Abstract:

Audiovisual integration is the integration of visual and auditory information into a unified, coherent and stable perceptual process. Although endogenous spatial attention can promote audiovisual integration in youth, studies have found differences in endogenous spatial attention between older adults and youth. It is unclear how endogenous spatial attention affects audiovisual integration in older adults and how audiovisual integration differs between older adults and young adults under endogenous spatial attention conditions. In this study, using the endogenous cue-target paradigm, three experiments investigated how endogenous spatial attention affects the audiovisual integration of elderly individuals under 50% (Experiment 1), 70% (Experiment 2), and 90% (Experiment 3) conditions.

A mixed 2 (participant type: elderly vs. young) × 2 (cue type: valid cue vs. invalid cue) × 3 (target stimulus type: A vs. V vs. AV) experimental design was used. The visual stimulus was a 2° × 2° red (RGB: 234, 86, 97) and yellow (RGB: 247, 200, 125) intersecting meta−pattern, the auditory stimulus was a 1600 Hz, 60 dB sinusoidal tone presented by ear headphones, and the audiovisual stimulus was visual and auditory stimuli presented simultaneously on the same side. The gaze screen was presented for 500 ms, followed by a cue screen for 200 ms. The cue was an arrow pointing left or right. After a time interval of 600 ms, the target stimulus (A vs. V vs. AV) was presented in a box on the left or right side for 100 ms. Before the experiment, participants were informed that the cue validity was 50% for Experiment 1, 70% for Experiment 2, and 90% for Experiment 3 and were asked to judge the orientation of the target stimulus and to press the (N/M) key quickly and accurately.

From the reaction time and accuracy results in all experiments (Table 1/2/3), it is clear that the reaction time of elderly people is significantly slower than that of younger people. From the relative amount of multisensory response enhancement (rMRE), we can see that (1) audiovisual integration was weaker in older adults than in younger adults regardless of cue validity (Figure 1); (2) at 50% cue validity (Experiment 1), audiovisual integration in the valid cue condition was not significantly different from that in the invalid cue condition for both older and younger adults (Fig. 1a); (3) at 70% cue validity (Experiment 2), audiovisual integration in the valid cue condition was not significantly different from that in the invalid cue condition for older adults, and audiovisual integration in the valid cue condition was significantly higher than that in the invalid cue condition for younger adults (Figure 1b); and (4) at 90% cue validity (Experiment 3), audiovisual integration in the valid cue condition was significantly higher than that in the invalid cue condition for both older and younger adults (Figure 1c).

Endogenous spatial attention had different moderating effects on audiovisual integration in older adults under different cue validity conditions and could promote audiovisual integration in older adults under high cue validity conditions. The findings further support the spatial uncertainty hypothesis and deepen the understanding of the interaction between endogenous attention and audiovisual integration.

Key words: endogenous spatial attention, audiovisual integration, older adult, cue validity