Temporal Sentence Grounding (TSG) aims to identify relevant moments in an untrimmed video that semantically correspond to a given textual query. Despite existing studies having made substantial progress, they often overlook the issue of spurious correlations between video and textual queries. These spurious correlations arise from two primary factors: (1) inherent biases in the textual data, such as frequent co-occurrences of specific verbs or phrases, and (2) the model's tendency to overfit to salient or repetitive patterns in video content. Such biases mislead the model into associating textual cues with incorrect visual moments, resulting in unreliable predictions and poor generalization to out-of-distribution examples. To overcome these limitations, we propose a novel TSG framework, causal intervention and counterfactual reasoning that utilizes causal inference to eliminate spurious correlations and enhance the model's robustness. Specifically, we first formulate the TSG task from a causal perspective with a structural causal model. Then, to address unobserved confounders reflecting textual biases toward specific verbs or phrases, a textual causal intervention is proposed, utilizing do-calculus to estimate the causal effects. Furthermore, visual counterfactual reasoning is performed by constructing a counterfactual scenario that focuses solely on video features, excluding the query and fused multi-modal features. This allows us to debias the model by isolating and removing the influence of the video from the overall effect. Experiments on public datasets demonstrate the superiority of the proposed method. The code is available at https://github.com/Tangkfan/CICR.

Weakly supervised temporal sentence grounding aims to identify semantically relevant video moments in an untrimmed video corresponding to a given sentence query without exact timestamps. Neuropsychology research indicates that the way the human brain handles information varies based on the grammatical categories of words, highlighting the importance of separately considering nouns and verbs. However, current methodologies primarily utilize pre-extracted video features to reconstruct randomly masked queries, neglecting the distinction between grammatical classes. This oversight could hinder forming meaningful connections between linguistic elements and the corresponding components in the video. To address this limitation, this paper introduces the dual semantic reconstruction network (DSRN) model. DSRN processes video features by distinctly correlating object features with nouns and motion features with verbs, thereby mimicking the human brain's parsing mechanism. It begins with a feature disentanglement module that separately extracts object-aware and motion-aware features from video content. Then, in a dual-branch structure, these disentangled features are used to generate separate proposals for objects and motions through two dedicated proposal generation modules. A consistency constraint is proposed to ensure a high level of agreement between the boundaries of object-related and motion-related proposals. Subsequently, the DSRN independently reconstructs masked nouns and verbs from the sentence queries using the generated proposals. Finally, an integration block is applied to synthesize the two types of proposals, distinguishing between positive and negative instances through contrastive learning. Experiments on the Charades-STA and ActivityNet Captions datasets demonstrate that the proposed method achieves state-of-the-art performance.