Grapheme–color synesthesia can enhance immediate memory without disrupting the encoding of relational cues

Abstract

Previous evidence has suggested that graphemecolor synesthesia can enhance memory for words, but little is known about how these photisms cue retrieval. Often, the encoding of specific features of individual words can disrupt the encoding of ordered relations between words, resulting in an overall decrease in recall accuracy. Here we show that the photisms arising from grapheme-color synesthesia do not function like these item-specific cues. The influences of high and low word frequency on the encoding of ordered relations and the accuracy of immediate free recall were compared across a group of 10 synesthetes and 48 nonsynesthetes. The main findings of Experiment 1 showed that the experience of synesthesia had no adverse effect on the encoding of ordered relations (as measured by input-output correspondence); furthermore, it enhanced recall accuracy in a strictly additive fashion across the two word frequency conditions. Experiment 2 corroborated these findings by showing that the synesthetes only outperformed the nonsynesthetes when the materials involved words and letters, not when they involved digits and spatial locations. Altogether, the present findings suggest that synesthesia can boost immediate memory performance without disrupting the encoding of ordered relations.

Do children with grapheme‐colour synaesthesia show cognitive benefits?

“…Our results can be compared to an adult study conducted by Gibson et al . () who found significantly longer letter spans in adult letter‐colour synaesthetes. Our own study suggests that this capacity may be emerging even in children as young as 10–11 years.…”

“…We point out that our non‐significant finding in Matrix recall contrasts with our near‐significant finding in letter span . This pattern also perfectly mirrors findings in the adult literature: no superiority in matrix recall (Rothen & Meier, ; Rothen & Meier, ; Yaro & Ward, ) but superior performance in span tasks (Gibson et al ., ). This difference across tasks may stem from the fact that matrices typically contain many more graphemes than span sets and so may exceed any enhanced memory span capacity of synaesthetes.…”

“…To summarize our findings, our data support previous studies showing cognitive advantages for synaesthetes over non‐synaesthetes (e.g., Rothen & Meier, ; Radvansky et al ., ; Yaro & Ward, ) and we found no disadvantages. We found a near‐significant advantage in a letter‐span task which would be compatible with either a dual‐coding account (in which synaesthetes perform better because their memory traces for graphemes are more richly encoded, e.g., Gibson et al ., ) or a theory of improved perceptual organization (in which synaesthetes perform better because this organization makes performance more efficient; Ramachandran & Azoulai, ). Importantly, however, we also found superior performance in an assessment of processing speed for stimuli unrelated to synaesthesia, which cannot accounted for within a dual‐coding theory.…”

Two plus blue equals green: Grapheme-color synesthesia allows cognitive access to numerical information via color

“…In a common form of synesthesia, grapheme-color synesthesia, graphemes (i.e., letters, punctuation marks or numbers) evoke percepts of color (Cohen Kadosh et al, 2005; Day, 2005; Simner et al, 2006). The percepts can be quite vivid and are cognitively accessible in the sense that they are verbally reportable and can be used by the synesthete to perform certain perceptual and cognitive tasks ranging from color matching (Arnold, Wegener, Brown, & Mattingley, 2012; Blake, Palmeri, Marois, & Kim, 2005) to visual search (Palmeri, Blake, Marois, Flanery, & Whetsell, 2002; Ramachandran & Hubbard, 2001; Ramachandran & Hubbard, 2001) and facilitate learning and memory (Gibson, Radvansky, Johnson, & McNerney, 2012; Gross, Neargarder, Caldwell-Harris, & Cronin-Golomb, 2011; Rothen, Meier, & Ward, 2012; Watson, Blair, Kozik, Akins, & Enns, 2012). However, past accounts of grapheme-color synesthetes generally suggest that the inverse is not the case.…”

Impaired acquisition of novel grapheme-color correspondences in synesthesia

“…Grapheme-color synesthetes demonstrate enhanced memory recall for word lists that evoke synesthetic colors, line drawings that do not evoke synesthetic colors, and for memory of colors themselves (Yaro and Ward, 2007; Rothen and Meier, 2010; Gibson et al, 2012). However, memory enhancements in synesthesia are generally restricted to colors and visual stimuli and are not a generalized trait (for a review see Rothen et al, 2012).…”