Processing of time reference in agrammatic speakers of Akan: a language with grammatical tone

Figures & data

Figure 1. Example of the Akan TART-comprehension, with the target sentence “the man ate the orange”, as in (3)

Figure 2. Example of the Akan TART-production pictures depicting present habitual aspect in Akan. The Akan verbs twerɛ: to write and kan: to read, as in (4) are written above the respective pictures

Figure 3. Percent mean accuracy scores per condition per group of participants in comprehension-TART, including error bars

Figure 4. Percent mean accuracy scores per condition per group of participants in comprehension-TART, including error bars

Table 1. Percentage of accuracy scores on non-/linguistic tone discrimination task

Patients	Non-linguistic tone Discrimination (%)	Linguistic (lexical) tone discrimination (%)
P1	98	93
P2	90	97
P3	92	87
P4	72	87
P10	90	93
Mean	88.4	91.4

Table 2. Generalized linear mixed model output on the Akan agrammatic speakers’ accuracy

GLMER output
Term	β	Standard error	z-Value	p-Value
(Intercept: Condition = Fut, Task = Comp)	0.6292	0.2852	2.206	p = 0.0274*
Condition = PresHab	1.9766	0.4336	4.559	p < 0.001***
Condition = Past	−1.5779	0.3594	−4.391	p < 0.001***
Task = Prod	1.5942	0.3700	4.309	p < 0.001***
ConditionPresHab:TaskProd	−2.6619	0.5376	−4.951	p < 0.001***
ConditionPast:TaskProd	−0.4461	0.4570	−0.976	p = 0.3290
Post-Hoc Analysis: Multiple Comparisons of Means (Tukey Contrasts)
PresHab.Comp – Fut.Comp	1.9766	0.4336	4.559	p < 0.001***
Past.Comp – Fut.Comp	−1.5779	0.3594	−4.391	p < 0.001***
Past.Comp – PresHab.Comp	−3.5545	0.4412	−8.056	p < 0.001***
PresHab.Prod – Fut.Prod	−0.6853	0.4884	−1.403	p = 0.7115
Past.Prod – Fut.Prod	−2.0240	0.4661	−4.343	p < 0.001***
Past.Prod – PresHab.Prod	−1.3387	0.4315	−3.102	p = 0.0223

Note: Fut = Future; Comp = Comprehension; PresHab = Present Habitual; Prod = Production.

The glmer output was from the model that included an interaction between Task and Condition as well as random slopes for Condition per Participant and random effect for Items: Mod<-glmer(Correct~Condition*Task +(1+ Condition|Participant) + (1|Item), data)

Table 3. Distribution of error types

	Substitution
Patient	Ps-Hab	Ps-PP	FU-Hab	Hab-PP	Hab-Ps	Ps-FU	Short tone duration	Omission	Others
P1	5	1		2	1				1
P2	2		4	2			5	2	7
P4	2			2		4	1		1
P6	0	0		2			8		0
P7	1	4		1			3		1
P8	2	1		6			1		3
P9	0	4		1			1		1
Total	12	10	4	16	1	4	19	2	14
	Direction of time reference substitution errors (%)
		Present	Past	Future
		89%	2%	9%

Note: Ps-Hab = Past to Habitual substitution; Ps-PP = Past to Present Progressive substitution; FU-Hab = Future to Habitual substitution; Hab-PP = Habitual to Present Progressive substitution; Hab-Ps = Habitual to Past substitution; Ps-FU = Past to Future substitution.

Appendix A1. Demographic data of the agrammatic speakers and the none-brain-damaged speakers

Participants	Age	Gender	Handed-ness	Education (years)	Months PO	Etiology/Lesion site	Hemi- plegia	BDAE Scores (%)
Agrammatic speakers
P1	69	M	Right	13	24	CVA Left temporo-parietal	none	91
P2	37	M	Right	16	7	Left fronto-parietal infarct	right	96
P3	19	F	Right	12	7	iCVA Acute left-fronto-parietal-occipital infarct	Right	100
P4	49	M	Right	10	25	CVA Left middle cerebral artery	none	100
P5	76	F	Right	16	12	hCVA left	Right	98
P6	56	M	Right	12	24	CVA left	Right	100
P7	61	M	Right	16	36	hCVA left	Right	94
P8	55	M	Right	12	15	hCVA left	Right	100
P9	50	M	Right	16	28	iCVA left	Right	-
P10	67	F	Right	10	7	hCVA left	Right	96
Non-brain-damaged participants
NBD1	45	F	Right	9
NBD2	35	F	Right	9
NBD3	52	F	Right	16
NBD4	44	M	Right	16
NBD5	71	F	Right	16
NBD6	37	M	Right	12
NBD7	63	M	Right	16
NBD8	48	M	Right	16
NBD9	58	M	Right	12
NBD10	58	F	Right	9

Table

Patients	Speech rate(wpm)	MLU	Ungrammatical sentences	BDAE Scores (_/46)
P1	95	4.8	14 (19.5%)	42
P2	34	2.5	16 (23.5%)	44
P3^a	-	-	-	-
P4	86	3.8	25 (38.4%)	46
P5	63	3.77	11 (17%)	45
P6	66	4.2	14 (23%)	46
P7	48	3.79	14 (24%)	44
P8	79	4.35	13 (20%)	46
P9	58	3.96	16 (25%)	44
P10	66	3.55	12 (18.6%)	42
NBDs’ mean	136	10.5	1.35 (3.2%)	46
NBDs’ range	101 – 156	8.45–12.8	0 – 8%

Note: MLU = Mean Length of Utterance; wpm = word per minute; BDAE = Boston Diagnostic Aphasia Examination. BDAE: subtest of auditory comprehension of nouns, verbs, letters and numbers (both colours and forms were untranslatable to single words in Akan)

P3 did not produce the required speech sample size for a reliable analysis. However, there was a consensus between the Speech and Language Therapist and the neurolinguist that P3 was agrammatic aphasic patient.

Table

Verbs in Akan	Translation	Verbs in Akan	Translation
Examples
susu	to measure	twitwa	to cut
Test items
kan	to read	twerɛ	to write
di	to eat	hwane	to peel
pia	to push	twe	to pull
pepa	to mop	pra	to sweep
pam	to sew	wene	to knit
sensen	to sharpen	bu	to break
nom	to drink	hwie	to pour
to	to iron	bobɔ	to fold

Table

Participants	Past (%)	Habitual (%)	Future (%)
Comprehension-TART
P1	19	94	38
P2	56	88	56
P3	19	100	63
P4	13	94	50
P5	25	94	75
P6	44	88	88
P7	62	94	69
P8	6	88	81
P9	19	94	63
P10	25	94	56
Mean	29	92	64
Production-TART
P1	56	81	94
P2	38	81	38
P3	-	-	-
P4	56	81	100
P5	-	-	-
P6	50	88	100
P7	50	88	100
P8	75	50	94
P9	69	94	94
P10	-	-	-
Mean	56	80	88