Table 2.

Summary table of results

ConditionIndependent variablesDependent variablesTestResults
Maturation: cross-sectional300 ms ISI tone pair4- and 7-month-old cross-sectional age groups4 months: P1, N1, P2, N2
7 months: P1, N1, P2, N2 (to tone 1); P1T2, N1T2, P2T2, N2T2, (to tone 2)
Independent t testSignificantly faster and larger P1 to tone 1 response for 7-month-old group compared with younger group
70 ms ISI tone pair4- and 7-month-old cross-sectional age groups4 and 7 months: P1, N1, P2Independent t testSignificantly faster and smaller P1 and P2 responses for 7-month-old group compared with younger group
Significantly bigger negative peaks for 7-month-old children
Group differences
    Amplitude and latency differences300 ms ISI tone pair7-month-old AEx, PEx, and NC groupsFour P2 peaks (2 from the standard pair, 1 from the pre-deviant standard and 1 from the deviant tone of the target pair)3 × 4 factorial ANOVASignificantly larger P2 response for the deviant tone (1200 Hz) for all 3 groups
The AEX group had significantly bigger P2 responses for the oft-repeated 800 Hz tone
70 ms ISI tone pair7-month-old AEx, PEx, and NC groupsTwo P2 peaks (1 from standard and 1 from deviant tone)3 × 2 factorial ANOVASignificantly smaller P2 responses for the NC group compared with the AEx and PEx groups
70 ms ISI tone pair7-month-old AEx, PEx, and NC groupsN2* and P2 peaks of deviant waveOne-way ANOVAThe AEx and PEx groups have significantly faster N2* and P2 responses
The AEx group had significantly larger N2* peak responses
    Morphological differences70 ms ISI tone pair7-month-old AEx, PEx, and NC groupsPresence vs absence of new emerging peaksχ2A majority of infants in the AEx group showed the presence of emerging peaks
Generalization
    Multideviant paradigmMultideviant paradigm7-month-old AEx, PEx, and NC groupsP1 and N1 peaks of the standard waveOne-way ANOVAThe AEx group had significantly faster P1 peak responses and more mature P1 and N1 responses
Multideviant paradigm7-month-old AEx, PEx, and NC groupsP1 and N1 peaks for the 3 deviants3 × 3 factorial ANOVAThe AEx group had significantly faster P1 peak responses
Significant interactions for N1 peak responses where the NC group was notably slower compared to the other two groups
    Gap deviantGap deviant of multideviant paradigmAEx group vs NC groupPresence vs Absence of P2–N2 complexχ2The AEx group significantly differed from the NC group while there was no significant difference between PEx and NC groups
PEx group vs NC group
Gap deviant of multideviant paradigmGroup (AEx vs NC) vs subgroup (presence of P2–N2 complex vs absence of P2–N2 complex)N2 peak response2 × 2 ANOVASignificant interactions found where the AEx group that showed the P2–N2 complex had faster latencies as compared to their naive peers
Gap deviant of multi-deviant paradigmGroup (AEx vs NC) vs subgroup (presence of P2–N2 complex vs absence of P2–N2 complex)MMR (mismatch response)2 × 2 ANOVAInfants that showed the P2–N2 complex had significantly larger MMR responses compared with those infants who did not show the P2–N2 complex