Error rates ANOVA.

Perception can be shaped by our expectations, which can lead to perceptual illusions. Similarly, long-term memories can be shaped to fit our expectations, which can generate false memories. However, it is generally assumed that short-term memory for percepts formed just 1 or 2 seconds ago accurately represents the percepts as they were at the time of perception. Here 4 experiments consistently show that within this timeframe, participants go from reliably reporting what was there (perceptual inference accurately reflecting the bottom-up input), to erroneously but with high confidence reporting what they expected to be there (memory report strongly influenced by top-down expectations). Together, these experiments show that expectations can reshape perceptual representations over short time scales, leading to what we refer to as short-term memory (STM) illusions. These illusions appeared when participants saw a memory display which contained real and pseudo-letters (i.e. mirrored letters). Within seconds after the memory display disappeared, high confidence memory errors increased substantially. This increase in errors over time indicates that the high confidence errors do not (purely) result from incorrect perceptual encoding of the memory display. Moreover, high confidence errors occurred mainly for pseudo-to-real letter memories, and much less often for real-to-pseudo-letter memories, indicating that visual similarity is not the primary cause of this memory-bias. Instead ‘world knowledge’ (e.g., which orientation letters usually have) appear to drive these STM illusions. Our findings support a predictive processing view of the formation and maintenance of memory in which all memory stages, including STM, involve integration of bottom-up memory input with top-down predictions, such that prior expectations can shape memory traces.

感知可受预期塑造，进而引发知觉错觉（perceptual illusion）。与之类似，长期记忆也可被调整以契合自身预期，从而催生错误记忆。然而，学界普遍认为，仅在1至2秒前形成的知觉相关短时记忆，能够精准还原感知瞬间的知觉原貌。本研究借助4项一致性实验证实：在此时间窗口内，参与者的报告从可靠呈现当时实际呈现的刺激（即知觉推断精准反映自下而上输入（bottom-up input）），转变为虽存在错误但置信度极高地报告预期会出现的内容（即记忆报告受自上而下预期（top-down expectations）的强烈调控）。综上，这些实验表明，预期能够在短时尺度下重塑知觉表征，进而产生我们所称的短时记忆（STM）错觉。这类错觉出现于参与者观看包含真字母与伪字母（pseudo-letters，即镜像字母）的记忆呈现刺激时。在记忆呈现刺激消失后的数秒内，高置信度记忆错误率显著攀升。这类随时间推移而增长的错误率表明，高置信度记忆错误并非（完全）源于对记忆呈现刺激的错误知觉编码。此外，高置信度错误主要出现在伪字母转真字母的记忆任务中，而真字母转伪字母的情况则极为少见，这表明视觉相似性并非该记忆偏差的主要诱因。取而代之的是，‘世界知识’（world knowledge，例如字母通常的朝向）似乎是这类STM错觉的驱动因素。本研究结果支持记忆形成与维持的预测加工观：包括短时记忆在内的所有记忆阶段，均涉及自下而上的记忆输入与自上而下的预测的整合，即先前预期能够塑造记忆痕迹。