Extended Data Fig. 2: Additional analyses of neural similarity across trials and in relation to recall behavior.

(a) A standardization procedure was used to obtain a proper effect size estimate for the correlation strength between stimulus-predicted item similarity pattern and the observed neural similarity pattern across trials at each time window of the task. At each time point of the task within each subject, the observed Spearman rank-order correlation values of these two variables are contrasted against a null distribution created by shuffling the trial labels of the cued item across 5,000 iterations. The standardized correlation strength is then calculated based on the mean and standard deviation of this shuffled distribution. This approach normalized the intrinsic noise in the data at each time window of the task, facilitating group-level comparison. (b) Item-specific information during STM retention in the MTL can be primarily attributed to high-frequency activity at 70–150 Hz based on the stimulus–neural association analysis outlined in Fig. 2. Based on the power values at different canonical frequency bands, we calculated the standardized correlation between the trial-by-trial stimulus similarity pattern and the trial-by-trial neural similarity pattern to capture information about the cued item in the multivariate neural data. Across participants, we find that MTL signals are significantly associated with the cued item during the STM delay period primarily in the 70–150 Hz high-frequency band (cluster-based correction, p_corrected < 0.05, outlined in an orange rectangle), with little evidence showing item-specific information in other lower frequency bands. (c) Time-varying analysis of the neural separation score and participants’ absolute recall errors suggests that the neural separation score during the STM delay period, especially during the first 500-ms following stimulus offset, can well predict later recall precision. This suggests that our findings in Fig. 2e can be generalized across adjacent timepoints during the STM retention interval. Error bars represent the s.e.m. across participants. Significant timepoints after cluster-based correction for multiple comparisons at the 0.05 level are marked in yellow.