Methods

Participants

Sixty-four adult participants (26 males, 38 females, age M±sd: 25±6.9) were tested in this experiment, equally divided between four conditions. They were all native Dutch speakers and had no dyslexia or hearing problems. Recruit- ment was conducted via the Leiden University participant recruitment site and the experimenters’ personal networks. Participants received either monetary compensation or course credits for participation.

Procedure

The experiment consisted of a familiarization phase followed by a test phase. Participants sat behind a computer screen and wore the provided headphones (Sennheiser HD 201). They were assigned to one of two instruction conditions: Language or Group. In the case of the Language condition, participants received

the following instructions: You will now hear fragments of a non-existing lan-

guage. Listen carefully. In the test phase you will have to indicate whether the fragment you hear is part of this language.In the Group condition, participants

heard no information about what to listen to before the familiarization: You

miliarization phase, participants heard syllable triads separated by short pauses (1 sec). The familiarization triads followed either an XYX grammar or an XXY grammar. One group of participants was exposed to 15 different triads all re- peated three times, another group to three different triads, all repeated 15 times. The familiarization phase lasted approximately two minutes in both ex- posure conditions.

During the test phase, participants were instructed to score several triads on whether or not they belonged to the same language or group as the triads they were familiarized with. In the Language condition, the instructions were as

follows: Indicate whether the following fragments belong to the same language

as in the listening phase. For yes press ’z’. For no press ’/’. Respond as quickly and accurately as possible.Participants in the Group condition were instructed

as follows: Indicate whether the following fragments belong to the same group

as in the listening phase. For yes press ’z’. For no press ’/’. Respond as quickly and accurately as possible.During the test, 18 test triads were presented twice, separated into two test blocks, such that in total 36 test trials were heard. Within the two blocks, the test triads were presented in random order. There was no break between blocks. The experiment lasted approximately 10 minutes. Upon completing the experiment, participants were requested to fill out a questionnaire asking what strategy they used for solving the task (what they paid attention to), as well as their age, sex, languages spoken and whether and to what degree they had been diagnosed with dyslexia or hearing problems. Stimuli

Familiarization. The stimuli were identical to those used in chapter 2, Ex-

periment 1. They consisted of eight consonant-vowel syllables (mo, do, ka, sa,

pu, nu, le, fi) produced by a phonologically-trained female native speaker of standard Dutch (C.C.L.). All syllables were equalized in length, average pitch, and amplitude using Praat (Boersma & Weenink, 2014). They were concate- nated into triads following two grammars, XYX and XXY, with 100 ms pauses between each syllable (Figure 5.1). Each syllable was assigned to a different letter (A through H) for each participant, to avoid pseudo replication (e.g.,

syllable A could be ba for one participant, but fi for another, see chapter 2,

Appendix A). Triads formed by syllables A through F were then randomized and concatenated into a continuous stream with 1 sec pauses between each triad. Depending on the experimental condition, either 3 different triads were repeated 15 times or 15 different triads were repeated 3 times in the stream (from now on referred to as 3 triads or 15 triads conditions).

Test

The test stimuli consisted of both triads with an XYX pattern and triads with an XXY pattern. These triads either consisted of new combinations of the syllables used for familiarization (combination triads), or of new syllables (novel

triads; Table 5.2). The two syllables that were not used during familiarization (G and H) were used to create the novel triads and were therefore different for each participant. Test triads were concatenated in the same fashion as the familiarization triads, with 100ms pauses between the syllables.

See Figure 5.2 for a list of all triads used in familiarization and test, and see chapter 2, Appendices A and B for a full list of letter-to-syllable correspon- dences.

mo mo fi ka ka do le le nu

0 7000 ms

1000 ms 370 ms 100 ms

Figure 5.1:Example of three triads of the familiarization stream. Length of pauses between syllables (100 ms), pauses between triads (1000 ms) and syllables (370 ms) are indicated.

Analysis

A percentage correct (%C) score was calculated per participant for their indi- vidual responses to the test triads, by adding the correct yes responses to the correct no rejections, and dividing their sum by the total number of trials. This resulted in a score between 0 and 1, with 1 indicating perfect discrimination (all triads were correctly marked as either belonging to the same language/group or not) and 0.5 indicating performance at chance level.

The two types of instructions (Language vs. Group) and the two types of familiarization (3 triads vs. 15 triads) created four experimental conditions. We analyzed the effect of these variables with an LMM. The dependent variables were the %C of the novel triads and the combination triads. The covariates were the type of familiarization grammar (XYX or XXY) and the sex of par- ticipants, with subject nested in experiment as random factor. Interactions between the independent variables were measured with a linear regression af- terwards. Furthermore, per experimental condition, we tested whether the %C scores deviated from random (0.5) with a one-sided t-test.

The reported strategies of the participants were divided into three cate- gories: pattern, sounds, or other. This division was based on the usage of these

Table 5.2:Triads used for familiarization and the Combination and Generalization test con- ditions. Letters represent a consonant-vowel syllable, which was different for each participant. Bold familiarization triads were used in the 3 triads familiarization condition. Combination triads were not used in Experiment 3. See chapter 2, Appendices A and B for letter-to-syllable correspondences and full strings.

Familiarization triplets Combination triplets Generalization triplets

XYX XXY XYX XXY XYX XXY

ADA AAD ACA AAC GHG GGH

AEA AAE BDB BBD HGH HHG

AFA AAF CEC CCE

BAB BBA DCD DDC

BCB BBC EAE EEA

BFB BBF FAF FFA

CAC CCA FEF FFE

CDC CCD CFC CCF DBD DDB DED DDE DFD DDF EBE EEB ECE EEC EFE EEF

particular words or words with similar meaning by the participants. Reported strategies categorized as ’pattern’ included reports with any of the follow- ing words: pattern, rhythm, order, and combination. The strategies grouped into the category ’sounds’ involved self-reported listening for any of the fol- lowing: sounds, words, vowels, and consonants. The category ’other’ included self-reported strategies such as: feeling and intuition. These reported strategies were tested in an ANOVA for an effect on the %C score for the novel triads. Post-hoc t-tests were used to test which strategies were related to differences in %C scores. The same types of analyses were conducted for all four experi- ments presented in this paper. The variables used in the LMM are explained separately for each experiment.

5.3.2

Results

The model showed no effect of instruction (Group: M = .66, Language: M = .71, F = 1.39, p = 0.24) or the number of familiarization items on the %C score for the combination triads (3 triads: M = .64, 15 triads: M = .73, F = 2.61, p = .12), nor an interaction effect of these two factors (F = .12, p = .73, Figure 5.2a). Participants’ sex or the familiarization grammar (XXY or XYX) also did not explain the output variance (Sex: F = 0.05, p = .82; Fam. grammar: F = 2.68, p = .11). Variable reduced models increased the statistical power but did not alter the results of this analysis.

In all four experimental conditions, subjects correctly discriminated the grammars consisting of combination triads with known syllables (Language 3 triads: M±sd = .68±.2, p = .002; Language 15 triads: M±sd = .74±.2, p < .001; Group 3 triads: M±sd = .59±.17, p = .004; Group 15 triads: M±sd = .72±.2, p = .001; Figure 5.2a).

Novel triads

Also for the novel triads, there was no effect of instructions or number of famil- iarization items on the discrimination performance (Instructions: F = 0.313, p = .58; No. of triads: F = 0.08, p = .78).

One-sided t-tests showed that in each experimental condition subjects were, on average, unable to discriminate correctly between the grammars, as the results did not differ from performance at random (Language 3 triads: M±sd = .62±.2, p = .2; Language 15 triads: M±sd = .55±.3, p = .48 Group 3 triads: M±sd = .59±.2, p = .07; Group 15 triads: M±sd = .6±.2, p = .11; Figure 5.2b).