(~20 minutes)

Phoneme Discrimination

This test assesses the phoneme perception system using an AB (same-different) discrimination task with minimal-pair phoneme contrasts (Binder et al., 2017). Phonetic features such as place of articulation, voicing, manner of articulation, and vowel color are known to differ in discriminability, and discriminability also depends, to a lesser degree, on position of a phoneme within a syllable. Phonetic contrast type and syllable structure are thus the main factors assessed.

To minimize the possibility of discrimination based on pre-phonemic acoustic differences, all trials – including “same” trials containing the same phonemes – consist of non-identical recordings.

Materials:

• digitally recorded natural utterances of short non-word phoneme strings (e.g., /ta/) by a single talker
• equal numbers of CV (consonant-vowel), CCV, VC, and VCC strings
• same pairs = item paired with a different recording of the same item
• different pairs = item paired with a similar item differing in a single phonetic feature (e.g., /ta, ka/)
• equal numbers of pairs differing in place (/ta, ka/), voicing (/ta, da/), manner (/ta, na/) and vowel (/ta, tæ/)

Procedure (see figure):

• same-different touch response following each pair, using screen icons: √√ = same, XX = different
• 80 “same” trials, 80 “different” trials
• 20 “different” trials for each minimal contrast type (place, voicing, manner, vowel)
• The 160 trials are divided into two balanced 80-trial blocks to avoid fatigue.

Trials per condition:

	Syllable Structure
Contrast	CV	VC	CCV	VCC	Total
None	20	20	20	20	80
Manner	5	5	5	5	20
Place	5	5	5	5	20
Voicing	5	5	5	5	20
Vowel	5	5	5	5	20

Data analysis:

• d' scores computed for overall performance, each contrast type, and each syllable type

A second matched set of 160 trials is available for optimizing reliability or repeat assessment.