Introduction: Memory deficits play a core role in many neurodegenerative, psychiatric and traumatic disorders. Repeated training enables motor skills and associations to be maintained in memory long after learning. Here, in contrast, we demonstrate a distinct form of long-term memory that enables visual patterns to persist in memory over prolonged durations but which also functions to prevent false-positive detection by proactively inhibiting ongoing learning.
Methods: We devised a visual search paradigm that required participants to search for particular items from other similar items presented on a screen. Two orthogonal categories of items were presented: (i) summer vs. winter clothing and (ii) upper vs. lower body clothing. The subjects were always asked to identify the summer clothing item. For the first experiment subjects searched for both upper- and lower-body items on the same day. In the second experiment, subjects searched for an upper-body clothing item on the first day of testing, and on the second day searched for both upper- and lower-body items. The third experiment was identical to the second except that subjects were given an interference search task immediately following training on the first day.
Results: We found that searching for items of a particular category can improve performance in the long term. We also found that prior learning led to suppression of performance when searching for novel subordinate-level items within the same category. Introduction of an interference task following training did not lead to reduced performance for the initially trained item but rather prevented the suppression of performance improvement for the new items.
Conclusions: These findings suggest a neural mechanism that may allow attended visual patterns to persist in memory over prolonged durations. From this perspective, visual search training appears to produce a similar effect to that observed in other memory phenomena such as item recognition and associative memory. However, it appears that this initial learning suppresses the ability to learn similar visual patterns once consolidation occurs. The prospective benefit of such a system could be to enhance specificity to trained visual features within the environment by suppressing the ability to learn similar but distinct visual features.
Patient Care: This research provides evidence of long-term visual learning, suggesting a possible neural basis for visual memory that is often impaired following damage to the brain. Understanding the origin of this form of learning, will allow for the development of appropriate treatments in the future.
Learning Objectives: 1) Visual search is influenced by both short- and long-term memory processes.
2) Initial learning with one visual category leads to suppression of learning of another visual category.
3) Interference of initial learning prevents suppression of learning another visual category.