Figure 1.
Stimuli and experimental paradigm. A, Spoken stimuli matrix and articulatory properties. The 18 syllables were selected according to the place of articulation (i.e., bilabial/labiodental and alveolar) and manner of articulation (i.e., stop, fricative, and nasal). B, Experimental procedure and task description. Example of a typical match-to-sample trial during attend to vowels task. Subjects received instructions per block, in which they attended to consonants or vowels, respectively, and conducted a match-to-sample decision within slow-event related trials. Each block started with the visual presentation of a task cue (i.e., attention target vowel or consonant), indicating which task to perform in the next 27 trials. Each trial started with a fixation period in which a fixation cross was presented at the center of screen, together with a syllable sound (340 ms). After a jittered ISI (jitter: 6–8 s) a visual cue (i.e., a written letter, vowel, or consonant) was presented for 2 s, followed by the immediate subject’s response by pressing a button either with the right index finger (for match trials) or middle index finger (for mismatch trials). The response was followed by a jittered ISI (4–10 s) to complete the jittered ITI period (12–16 s) before the next trial started. C, Schematic representation of the fMRI acquisition sequence and its relationship to the syllable sounds presented to the participants. Vow, attentd to vowels task; Con, attend to consonants task; Syll, syllable; TA, time of acquisition; TR, time for repetition; Phase, opposite phase encoding volumes acquired for distortion correction.