Looks like SNARC spirit: coexistence of short- and long-term associations between letters and space

Many studies have demonstrated spatial-numerical associations, but the debate about their origin is still ongoing. Some approaches consider cardinality representations in long-term memory, such as a Mental Number Line, while others suggest ordinality representations, for both numerical and non-numerical stimuli, originating in working or long-term memory. To investigate how long-term memory and working memory influence spatial associations and to disentangle the role of cardinality and ordinality, we ran three preregistered online experiments (N = 515). We assessed spatial response preferences for letters (which only convey ordinal but no cardinal information, in contrast to numbers) in a bimanual go/no-go consonant-vowel classification task. Experiment 1 (‘no-go’ trials: non-letter symbols) validated our setup. In Experiments 2 and 3, participants learned an ordinal letter sequence prior to the task, which they recalled afterwards. In Experiment 2, this sequence was merely to be maintained (‘no-go’ trials: non-letter symbols), whereas in Experiment 3, it needed to be retrieved during the task (‘no-go’ trials: letters outside the sequence). We replicated letter-space associations based on the alphabet stored in long-term memory (i.e., letters earlier/later in the alphabet associated with left/right, respectively) in all experiments. However, letter-space associations based on the working memory sequence (i.e., letters earlier/later in the sequence associated with left/right, respectively) were only detected in Experiment 3, where retrieval occurred during the task. Spatial short- and long-term associations of letters therefore seem to coexist. These findings support a hybrid model that incorporates both short- and long-term representations, which applies similarly to letters as to numbers.