>16</volume>, <fpage>87</fpage>&#x02013;<lpage>95</lpage>. <pub-id pub-id-type="doi">10.1037/a0018500</pub-id><pub-id pub-id-type="pmid">20350046</pub-id></citation></ref>
<ref id="B11">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Ross</surname> <given-names>M.</given-names></name> <name><surname>Grossmann</surname> <given-names>I.</given-names></name> <name><surname>Schryer</surname> <given-names>E.</given-names></name></person-group> (<year>2014</year>). <article-title>Contrary to psychological and popular opinion, there is no compelling evidence that older adults are disproportionately victimized by consumer fraud</article-title>. <source>Persp. Psychol. Sci.</source> <volume>9</volume>, <fpage>427</fpage>&#x02013;<lpage>442</lpage>. <pub-id pub-id-type="doi">10.1177/1745691614535935</pub-id><pub-id pub-id-type="pmid">26173274</pub-id></citation></ref>
<ref id="B12">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Salthouse</surname> <given-names>T.</given-names></name></person-group> (<year>2012</year>). <article-title>Consequences of age-related cognitive decline</article-title>. <source>Annu. Rev. Psychol.</source> <volume>63</volume>, <fpage>201</fpage>&#x02013;<lpage>226</lpage>. <pub-id pub-id-type="doi">10.1146/annurev-psych-120710-100328</pub-id></citation></ref>
<ref id="B13">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Sedek</surname> <given-names>G.</given-names></name> <name><surname>Verhaeghen</surname> <given-names>P.</given-names></name> <name><surname>Martin</surname> <given-names>M.</given-names></name></person-group> (<year>2013</year>). <source>Social and Motivational Compensatory Mechanisms of Age-Related Cognitive Decline. Special Issue of Aging, Neuropsychology, and Cognition</source>. <publisher-loc>Hove</publisher-loc>: <publisher-name>Psychology Press</publisher-name>.</citation></ref>
<ref id="B14">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Stanovich</surname> <given-names>K. E.</given-names></name> <name><surname>West</surname> <given-names>R. F.</given-names></name></person-group> (<year>2000</year>). <article-title>Individual differences in reasoning: implications for the rationality debate?</article-title> <source>Behav. Brain Sci.</source> <volume>23</volume>, <fpage>645</fpage>&#x02013;<lpage>665</lpage>. <pub-id pub-id-type="doi">10.1017/CBO9780511808098.026</pub-id><pub-id pub-id-type="pmid">11301544</pub-id></citation></ref>
<ref id="B15">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Tentori</surname> <given-names>K.</given-names></name> <name><surname>Osherson</surname> <given-names>D.</given-names></name> <name><surname>Hasher</surname> <given-names>L.</given-names></name> <name><surname>May</surname> <given-names>C.</given-names></name></person-group> (<year>2001</year>). <article-title>Wisdom and aging: irrational preferences in college students but not older adults</article-title>. <source>Cognition</source> <volume>81</volume>, <fpage>B87</fpage>&#x02013;<lpage>B96</lpage>. <pub-id pub-id-type="doi">10.1016/S0010-0277(01)00137-8</pub-id></citation></ref>
<ref id="B16">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Trueblood</surname> <given-names>J. S.</given-names></name> <name><surname>Brown</surname> <given-names>S. D.</given-names></name> <name><surname>Heathcote</surname> <given-names>A.</given-names></name> <name><surname>Busemeyer</surname> <given-names>J. R.</given-names></name></person-group> (<year>2013</year>). <article-title>Not just for consumers: context effects are fundamental to decision making</article-title>. <source>Psychol. Sci.</source> <volume>24</volume>, <fpage>901</fpage>&#x02013;<lpage>908</lpage>. <pub-id pub-id-type="doi">10.1177/0956797612464241</pub-id><pub-id pub-id-type="pmid">23610134</pub-id></citation></ref>
<ref id="B17">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>von Neumann</surname> <given-names>J.</given-names></name> <name><surname>Morgenstern</surname> <given-names>O.</given-names></name></person-group> (<year>1944</year>). <source>Theory of Games and Economic Behavior</source>. <publisher-loc>Princeton, NJ</publisher-loc>: <publisher-name>Princeton University Press</publisher-name>.</citation></ref>
<ref id="B18">
<citation citation-type="book"><person-group person-group-type="author"><name><surname>Yoon</surname> <given-names>C.</given-names></name> <name><surname>Lee</surname> <given-names>M. P.</given-names></name></person-group> (<year>2004</year>). <source>Persuasion Implications of Age-related Differences in Consumer Processing: The Effects of Motivation and Ability</source>. Working title, <publisher-name>University of Michigan</publisher-name>.</citation></ref>
<ref id="B19">
<citation citation-type="journal"><person-group person-group-type="author"><name><surname>Zhen</surname> <given-names>S.</given-names></name> <name><surname>Yu</surname> <given-names>R.</given-names></name></person-group> (<year>2016</year>). <article-title>The development of the asymmetrically dominated decoy effect in young children</article-title>. <source>Sci. Rep.</source> <volume>6</volume>:<fpage>22678</fpage>. <pub-id pub-id-type="doi">10.1038/srep22678</pub-id><pub-id pub-id-type="pmid">26935899</pub-id></citation></ref>
</ref-list> 
<fn-group>
<fn fn-type="financial-disclosure"><p><bold>Funding.</bold> This work was supported by the National Science Centre, Poland, under Grant 2015/17/B/HS6/04185, awarded to GS.</p>
</fn>
</fn-group>
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</article> 