Symbolic Integration, Not Symbolic Estrangement, For Double-Digit Numbers

Symbolic and non-symbolic number representations are thought to share common neural substrates. However, recent studies have shown that the two numerical systems are more distinct than previously thought. These disparate findings may be explained by the use of sequential presentations of symbolic and non-symbolic quantities, the use of magnitude-reliant tasks, or the use of limited number ranges. We investigated whether adults integrate symbolic and non-symbolic numerical information during a non-magnitude-based task in which symbolic and non-symbolic double-digit numerical information is shown simultaneously. Participants viewed images in which symbolic numerals or letter pairs were superimposed on non-symbolic numerical stimuli and were asked to determine whether the text was a numeral or letter, ignoring the dots. After perceptual biases were taken into account, participants were more accurate and faster in their judgments when symbolic and non-symbolic information matched than when information mismatched, suggesting that adults can integrate symbolic and non-symbolic numerical information.