Laterality across languages: Results from a global dichotic listening study using a smartphone application

Figures & data

Figure 1. Flow-chart depicting sample selection process and characteristics of sub-samples. *See separate section under Methods. RH = Right-handed. y = years. N = number of subjects. EN = English; NO = Norwegian; EE = Estonian; DE = German.

Figure 2. Three charts depicting the mean correct reports from the right and the left ear comparing (a) the native-stimulus vs. non-native stimulus sample, (b) native-stimulus sub-samples and (c) the non-native languages grouped by phonetic overlap. y-axis = 30 max. Error bars = standard error (SE). *Significant (p < .05) post-hoc pairwise comparisons.

Figure 3. Charts depicting the mean correct reports from the right and the left ear comparing (a) the largest (n > 100) language groups of the main sample, and (b) the three largest (n > 30) English-dialect groups. y-axis = 30 max. Error bars = standard error (SE). *Significant (p < .05) post-hoc pairwise comparisons.

TABLE A1 Analyses overview

	Research question	Sample	N	Exclusion criteria	ANOVA-statistics
Analysis 1	Is the REA universal?	Main sample	4408	General^a	Dependent variable: right ear/left ear scoresFactors: sex, handedness, stimulus languagecovariate: age
Analysis 2a	Is the size of the REA driven by the “nativeness” of the stimulus language?	Native-stimulus sample (100% phonetic overlap)	2348	General^aNon-right-handers	Dependent variable: right ear/left ear scoresFactors: sex, native language Covariate: age
Analysis 2b		Non-native stimulus sample (50%-100% phonetic overlap)	942	General^aNative languages with N < 30Non-English stimuliNon-right-handers	Dependent variable: right ear/left ear scoresFactors: sex, phonetic overlap Covariate: age
Analysis 3a	Does the REA vary across languages/dialects?	Main sample	3028	General^aNative languages with N < 100Non-right-handers	Dependent variable: right ear/left ear scoresFactors: sex, native language Covariate: age
Analysis 3b		Native-English sample	2022	General^aNative languages with N < 30Non-right handers	Dependent variable: right ear/left ear scoresFactors: sex, dialect Covariate: age

^aSee Database and samples section for list of general exclusion criteria.

N = number of subjects, REA = Right-ear advantage.

TABLE A2 Phonetic overlap between native language and stimulus language (English)

Language	Bilabial		Alveolar		Velar		Phonetic overlap
English (stimulus)	p	b	t	d	k	g	−
Afrikaans	p	b	t	d	k	g	6
Chinese	p	−	t	−	k	−	3
Danish	p	−	t	−	k	−	3
Dutch	p	b	t	d	k	−	5
French	p	b	t	d	k	g	6
Hindi	p	b	t	d	k	g	6
Italian	p	b	t	d	k	g	6
Russian	p	b	t	d	k	g	6
Spanish	p	−	t	−	k	g	4
Swedish	p	b	t	d	k	g	6

Mixed sample (N > 30).

TABLE A3 Laterality indices by native language

Native language		N	LI (mean ± SE)	Errors (mean ± SE)	Composition (sex, mean age)
ENGLISH	North American British Australian ALL	1526 419 77 2049	15.8 (± 0.7) 12.5 (±1.3) 17.1 (± 3.3) 15.2 (± 0.6)	7.5 (± 0.1) 8.5 (± 0.2) 7.3 (± 0.5) 7.7 (± 0.1)	65% M, 36 y 70% M, 32 y 75% M, 35 y 66% M, 35 y
Danish		333	11.6 (± 1.5)	8.0 (± 0.2)	68% M, 29 y
Norwegian		252	18.3 (± 1.7)	4.9 (± 0.2)	55% M, 34 y
Hindi		141	5.9 (± 2.4)	11.4 (± 0.3)	84% M, 30 y
Spanish		127	10.3 (± 2.0)	11.9 (± 0.4)	74% M, 34 y
Chinese		145	6.4 (± 2.4)	8.8 (± 0.4)	37% M, 26 y
Estonian		76	6.1 (± 2.0)	8.0 (± 0.5)	50% M, 28 y
Swedish		69	12.9 (± 2.9)	7.7 (± 0.5)	61% M, 35 y
Afrikaans		58	17.8 (± 3.3)	8.2 (± 0.5)	72% M, 34 y
German		44	15.5 (± 3.5)	7.6 (± 0.4)	80% M, 37 y
Russian		42	11.1 (± 3.4)	10.7 (± 0.7)	64% M, 27 y
French		35	9.7 (± 4.4)	10.2 (± 0.8)	71% M, 38 y
Dutch		35	13.5 (± 3.7)	7.2 (± 0.5)	77% M, 37 y
Italian		31	4.5 (± 5.4)	11.1 (± 0.9)	77% M, 40 y

Main sample (N > 30; only right-handers). N = number of subjects, SE = standard error, M = males, y = years, LI = laterality index.