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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Deductive vs. Inductive Instructions: Evaluating the Predictive Powers of Cognitive Models for Conditional Reasoning</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Sara Todorovikj</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Marco Ragni</string-name>
          <email>ragni@informatik.uni-freiburg.de</email>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Cognitive Computation Lab, University of Freiburg</institution>
          ,
          <addr-line>79110 Freiburg</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Danish Institute for Advanced Study, University of Southern Denmark</institution>
        </aff>
      </contrib-group>
      <fpage>74</fpage>
      <lpage>87</lpage>
      <abstract>
        <p>Throughout the years, the question how humans reason with conditionals has been extensively researched by various disciplines due to its importance not only in science, but also our everyday life. A vast amount of cognitive models have been developed in order to get a better insight into how individuals interpret and reason with 'If'. Todorovikj and Ragni [21] proposed a predictive modeling testing paradigm for probabilistic conditional reasoning models. Instead of evaluating models based on their ability to fit aggregate data, the focus was shifted to the individual by challenging cognitive models to predict a participant's answer on a scale from 0 to 100. In this work, we continue the challenge of predicting probabilistic endorsements by taking data from Singmann and Klauer [19] who examine the influence of deductive vs. inductive instructions. We evaluate an established probabilistic cognitive model by Oaksford and Chater [11] and a proposed probabilistic approach based on mental models [21, 20]. Moreover, we take Oberauer's formalizations [12] of the Mental Model Theory [5] and the Suppositional Theory [4] and adapt them to represent probabilistic data in this new predictive testing paradigm. The models' parameter values are evaluated to examine their ability to represent the influence of instruction and content e↵ects.</p>
      </abstract>
      <kwd-group>
        <kwd>Conditional Reasoning</kwd>
        <kwd>Predictive Modeling</kwd>
        <kwd>Individuals</kwd>
        <kwd>Instruction E↵ect</kwd>
        <kwd>Content E↵ect</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        On a daily basis, we gather knowledge and information about ourselves and
our surroundings that we use to infer conclusions by processes of reasoning. For
many years, scientists work towards understanding how we reach these
conclusions and what cognitive processes lead to them. In the 60s, a deductive path
has been followed, assuming that logic is the basis for reasoning [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. However, it
has been repeatedly shown that humans are not always logical beings, the
content of a premise often makes us question its certainty in a way that standard
deductive logic cannot grasp [
        <xref ref-type="bibr" rid="ref19 ref8">19, 8</xref>
        ]. Acknowledging these uncertainties,
interpreting them as probabilities and switching the focus on the inductive strength
Copyright c 2021 for this paper by its authors. Use permitted under
Creative Commons License Attribution 4.0 International (CC BY 4.0).
of arguments creates a major shift leading to a new Bayesian paradigm [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ].
Proponents of both paradigms have developed a number of cognitive models and
experiments that represent and examine reasoning mechanisms corresponding to
the paradigm’s theories and assumptions. Singmann and Klauer [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] focus on the
conditional reasoning domain. Through two experiments they provide evidence
for a dissociation of the two reasoning modes: deductive and inductive and show
the need for theories to explicitly account for the e↵ect of instruction.
      </p>
      <p>Conditionals are statements of the form “If X then Y” (also written X ! Y,
where X is the antecedent and Y the consequent ) that often describe a causal
relationship between two propositions X and Y. Given a conditional (major premise)
and a state of a proposition (minor premise), a conclusion can be inferred about
the state of the other proposition. We consider the four major inference forms
modus ponens (MP), modus tollens (MT), arming the consequent (AC) and
denying the antecedent (DA), as shown in Table 1.</p>
      <p>
        In causal conditionals the necessity and suciency of X for Y can be
questioned and manipulated through two types of counterexamples: alternatives and
disablers. Alternatives enable Y to occur even if X hasn’t and decrease the
perceived necessity. On the other hand, disablers prevent Y from being true even if
X is, decreasing the perceived suciency. Conditionals whose content has many
alternatives but few disablers associated with it are called prological, ones with
few alternatives but many disablers are counterlogical, and if a conditional has
both many alternatives and disablers then it is called neutral [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ].
      </p>
      <p>
        In previous work [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ], we evaluated conditional models in a new predictive
evaluation setup, motivated by Riesterer et al.’s approach for syllogistic
reasoning [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ]. We showed that it is possible for models to predict a probabilistic
endorsement of a conclusion in the range 0-100, which is more challenging than
a dichotomous ‘yes’ or ‘no’ answer. The focus was to predict an individual’s
answer, increasing the diculty due to the varying subjective influence of disablers
and alternatives. Additionally we proposed a probabilistic approach based on
mental models, ✏-MMT, which showed to be a valuable competitor among other
Bayesian models.
      </p>
      <p>
        Our main goal is to once again challenge the predictive capabilities of
cognitive models, this time on Singman and Klauer’s data sets [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ]. We take
formalizations [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] of the Mental Model Theory [
        <xref ref-type="bibr" rid="ref18 ref5">5, 18</xref>
        ] and Suppositional Theory
[
        <xref ref-type="bibr" rid="ref4">4</xref>
        ], adapt them to represent probabilistic data and compare them to Oaksford
and Chater’s Bayesian model [
        <xref ref-type="bibr" rid="ref11 ref9">11, 9</xref>
        ] and ✏-MMT [
        <xref ref-type="bibr" rid="ref20 ref21">21, 20</xref>
        ]. Moreover, we will
analyze whether the models’ parameter values can account for the instruction and
content e↵ects.
2
      </p>
      <p>
        Data and Cognitive Models
We consider experimental data presented and analyzed by Singmann and Klauer
[
        <xref ref-type="bibr" rid="ref19">19</xref>
        ]. There are two experiments, Exp. 1 and Exp. 2, aiming to establish a
double dissociation between deductive and inductive instructions when validity and
plausibility of the conditional problems are pitted against each other.
      </p>
      <p>
        Under deductive instructions participants were asked to assume the truth of
the premises and disregard background knowledge when judging the conclusion’s
validity. Under inductive instructions, they were encouraged to use background
knowledge when judging the conclusion’s probability. In both experiments
participants were provided with prological and counterlogical conditionals.
Additionally, in Exp. 2 they were also given neutral conditionals. 40 participants
took part in Exp. 1, 20 received deductive instructions and 20 inductive. In Exp.
2, 27 participants received deductive instructions and 28 inductive, making it a
total of 55 participants. In both experiments, they provided endorsements in the
range 0-100 for the four inference forms for conditionals with everyday contents.
Table 2 shows content examples under deductive and inductive instructions.
The Mental Model Theory (MMT) assumes that when individuals are presented
with some information, they build a mental representation of it using mental
models. They aim to reach a conclusion based on the maintained information,
and often, individuals would engage in a search for counterexamples to the
conclusion. If their search is successful, they would no longer accept the conclusion
[
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]. A mental model consists of the truth states of the propositions in the premise.
Given a conditional premise “If X then Y”, the initial mental model that an
individual would construct is the one where both propositions are true, X Y.
      </p>
      <p>
        The MMT assumes that once the initial model is created it triggers the
recollection of relevant facts and knowledge [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. Those facts can either serve as
evidence that the initial model is correct or will stimulate a search for
alternatives and lead to extending the mental model representation in a second process.
The extended mental model representation is also called a fleshed-out
representation, as shown in Table 3. It contains models that describe cases where X is
false (written as ¬X). The fleshed-out representation consists of all the possible
combinations of truth-values for the propositions X and Y for which the
conditional “If X then Y” is true. Johnson-Laird and Byrne call representing only
what is true and not false the principle of truth [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. This coincides with the
material implication definition which is the leading interpretation of conditionals in
the deductive paradigm [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ].
      </p>
      <p>
        Later on we present and use a formalization of the MMT that is based on
equations provided by Schroyens et al. [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] who revise the theory as presented
by Johnson-Laird and Byrne [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ] and present an alternative model within the
mental models approach, focusing on the stage where individuals validate the
conclusion based on their mental model representation. They assume that when
looking for counterexamples individuals do not construct all possible alternative
models but rather aim for the model that would falsify the inference. Based
on the original model’s theory, when looking for counterexamples individuals
only test whether alternative models are consistent with the premises. Schroyens
et al. [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ] on the other hand, take background knowledge about the content
into consideration and suppose that counterexamples are retrieved from
longterm memory, which is where this theory stops being a theory of deductive
reasoning [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ]. With this modification the material implication interpretation of
conditionals within the theory is abandoned because now the X ¬Y model can
actually be retrieved from long-term memory and become a part of the mental
model representation. That leads to the possibility of refuting the logically valid
MP and MT inferences, which is a consequence of the presence of disablers as
described by the Suppression e↵ect [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ].
      </p>
      <p>
        Evans [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ] has criticized the MMT for its lack of directionality. Specifically,
comparing the di↵erences between reasoning problems involving “If X then Y”
and the ones involving “X only if Y”. Namely, people are more likely to draw
backward inferences (inferences from Y or ¬Y as a minor premise) in the “only
if” case and they are more likely to draw forward inferences (inferences from X or
¬X as a minor premise) in the case of “if...then”. Assuming a directionality from
the antecedent variable to the consequent variable, the only reachable conclusions
are the ones following that direction. For example, having only the model X Y
in the mental representation supports concluding Y from X (MP), but not X
from Y (AC).
2.2
      </p>
    </sec>
    <sec id="sec-2">
      <title>Suppositional Theory</title>
      <p>
        The Suppositional Theory assumes that two systems of reasoning are used in
order to make a conclusion for a given reasoning problem, called System 1 and
System 2. System 1 describes the heuristic or pragmatic inferences, whereas
System 2 is dedicated to abstract rule-based reasoning [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. The influence of each
system depends from one individual to another in terms of belief-based vs.
logicbased responses.
      </p>
      <p>
        Evans and Over [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] discuss early advancements towards the invalidity of the
material implication interpretation of indicative conditionals, as primarily done
by Ramsey [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ]. He suggests that when people reason about a conditional “If X
then Y”, they are judging the probability of Y, supposing X is true, i.e. P(Y|X),
widely known as The Ramsey Test, which leads to the individual’s degree of
belief in the conditional itself. Building up on this, System 1 is capable of only
generating conclusions that follow directly from an individual’s belief in the
conditional, leading to accepting only MP inferences, unless additional
conditional premises are added through pragmatic implicature and the MP inference
schemata is applied to them.
      </p>
      <p>
        System 2, on the other hand, can accept MT by a suppositional line of proof
[
        <xref ref-type="bibr" rid="ref12">12</xref>
        ]. The suppositional proof starts by supposing that X is true, which combined
with the given conditional rule, “If X then Y”, leads to the conclusion that Y is
true (MP inference). However, this contradicts the minor premise of MT, ¬Y,
therefore the supposition must be false, so ¬X must be true. This leads to the
acceptance of the MT inference form. Starting the suppositional proof with Y,
combined with the converse, “If Y then X” (assuming that the converse of the
conditional has been added by pragmatic implicature), leads to accepting the
DA inference form.
2.3
      </p>
    </sec>
    <sec id="sec-3">
      <title>Formalizations</title>
      <p>
        Oberauer [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] provides formalizations of the MMT and Suppositional Theory as
multinomial processing trees (MPTs). The MPT can be interpreted as a binary
decision diagram with parameters on the edges. In the case of MMT (Fig. 1),
the decisions are whether a human reasoner will add a mental model to their
representation. For the Suppositional Theory (Fig. 2), the parameters describe
the degree of belief in a conditional and/or its converses and inverses.
      </p>
      <p>The leafs represent combinations of inference forms that are accepted if that
specific path has been taken. It can be noted that there are combinations that
the theories cannot express. In our setup we are not interested in the acceptance,
but rather we aim to model individuals who provide probabilistic endorsements
in the range 0-100. Towards that goal, we derived expressions from the MPTs for
each inference form separately, by summing up and simplifying the probabilities
of all possible paths leading to accepting said inference form.</p>
      <p>
        For the MMT, Oberauer [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] presents three di↵erent formalization variants,
and two variants for the Suppositional Theory. For each theory, we focus only
on the variant that is best performing, so we adapted all five variants to model
probabilistic data, examined their predictive performance and picked the best
ones. In the following, we introduce the detailed technical background and
endorsement expression derivation solely for them.
      </p>
      <p>
        Mental Model Theory Formalizations Oberauer [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] presents three
formalization variants for the MMT: original, deductive and with directionality. The
best performing variant is MMT with Directionality.
      </p>
      <p>
        The original variant is built directly on equations provided by Schroyens et
al. [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ]. The deductive variant is a special case of the original one, where the
model X¬Y is impossible to be added to the mental representation.
      </p>
      <p>e
add
X¬Y
add
¬XY</p>
      <p>a
1 e
don’t add</p>
      <p>X¬Y
add
¬X¬Y</p>
      <p>f
1 a
add
X¬Y
e
don’t add
¬XY</p>
      <p>XY
1 e
don’t add</p>
      <p>X¬Y
r
1 f</p>
      <p>a
add
¬XY
e 1 e
add don’t add
X¬Y X¬Y</p>
      <p>X!Y
don’t add
¬X¬Y
add
X¬Y
1 a
e
don’t add
¬XY
1 r
1 e
don’t add</p>
      <p>X¬Y</p>
      <p>None
d 1 d d 1 d d 1 d
None reverse ¬reverse reverse ¬reverse reverse ¬reverse None
MP</p>
      <p>d 1 d d 1 d
reverse ¬reverse reverse ¬reverse
MP, MT MP</p>
      <p>AC, DA DA</p>
      <p>All 4 MP, DA</p>
      <p>AC</p>
      <p>None MP, AC MP
The parameters describe the probabilities of adding models to the representation.
r is the probability of adding the model X Y, f for the model ¬X¬Y, a for ¬X Y,
e for X ¬Y. Additionally, the parameter d describes the probability of reversing
the directionality.</p>
      <p>In total, MMT with Directionality needs five parameters to model one task.</p>
    </sec>
    <sec id="sec-4">
      <title>Suppositional Theory Formalizations Evans and Over [4] do not explicitly</title>
      <p>
        specify how the two systems interact, therefore Oberauer [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] provides two
variants – an Exclusive and a Sequential one. The best performing variant is the
Sequential one.
      </p>
      <p>The Exclusive variant assumes that either System 1 or System 2 is used
exclusively when reasoning.</p>
      <p>The Sequential variant (Fig. 2) assumes that the two systems work
sequentially. After the individual determines their degree of belief in the conditional
X!Y, System 1 takes over and has the possibility of adding the converse, Y!X,
and inverse, ¬X! ¬Y by pragmatic implicature. By combining the two, it can
arrive to the contraposition, ¬Y! ¬X. Once System 1 is done with adding
conditionals, it derives all the conclusions following from them. Next, System 2
takes the conditionals System 1 has added and with a certain probability and
applies the procedure for suppositional proof. Two di↵erent suppositional proofs
can take place. One supposes the truth of X and the original conditional and the
other supposes the truth of Y and the converse.</p>
      <p>We derived the following inference form endorsement expressions for
Suppositional Sequential based on the MPT, shown in Fig. 2:</p>
      <p>MP: b</p>
      <p>DA: b · (c · s⇤ · (1</p>
      <p>i) + i)
AC: b · c</p>
      <p>MT: b · ((1
s) · (2 · c · i
c2 · i2) + s)
The parameter b describes the belief in the conditional X!Y, c is the probability
of the converse to be added (Y!X) and i, the inverse (¬X! ¬Y). s is the
probability of the suppositional proof using X and the original conditional to
succeed and s⇤ for the proof using Y and the converse.</p>
      <p>In total, Suppositional Sequential needs five parameters to model one task.</p>
      <p>¬X! ¬Y
i + (1 i) · c
¬Y! ¬X
(1 c) · (1 i)
¬Y!no¬X
s 1 s
All 4 Supp. X no Supp. X
i</p>
      <p>Y!X</p>
      <p>c
1 i</p>
      <p>no
1 i ¬X! ¬Y</p>
      <p>X!Y
i
no
1 s ¬Y! ¬X s
no Supp. X
1 s⇤ s⇤
All 4 MP, AC, DA no Supp.Y Supp.Y</p>
      <p>Supp. X
1 s⇤ s⇤
no Supp. Y Supp. Y MP, AC, MT All 4
MP, AC MP, AC, DA MP, AC, MT All 4
b</p>
      <p>1 c
1 s¬X!no¬Ys
no Supp. X Supp. X</p>
      <p>Reasoning</p>
      <p>no
1 i Y!X</p>
      <p>1 b
i
1 c ¬X! ¬Y c
1 s⇤¬Y! ¬Xs⇤ 1 s¬Y!no¬Xs ¬Y! ¬X
no Supp. Y Supp. Y MP MP, MT no Supp. X Supp. X MP, DA, MT
no X!Y</p>
      <p>None
MP, DA MP, DA, MT
2.4</p>
    </sec>
    <sec id="sec-5">
      <title>Oaksford-Chater Probabilistic Model</title>
      <p>
        Oaksford and Chater [
        <xref ref-type="bibr" rid="ref10 ref11 ref9">11, 9, 10</xref>
        ] propose a probabilistic model for conditional
reasoning. By using a 2 ⇥ 2 contingency table (Table 4), they represent
conditional rules, where a = P(X) and b = P(Y), probabilities of the antecedent and
consequent, respectively and ✏ = P(¬Y|X) is the exception parameter.
      </p>
      <p>This model belongs to the new Bayesian paradigm – it assumes that inference
form endorsement is proportional to the conditional probability of the conclusion
given the minor premise. So, from Table 4, they derived expressions for the
inference form endorsements as follows:</p>
      <p>MP: P(Y|X) = 1
AC: P(X|Y) =
✏
b
a(1
✏)</p>
      <p>
        The ✏-MMT: Mental Models and Probabilities
In previous work [
        <xref ref-type="bibr" rid="ref20 ref21">20, 21</xref>
        ] we proposed a probabilistic cognitive model for
conditional reasoning that is based on a mental model approach and showed that it is
a valuable competitor among Bayesian models. We represent conditionals using
mental models, interpret them as possible worlds, allowing for an application of
a probabilistic assignment as described by ✏-semantics [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ].
      </p>
      <p>
        ✏-semantics is a ‘formal framework for belief revision’, as introduced by Pearl
[
        <xref ref-type="bibr" rid="ref14">14</xref>
        ]. Belief statements are interpreted as high probability statements and newly
available evidence leads to belief revision. The following definition [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ] lays the
basis for the probabilistic aspect of ✏-MMT:
      </p>
      <p>Let L be the language of propositional formulas, and let a truth-valuation
for L be a function t, that maps the sentences in L to the set {1, 0},
(1 for ‘true’, 0 for ‘false’). To define a probability assignment over the
sentences in L, we regard each truth valuation t as a world w and define
P(w) such that Pw P(w) = 1. This assigns a probability measure to
each sentence l of L.
✏-MMT takes the conditional’s mental model representation of all
propositions’ truth state combinations, meaning that the material implication
interpretation is abandoned by allowing the X ¬Y model to exist. From now on, we will
refer to them as possible worlds. Given a conditional premise “If X then Y”, all
possible worlds describing the states of X and Y along with the corresponding
probability values assigned to them are shown in Table 5.</p>
      <p>
        We follow the approach of previous accounts in the Bayesian paradigm [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ],
and interpret inference form endorsements as a conditional probability of the
conclusion given the minor premise.
      </p>
      <p>By applying the definition of conditional probability, as shown in Eq. 1, to
Table 5, we derive the following inference form endorsement expressions:
MP: P(Y|X) =
AC: P(X|Y) =</p>
      <p>p4
p3 + p4</p>
      <p>p4
p2 + p4</p>
      <p>Benchmark and Predictive Modeling Results
We implemented a benchmark within the framework CCOBRA. The main goal
is to examine the cognitive models’ ability to predict a value in the range
0100, by taking into consideration how close the model’s prediction is to the
individual’s true answer. We evaluate a model’s performance by calculating the
mean individual absolute di↵erence between a prediction and the corresponding
true answer. A lower value indicates better performance.</p>
      <p>
        The cognitive models are first exposed to existing data – a training set, from
which it can learn about the individual’s reasoning behavior. Then, the model
is challenged with predicting answers in unseen data – a test set. Here, we use
Singmann et al.’s [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] experimental data for both training and testing. In this
(1)
case, the CCOBRA framework uses a leave-one-out cross-validation method –
models are fit on every participant, except the one whose answers should be
predicted. The same is done for each participant. The models are fit to the
training data by optimizing their parameter values in order to minimize the
absolute di↵erence between the prediction and the true answer. That was done
using Python’s scipy.optimize.minimize3 with the method Sequential Least
Squares Programming (SLSQP), which allows for constrained minimization.
      </p>
      <p>In order to set a performance lower bound, our benchmark has a Random
model, which simply gives a random value between 0-100 as a prediction. Since
the models do not adapt to an individual, the upper bound is set by an empirical
Most Frequent Answer (MFA) model, which gives the median of the responses
as a prediction.</p>
      <p>The results are shown in Figure 4. In the deductive case, the Suppositional
Sequential model has an outstanding performance for both experiments (Exp.
1: 26.72, Exp. 2: 27.98), whereas the other models’ perform similarly, reaching
an average absolute di↵erence of 30.57 (Exp. 1) and 29.70 (Exp. 2). In the
inductive case, however, the Bayesian Oaksford-Chater model takes the lead
with an absolute di↵erence of 16.08 in Exp. 1 and 17.90 in Exp. 2. Once again,
a similar performance among the other models can be seen, having an average
absolute di↵erence of 16.82 (Exp. 1) and 18.57 (Exp. 2).</p>
      <p>
        We have two mental model based approaches, a probabilistic endorsement
adaptation of Oberauer’s [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ] formalization MMT with Directionality, and our
proposed model ✏-MMT that follows the Bayesian paradigm. ✏-MMT
outperforms MMT with Directionality in Exp. 1, but performs slightly worse in Exp.
2. Though, the di↵erence between the two models is no more than 0.55 in any
scenario. It is noteworthy that the total number of free parameters that each
model needs for one task is di↵erent. Here, ✏-MMT takes the lead with only
three parameters, in contrast to five for MMT with Directionality.
      </p>
      <p>We continue our analysis as we look into the models’ parameter values to
learn more about the di↵erence between deductive and inductive instructions.
For that purpose the main focus is on ✏-MMT’s p2 and p3, Oaksford-Chater’s
✏ and MMT with Direcionality’s a and e parameters. Their values for each
instruction and conditional type are shown in Table 6.</p>
      <p>Material implication states that a conditional “If X then Y” is false when X
is true and Y is false. These three models are able to recognize this state through
their parameters for counterlogical conditionals through low values under
deductive instructions. More specifically, ✏-MMT’s p3 parameter describes the belief in
the world ! 3, where X = 1 and Y = 0. Oaksford-Chater’s ✏ parameter describes
the conditional probability P(¬Y|X). MMT with Directionality’s e parameter
describes the probability of the mental model X ¬Y to be added to the mental
representation. In both experiments, these parameters have an increase in value
for individuals that had inductive instructions showing the material implication
interpretation under deductive instructions.
3 https://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.
minimize.html
Exp.1: Deductive
Exp.1: Inductive
Exp.2: Deductive
Exp.2: Inductive</p>
      <p>
        Another point of interest is the influence of alternatives and disablers, under
inductive instructions, when background knowledge is taken into consideration.
In the following, we use X for the antecedent and Y for the consequent (“If X
then Y”). The presence of many alternatives means that Y occurs even if X has
not. ✏-MMT’s p2 parameter describes the belief in that world (! 2) and MMT
with Directionality’s a parameter describes the probability of the corresponding
mental model (¬X Y) to be added to the representation. In both experiments, for
prological conditionals the values of these parameters are higher in comparison
to counterlogical, reflecting the influence of alternatives. On the other hand, the
presence of many disablers means that even if X has happened, Y has not.
✏MMT’s p3 parameter describes the belief in that world (! 3), Oaksford-Chater’s
✏ parameter describes the conditional probability for that scenario, P(¬Y|X)
and MMT with Directionality’s e parameter describes the probability of the
corresponding mental model (X ¬Y) to be added to the representation. Similarly,
in both experiments for counterlogical conditionals, these parameter values are
higher in comparison to prological ones, pointing to the e↵ect of disablers.
Research approaches have been divided between emphasizing logical validity and
focusing on content and background knowledge. Those are di↵erent types of
reasoning that one single mechanism cannot cover, leading to arguments that one
of the two approaches is wrong [
        <xref ref-type="bibr" rid="ref17 ref19 ref9">19, 9, 17</xref>
        ]. Singmann and Klauer [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ] show a
double dissociation of the two types of instructions. To further analyze this, we
adapted MPT formalizations of cognitive theories such that they can now
represent experimental data with probabilistic endorsements. Then, we compared
0.34
0.08
0.24
0.02
0.15
0.37
0.44
0.12
their predictive performance to an established Bayesian model and a newly
proposed probabilistic approach based on mental models. We showed that after
exposing conditional models to a training data set, they are capable of
generating predictions on unseen data in the range 0-100. In previous work [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ] we
considered experiments where participants received inductive instructions and
the models reached a mean deviation of ca. 17, which is what we encounter now
as well. However, we learn that their performance drops to ca. 29 when dealing
with deductive instructions. An important finding is that the Suppositional
Sequential formalization stands out under deductive instructions, while the
performance of the Oaksford-Chater model exceeds that of the others under inductive
instructions. With this we show that only one single theory can not explain all
reasoning process under all circumstances. The di↵erence in performance lays
basis for future research to examine the di↵erence in reasoning processes under
various conditions through cognitive modeling. Additionally, we showed that
✏MMT, Oaksford-Chater and MMT with Directionality are capable to account for
the e↵ect of instruction, by showing the material implication interpretation
under deductive instructions. More detailed research is necessary for Suppositional
Sequential, especially given that it excels for deductive instructions.
Additionally, we confirmed our finding [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ] that ✏-MMT can successfully account for the
influence of disablers and alternatives when background knowledge is taken into
consideration. Both ✏-MMT and MMT with Directionality are based on mental
models, have a similar performance and account for instruction and content
effect in the same way through their parameter values. The advantage of ✏-MMT
is that it needs only three free parameters in contrast to five. That indicates
that the same information can be represented by ✏-MMT in a less complex and
computationally more ecient way, while still preserving the same psychological
interpretation and providing valuable insight. As mentioned before, the MPTs
for MMT and the Suppositional Theory show that certain combinations of
inference forms are lacking from the trees and cannot be accepted according to
the theories. Even though we are not looking into combinations of accepted
inferences, but rather their separate probabilistic endorsements, the parameter
values still depend on the combinations. In future work we would look into how
influential this is on the model’s predictive performance. Namely, is the lack of
combinations hurting the model, or is it accurately describing human reasoning?
Furthermore, an even more exciting next step would be to challenge the
models to adapt to individuals as well. With this we continue the thrilling path of
challenging the predictive capabilities of models and gaining insight about the
individual reasoning processes under various e↵ects.
      </p>
    </sec>
  </body>
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