Visual Working Memory is More Tolerant Than Visual Long-Term Memory

Human visual memory is tolerant, meaning that it supports object recognition despite variability across encounters at the image level. Tolerant object recognition remains one capacity in which artificial intelligence trails humans. Typically, tolerance is described as a property of human visual long-term memory (VLTM). In contrast, visual working memory (VWM) is not usually ascribed a role in tolerant recognition, with tests of that system usually demanding discriminatory power-identifying changes, not sameness. There are good reasons to expect that VLTM is more tolerant; functionally, recognition over the long-term must accommodate the fact that objects will not be viewed under identical conditions; and practically, the passive and massive nature of VLTM may impose relatively permissive criteria for thinking that two inputs are the same. But empirically, tolerance has never been compared across working and long-term visual memory. We therefore developed a novel paradigm for equating encoding and test across different memory types. In each experiment trial, participants saw two objects, memory for one tested immediately (VWM) and later for the other (VLTM). VWM performance was better than VLTM and remained robust despite the introduction of image and object variability. In contrast, VLTM performance suffered linearly as more variability was introduced into test stimuli. Additional experiments excluded interference effects as causes for the observed differences. These results suggest the possibility of a previously unidentified role for VWM in the acquisition of tolerant representations for object recognition. Public Significance Statement Human visual memory is tolerant, meaning that it supports object recognition despite variability across encounters at the image level. Tolerance is not yet fully understood in neural or computational terms. Typically, tolerance is ascribed to visual long-term memory (VLTM)-recognition taking place over longer durations and relying on passive storage mechanisms. Visual working memory (VWM), in contrast, requires active maintenance, operates only on the order of seconds (perhaps minutes), and is typically thought of as discriminating, noticing differences not tolerating them. But here, comparing VWM and VLTM tolerance directly and for the first time revealed that VWM is more tolerant. These results suggest a previously unidentified role for VWM in the acquisition of tolerant representations for object recognition.