Annual Meeting of the Belgian Association for Psychological Sciences pages:52-52
Annual Meeting of the Belgian Association for Psychological Sciences location:Leuven, Belgium date:26 May 2008
This study investigated young adults' performance and strategy use when estimating different numerosities of coloured cells in a 20 x 20 grid. Participants were assigned to either a strategic condition in which they had 20 seconds to make their estimates or a perceptual condition in which stimuli were presented for only 1 second. Both groups were informed that each grid contained 400 cells in total. We expected that participants in the strategic condition would use a variety of counting-based strategies, whereas participants in the perceptual condition would solely rely on perceptual-based strategies. We collected accuracy and reaction-time data and verbal reports of strategy use. Results showed that participants in the strategic condition used between 3-8 different estimation strategies. For example, they relied on the ration between the green and empty cells or counted a group of cells and then multiplied it with the number of groups with an estimated equal numerosity as the first group. However, participants in the strategic condition also used perceptual, non-counting based strategies. As expected, participants in the perceptual condition did not report any counting-based strategies. Despite these differences in strategy use between conditions, we only found significant differences in accuracy within the middle numerosity range (numerosities: 80-320). Moreover, in both conditions, estimation errors became larger to approximately halfway the numerosity range and then decreased again towards 400. This indicates that participants were able to minimize their estimation errors by using their knowledge of the total grid size, even under very limited time conditions.