Magnitude estimation of visual displays: area, numerosity, and mean size

다국어 초록 (Multilingual Abstract)

Our visual system can compute various magnitudes of a visual scene such as numerosity and mean size. Previous studies have shown that both number and mean size were estimated efficiently and accurately. However, the inter-relationship among them and the ability to judge area have not been investigated. In the current study, we asked participants to estimate the three different magnitudes on the same stimuli. In Experiment 1, we found all three perceived magnitudes were positively correlated to each other. Experiment 2 showed that the performance of estimating three magnitudes deteriorated when the tasks were randomly presented. These results suggest that there might be a common magnitude estimation system to process those magnitudes. In Experiment 1, we also found that number and mean size of a display influenced three magnitudes, whereas density had no effects on them. Participants underestimated mean size when they overestimated numerosity, and vice versa. This opposite trend was found again when the size of test display changed in Experiment 3. In addition, we were able to show very high correlation between perceived mean size and predicted mean size using the ratio between perceived area and numerosity. These results suggest that area and numerosity might be used when we estimate mean size. In conclusion, visual system seems to use common resources to judge various magnitudes of visual displays.