Contextual Cueing of Tactile Search Is Coded in an Anatomical Reference Frame

This work investigates the reference frame(s) underlying tactile context memory, a form of statistical learning in a tactile (finger) search task. In this task, if a searched-for target object is repeatedly encountered within a stable spatial arrangement of task-irrelevant distractors, detecting the target becomes more efficient over time (relative to nonrepeated arrangements), as learned target-distractor spatial associations come to guide tactile search, thus cueing attention to the target location. Since tactile search displays can be represented in several reference frames, including multiple external and an anatomical frame, in Experiment 1 we asked whether repeated search displays are represented in tactile memory with reference to an environment-centered or anatomical reference frame. In Experiment 2, we went on examining a hand-centered versus anatomical reference frame of tactile context memory. Observers performed a tactile search task, divided into a learning and test session. At the transition between the two sessions, we introduced postural manipulations of the hands (crossed <-> uncrossed in Expt. 1; palm-up <-> palm-down in Expt. 2) to determine the reference frame of tactile contextual cueing. In both experiments, target-distractor associations acquired during learning transferred to the test session when the placement of the target and distractors was held constant in anatomical, but not external, coordinates. In the latter, RTs were even slower for repeated displays. We conclude that tactile contextual learning is coded in an anatomical reference frame. Public Significance Statement Tactile search with the fingers improves over time when observer encounter repeated arrangements ("contexts") of tactile search stimuli, a form of statistical learning referred to as tactile contextual cueing. This memory-based guidance of tactile search requires a process by which the current display input is matched against representations stored in tactile memory. Because our hands move in peripersonal space, tactile (finger) memory can be formed with regard to certain coordinate systems. The present study addresses the reference frame(s) of tactile memory. We distinguish between 2 external (environment-centered, hand-centered) and an anatomical reference frame. Manipulations of reference frames were achieved by limb posture changes across a learning and test session (intended for the acquisition and retrieval of tactile context cues, respectively). We show that learned tactile context cues are retrieved only when the anatomical (but not external) coordinates are held constant across limb posture changes. This suggests that tactile context cueing is coded in anatomical coordinates.