Developmental trends in the facilitation of multisensory objects with distractors

Abstract

Sensory integration and the ability to discriminate target objects from distractors are critical to survival, yet the developmental trajectories of these abilities are unknown. This study investigated developmental changes in 9- (n = 18) and 11-year-old (n = 20) children, adolescents (n = 19) and adults (n = 22) using an audiovisual object discrimination task with uni- and multisensory distractors. Reaction times (RTs) were slower with visual/audiovisual distractors, and although all groups demonstrated facilitation of multisensory RTs in these conditions, children's and adolescents' responses corresponded to fewer race model violations than adults', suggesting protracted maturation of multisensory processes. Multisensory facilitation could not be explained by changes in RT variability, suggesting that tests of race model violations may still have theoretical value at least for familiar multisensory stimuli.

Keywords: audiovisual; development; distractors; facilitation; multisensory; race model; variance.

Figure 1

(A) A selection of possible trials for blocks in which the bird was the target and the cat and dog were distractors. Empty dashed boxes indicate possible locations of visual stimuli. Auditory targets and distractors could occur with visual targets, visual distractors or in isolation. Visual stimuli are presented in (B) and auditory stimuli sound waveforms, which had a duration of 433 ms, are shown in (C), top to bottom: bird, cat, dog. Note: illustrations are not to scale.

Figure 2

(A) Mean and median percentage (±interquartile range) errors rate (false alarms) to auditory, visual and audiovisual distractor-alone trials with stimuli from one (auditory, ad1, visual, vd1, audiovisual advd1) or both (auditory, ad2, visual, vd2, audiovisual advd2) non-target animals, for the groups, 9-year-olds, 11-year-olds, adolescents, and adults. (B) Mean and median percentage (±interquartile range) error rate (misses) for auditory (AT), visual (VT) and audiovisual targets (ATVT) in the no distractor (nd), and auditory (ad), visual (vd), and audiovisual distractor (advd) conditions for the groups, 9-year-olds, 11-year-olds, adolescents, and adults.

Figure 3

Mean reaction times (RTs; ±95%CI) for auditory (AT), visual (VT) and audiovisual (ATVT) targets in the no distractor (nd), auditory distractor (ad), visual distractor (vd) and audiovisual distractor (advd) conditions for the groups, 9-year-olds, 11-year-olds, adolescents and adults.

Figure 4

The percentage of participants in each group showing visual and auditory dominance (i.e., faster mean RTs to visual or auditory targets) for the four distractor conditions: no distractor (nd), auditory distractor (ad), visual distractor (vd) and audiovisual distractor (advd) conditions. Gray portion represents visual dominance. White portion represents auditory dominance.

Figure 5

Mean cumulative density functions (CDFs) of reaction times (RTs) to auditory (AT, green line), visual (VT, blue line), and audiovisual (ATVT, black line) targets in the no distractor (nd), and auditory (ad), visual (vd) and audiovisual (advd) distractor conditions, for the groups 9-year-olds, 11-year-olds, adolescents, and adults. Red line represents the CDF of the bound (AT+VT). Asterix (^*) indicates a significant violation of the race model predicted inequality (Miller, 1982).

Figure 6

Coefficient of variation (Cv, ± 95% CI) for auditory (AT), visual (VT) and audiovisual (ATVT) targets in the no distractor (nd), auditory distractor (ad), visual distractor (vd) and audiovisual distractor (advd) conditions for the groups, 9-year-olds, 11-year-olds, adolescents, and adults.