Poster #104 - Threshold and Emergent Process of Visual Consciousness of Shape in Young Children

• In Event: Poster Session 01

Abstract

We perceive things consciously when they are presented for a sufficient length of time (threshold) to be processed. Pre-threshold things do not emerge in consciousness, but post-threshold things do (all-or-none emergent process) (Dehaene & Changeux, 2011). Studies using a backward masking task have shown that the threshold for objective discrimination performance and subjective visibility in visual consciousness in adults is 50 ms (Del Cul et al., 2006). Moreover, infant studies have shown that the threshold for 5- and 10-month-olds is 150 ms, and for 15-month-olds it is 100 ms (Gelscov & Kouider, 2010). However, studies are yet to determine whether and how the visual consciousness threshold and emergent process develop. The current study examined the thresholds and emergent processes of visual consciousness of the most basic shape stimuli in young children and adults.

In this study, young children (N=16, range=[62–75 months]) and adults (N=16, range=[20–31 years]) performed a visual figure identification task (Figure 1). The fixation mark was followed by one of two geometrical shapes (square and diamond), and shown for one of four durations (40, 80, 120, and 160 ms) for adults and six durations (50, 150, 250, 350, 450, and 550 ms) for children. The participants identified the presented shape (objective discrimination), and indicated their awareness of the stimulus on a 4-point Perceptual Awareness Scale (PAS, not visible, slightly visible, almost visible, and clearly visible) based on subjective visibility. To examine the thresholds and emergent processes for objective discrimination and subjective visibility between children and adults, we conducted a two-way ANOVA on the thresholds and the sharpness of the slopes of the fitted models as the emergent process trend. The independent variables were measurement (subjective vs. objective) and age group (young children vs. adults). The dependent variables were the parameters inferring the threshold and the sharpness.

There was a main effect on the age group on the thresholds: F(1,30)=64.6, p<0.001, partial η2=0.683 (Figure 2a). There was no main effect on the measurement and no interaction effect: F(1,30)=0.744, p=0.395, partial η2=0.024 and F(1,30)=0.707, p=0.407, partial η2=0.023. Moreover, there was no main effect on the age group and measurement and interaction effect on the sharpness, F(1,30)=1.73, p=0.199, partial η2=0.054, F(1,30)=0.857, p=0.362, partial η2=0.028, and F(1,30)=0.00256, p=0.987, partial η2=0.000 (Figure 2b).

The results show children's thresholds for objective discrimination and subjective visibility are larger than adults. There is no difference between the threshold of objective discrimination and subjective visibility in both children and adults. The sharpness of objective discrimination and subjective visibility was similar in children and adults. These findings suggest that the emergent process of visual consciousness tends to be similar in adults and young children, but the threshold in young children is larger than in adults.

Authors

• Ryoichi Watanabe, Kyoto University
  Presenting Author

• Yusuke Moriguchi, Kyoto University