Verbal working memory encodes phonological and semantic information differently

Examining the semantic relatedness effect on working memory with ad hoc categories

The semantic relatedness effect, a memory advantage of semantically related items (e.g., "penguin, giraffe, goat"), is well established in the literature on working memory (WM). Nevertheless, it remains unclear what mechanisms are responsible for this effect. Although an influential account ascribes it to the cue-dependent retrieval process (e.g., "animal" works as a cue for "penguin, giraffe, goat"), this account has not yet been fully investigated. This is partly because the influence of cues cannot be directly tested in typical studies using common categories (e.g., "animal" is likely to be generated and used by participants, but the generation and use of cues are uncontrollable for the experimenter). The present study, by introducing ad hoc categories and cueing ad hoc category labels, directly tested the influence of cues. Specifically, seemingly unrelated items (e.g., "bone, fly, car") were presented with or without the corresponding ad hoc category label (e.g., "things that dogs chase"). Four experiments demonstrated that providing ad hoc category labels affected WM performance. Importantly, providing the labels improved item memory in WM (Experiments 2 and 3). This supported the retrieval-cue account. Nevertheless, the effect was small (Experiments 2 and 3) and was not found in an experiment (Experiment 1). In contrast, providing the labels had a substantial and systematic effect on long-term memory, suggesting that the manipulation of providing the labels, per se, was successful. The current study's implications for research on WM and ad hoc categories were also discussed.

Low-frequency neural activity tracks syntactic information through semantic mediation

How our brain integrates single words into larger linguistic units is a central focus in neurolinguistic studies. Previous studies mainly explored this topic at the semantic or syntactic level, with few looking at how cortical activities track word sequences with different levels of semantic correlations. In addition, prior research did not tease apart the semantic factors from the syntactic ones in the word sequences. The current study addressed these issues by conducting a speech perception EEG experiment using the frequency-tagging paradigm. Participants (N = 25, Meanage = 23;4, 16 girls) were asked to listen to different types of sequences and their neural activity was recorded by EEG. We also constructed a model simulation based on surprisal values of GPT-2. Both the EEG results and the model prediction show that low-frequency neural activity tracks syntactic information through semantic mediation. Implications of the findings were discussed in relation to the language processing mechanism.

Semantic similarity is not emotional: No effect of similarity defined by valence, arousal, and dominance on short-term ordered recall

In short-term ordered recall tasks, phonological similarity impedes item and order recall, while semantic similarity benefits item recall with a weak or null effect on order recall. Ishiguro and Saito recently suggested that these contradictory findings were due to an inadequate assessment of semantic similarity. They proposed a novel measure of semantic similarity based on the distance between items in a three-dimensional space composed of the semantic dimensions of valence, arousal, and dominance. We conducted an experimental examination of their proposal. In four experiments, participants performed an immediate serial recall or an immediate order reconstruction task. Performance of dissimilar lists was contrasted with performance for semantically similar lists defined by valence, arousal, and dominance or by the typical latent semantic analysis. Two sets of words were used to assess the reproducibility of the findings and similar results were observed with both sets. As expected, when similarity was defined with latent semantic analysis, items were better recalled without noticeable impact on their order. However, contrary to Ishiguro and Saito's predictions, when similarity was defined with valence, arousal and dominance, no effect emerged.

Mismatch Negativity Unveils Tone Perception Strategies and Degrees of Tone Merging: The Case of Macau Cantonese

BACKGROUND/OBJECTIVES

Previous studies have examined the role of working memory in cognitive tasks such as syntactic, semantic, and phonological processing, thereby contributing to our understanding of linguistic information management and retrieval. However, the real-time processing of phonological information-particularly in relation to suprasegmental features like tone, where its contour represents a time-varying signal-remains a relatively underexplored area within the framework of Information Processing Theory (IPT). This study aimed to address this gap by investigating the real-time processing of similar tonal information by native Cantonese speakers, thereby providing a deeper understanding of how IPT applies to auditory processing.

METHODS

Specifically, this study combined assessments of cognitive functions, an AX discrimination task, and electroencephalography (EEG) to investigate the discrimination results and real-time processing characteristics of native Macau Cantonese speakers perceiving three pairs of similar tones.

RESULTS

The behavioral results confirmed the completed merging of T2-T5 in Macau Cantonese, and the ongoing merging of T3-T6 and T4-T6, with perceptual merging rates of 45.46% and 27.28%, respectively. Mismatch negativity (MMN) results from the passive oddball experiment revealed distinct temporal processing patterns for the three tone pairs. Cognitive functions, particularly attention and working memory, significantly influenced tone discrimination, with more pronounced effects observed in the mean amplitude of MMN during T4-T6 discrimination. Differences in MMN peak latency between T3-T6 and T4-T6 further suggested the use of different perceptual strategies for these contour-related tones. Specifically, the T3-T6 pair can be perceived through early signal input, whereas the perception of T4-T6 relies on constant signal input.

CONCLUSIONS

This distinction in cognitive resource allocation may explain the different merging rates of the two tone pairs. This study, by focusing on the perceptual difficulty of tone pairs and employing EEG techniques, revealed the temporal processing of similar tones by native speakers, providing new insights into tone phoneme processing and speech variation.

I remember it now, so I'll remember it later: Working memory strength guides predictions for long-term memory performance

Judgments of learning (JOLs) are assumed to be made inferentially, based on cues. This cue-utilization approach substituted the theory that memory strength guides JOLs. The rejection of this theory ignores the existence of two memory systems: working memory (WM), which holds representations immediately accessible, and long-term memory (LTM), which is a permanent store. By manipulating and measuring WM strength, we tested a revised version of the memory-strength theory in which JOLs are guided by WM representations. In Experiment 1, participants memorized sequences of two or four colored objects, then they provided JOLs for an LTM test of these objects, and performed a WM test on the objects' colors. After learning 200 objects, the LTM test followed. Sequence-length affected WM, but not LTM performance. JOLs, however, were higher for sequences of two than for four objects and correlated higher with WM than LTM performance. We replicated these results with a simultaneous presentation of the objects (Experiment 2), in the absence of a WM test (Experiment 3), and in a word-pair task (Experiment 4). Overall, our findings are consistent with the revised memory-strength theory. WM strength should therefore be considered when examining the factors guiding JOLs.

Semantic relatedness can impair memory for item locations

While memory for semantically related items is improved over unrelated items in many cases, relatedness can also lead to memory costs. Here we examined how the semantic relatedness of words within a display influenced memory for their locations. Participants learned the locations of words inside grid displays; the words in a given display were either from a single category or were from different assorted categories. When a display containing words from a single category was compared to a scrambled display containing words from multiple categories, location memory performance was rendered worse, while word recall performance was significantly improved. Our results suggest that semantically structured spaces can both help and harm memory within the context of a location memory task. We hypothesize that relatedness can improve memory performance by increasing the likelihood that matching candidates will be retrieved, yet might worsen performance that requires distinguishing between similar target representations.

The Semantic Similarity Effect on Short-Term Memory: Null Effects of Affectively Defined Semantic Similarity

Studies on short-term memory have repeatedly demonstrated the beneficial effect of semantic similarity. Although the effect seems robust, the aspects of semantics targeted by these studies (e.g., categorical structure, associative relationship, or dimension of meaning) should be clarified. A recent meta-regression study inspired by Osgood's view, which highlights affective dimensions in semantics, introduced a novel index for quantifying semantic similarity using affective values. Building on the results of the meta-regression of past studies' data with that index, this study predicts that semantic similarity is deleterious to short-term memory if it is manipulated by affective dimensions, after controlling for other confounding factors. This prediction was directly tested. The experimental results of the immediate serial recall task (Study 1) and immediate serial reconstruction of order task (Study 2) indicated null effects of semantic similarity by affective dimensions and thus falsified the prediction. These results suggest that semantic similarity based on affective dimensions is negligible.

Working Memory Maintenance of Visual and Auditory Spatial Information Relies on Supramodal Neural Codes in the Dorsal Frontoparietal Cortex

The frontoparietal attention network plays a pivotal role during working memory (WM) maintenance, especially under high-load conditions. Nevertheless, there is ongoing debate regarding whether this network relies on supramodal or modality-specific neural signatures. In this study, we used multi-voxel pattern analysis (MVPA) to evaluate the neural representation of visual versus auditory information during WM maintenance. During fMRI scanning, participants maintained small or large spatial configurations (low- or high-load trials) of either colour shades or sound pitches in WM for later retrieval. Participants were less accurate in retrieving high- vs. low-load trials, demonstrating an effective manipulation of WM load, irrespective of the sensory modality. The frontoparietal regions involved in maintaining high- vs. low-load spatial maps in either sensory modality were highlighted using a conjunction analysis. Widespread activity was found across the dorsal frontoparietal network, peaking on the frontal eye fields and the superior parietal lobule, bilaterally. Within these regions, MVPAs were performed to quantify the pattern of distinctness of visual vs. auditory neural codes during WM maintenance. These analyses failed to reveal distinguishable patterns in the dorsal frontoparietal regions, thus providing support for a common, supramodal neural code associated with the retention of either visual or auditory spatial configurations.