OBJETIVOS DE LA PROPUESTA DE INTERVENCIÓN

Twenty-eight seven-month-old infants (mean age = 212 days; age range= 198-228 days; 12 female) from Dutch monolingual families participated. The infants had normal development and hearing, and no major problems during pregnancy or birth. One infant was born 15 days premature; the others were full term. One infant had a dyslexic father, and one a father and brother who were dyslexic; the others had no language problems in the immediate family. The parents received five euro or a present of a toy for their participation.

Stimuli and design

Ten pairs of bisyllabic nouns and the corresponding sentences were selected from the EEG stimuli. We used a slightly adapted version of the HPP study of Jusczyk and Aslin (1995), with ten consecutive blocks (instead of one block as is normally the case in HPP studies). Each block consisted of ten tokens of the same word (Familiarization), followed by four trials of four sentences each (Test): two trials with the familiarized word in each of the four sentences, and two trials with its unfamiliar pair (see Table 2).

The increased number of Familiarization and Test blocks, as well as the design of Familiarization, closely resembled the ERP study which required a high number of experimental trials to reach an adequate signal-to-noise ratio. The Test blocks were closer to the original HPP study, in that there were four consecutive trials in different conditions instead of randomized sentences. Four versions of the experiment were created as in the ERP study. Each version was presented to seven infants.

Table 2: Example of an experimental trial in the adjusted HPP study.

Familiarization Ten tokens of zwaluw or viking

Test Een viking gaat op reis naar verre landen. Die kleine viking is niet sterk maar slim. Dat is die andere viking met veel vijanden. Pieter zag die viking uit het noorden.

Een zwaluw vliegt vaak laag over het landschap. De kleine zwaluw kan heel goed vliegjes vangen. Ik zie een andere zwaluw in de wei.

's Ochtends is die zwaluw altijd erg actief. Een viking gaat op reis naar verre landen. Die kleine viking is niet sterk maar slim. Dat is die andere viking met veel vijanden. Pieter zag die viking uit het noorden.

Een zwaluw vliegt vaak laag over het landschap. De kleine zwaluw kan heel goed vliegjes vangen. Ik zie een andere zwaluw in de wei.

's Ochtends is die zwaluw altijd erg actief.

Procedure

The experiment took place in a three-sided booth. Infants sat on a caregiver's lap facing the center panel of the booth. The test booth had a red light attached at eye level to the center panel and a blue light attached to each side panel. A camera was mounted behind the center panel under the red light, with its lens through a hole in the panel. The experimenter observed the infant on a monitor connected to the camera. A computer and a response box were situated behind the center panel for stimulus presentation. The experimenter used the response box to start and stop the stimuli, and relay information on the direction and duration of the head turns to the computer. The infant could not see the experimenter behind the center panel. During the experiment, the experimenter and the caregiver listened to masking music over closed-ear headphones.

The stimuli were presented from loudspeakers mounted behind the light on each side panel. During Familiarization, the sidelights flashed contingent upon the infants’ looking behavior. The lights were not linked to the presentation of the Familiarization stimuli. Following each Familiarization, the corresponding Test trials were presented. The trials were alternated, and played equally often from the two speakers while the light on the respective side was flashing. Looking time of the infant in the direction of the stimulus was measured. If the infant looked away for more then two consecutive seconds, the trial was ended, and the next trial or block started. If the infant continued to look in the direction of the stimulus, the trial was played to the end. The experiment was continued for as long as the infant was interested. Each infant heard at least three blocks. However, the results showed considerably reduced looking times after the first block. Therefore, we report the results of the first block here; this is directly analogous to a standard HPP design.

There were four versions of this first block. Half of the infants were familiarized with the Dutch word zwaluw ([zwa·lyw]; ‘swallow’; n=7) or viking ([ví·kΙŋ]; ‘viking’; n=7), and tested on sentences containing these words (n=14). The other half were familiarized with the Dutch word pudding ([pΨdΙŋ]; ‘pudding’; n=7) or sauna ([sΑu·na]; ‘sauna’; n=7), and tested on sentences containing these words (n=14). For each group, the trials with sentences containing the familiarized words were then compared with trials with sentences containing the other word. The looking times to each trial were summed and inspected. Looking times below 2020 ms (i.e., mean onset + mean length of the target words) were excluded from analysis. The average looking times (looking times to blocks in each condition, familiarized versus unfamiliar, summed and divided by two in each case) were subjected to repeated measures analysis of variance.