Long-Term Memory for Haptically Explored Objects: Fidelity, Durability, Incidental Encoding, and Cross-Modal Transfer

The question of how many of our perceptual experiences are stored in long-term memory has received considerable attention. The present study examined long-term memory for haptic experiences. Blindfolded participants haptically explored 168 everyday objects (e.g., a pen) for 10 s each. In a blindfolded memory test, they indicated which of two objects from the same basic-level category (e.g., two different pens) had been touched before. As shown in Experiment 1 (N = 26), memory was nearly perfect when tested immediately after exploration (94%) and still high when tested after 1 week (85%). As shown in Experiment 2 (N = 43), when participants explored the objects without the intention to memorize them, memory in a 1-week delayed surprise test was still high (79%), even when assessed with a cross-modal visual memory test (73%). These results indicate that detailed, durable, long-term memory representations are stored as a natural product of haptic perception.