Mem-Gallery: Benchmarking Multimodal Long-Term Conversational Memory for MLLM Agents

AuthorsYuanchen Bei, Tianxin Wei, Xuying Ning et al.

2026

TL;DR

Mem-Gallery uses a three-dimensional evaluation framework over 1,711 QA pairs to show that explicit multimodal memory like MuRAG boosts overall F1 to 0.6966 on long-term conversations.

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THE PROBLEM

Multimodal agents lack long-term conversational memory across sessions and modalities

Existing benchmarks either drop visual modality or restrict to single-session context, so they cannot test evolving multimodal memory over long conversations.

This breaks evaluation of MLLM agents in realistic multi-session settings, where missing multimodal memory leads to poor reasoning, weak knowledge management, and unsafe behavior.

HOW IT WORKS

Mem-Gallery — Benchmark Construction, Conversational Environment, Evaluation Framework

Mem-Gallery combines Benchmark Construction, a unified Conversational Environment for Memory, and an Evaluation Framework with Memory Extraction and Adaptation, Memory Reasoning, and Memory Knowledge Management.

You can think of Mem-Gallery like a long-term lab notebook for agents, where every multimodal session is logged, indexed, and then probed with targeted tests.

This design lets Mem-Gallery stress-test capabilities such as conflict-aware knowledge resolution and multimodal visual-centric reasoning that a plain context window cannot reliably expose.

DIAGRAM

Mem-Gallery Conversational Memory Evaluation Flow

This diagram shows how Mem-Gallery feeds multi-session multimodal conversations into memory agents and evaluates their responses across the three task families.

DIAGRAM

Mem-Gallery Data and Task Pipeline

This diagram shows how Mem-Gallery constructs conversations and QA tasks, then runs benchmarking and analysis.

PROCESS

How Mem-Gallery Handles a Multi-Session Conversation

  1. 01

    Data Sourcing

    Mem-Gallery performs Data Sourcing by curating images and text, then generating structured backgrounds like role profiles and topics for Benchmark Construction.

  2. 02

    Conversation Generation

    Mem-Gallery runs Conversation Generation with newly created stories and topic-based clustering, producing coherent multi-session multimodal dialogues for the Conversational Environment for Memory.

  3. 03

    Evaluation Data Generation

    Mem-Gallery executes Evaluation Data Generation by prompting LLMs and humans to create QA pairs aligned with the Evaluation Framework and annotated evidence clues.

  4. 04

    Benchmark Evaluation

    Mem-Gallery conducts Benchmark Evaluation where memory agents store conversations, retrieve with unified protocols, and are scored on F1, BLEU-1, EM, and LLM-Judge.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    New Scenario and Dataset

    Mem-Gallery formulates multimodal long-term conversational memory as an evolving system and builds multi-session conversations with 240 sessions, 3,962 rounds, and 1,003 images.

  • 02

    Evaluation Framework

    Mem-Gallery introduces an Evaluation Framework that structures 1,711 QA pairs into Memory Extraction and Adaptation, Memory Reasoning, and Memory Knowledge Management with explicit evidence clues.

  • 03

    Benchmark Takeaways

    Mem-Gallery benchmarks thirteen memory systems and reveals that MuRAG reaches 0.6966 overall F1 while naive Full Memory multimodal storage performs 8.08 percent worse F1.

RESULTS

By the Numbers

Overall F1

0.6966

+0.0992 over NaiveRAG

VS LLM-Judge

0.8856

vs NaiveRAG 0.7402

FR F1

0.6724

FR F1 +0.0852 over NaiveRAG 0.5852

TTL F1

0.8177

TTL F1 +0.1651 over NaiveRAG 0.6526

Mem-Gallery evaluates memory systems on its own multimodal long-term conversational benchmark, testing extraction, reasoning, and knowledge management. The 0.6966 overall F1 and 0.8856 LLM-Judge on visual-centric search show that explicit multimodal memory in MuRAG is crucial for Mem-Gallery tasks.

BENCHMARK

By the Numbers

Mem-Gallery evaluates memory systems on its own multimodal long-term conversational benchmark, testing extraction, reasoning, and knowledge management. The 0.6966 overall F1 and 0.8856 LLM-Judge on visual-centric search show that explicit multimodal memory in MuRAG is crucial for Mem-Gallery tasks.

BENCHMARK

Main evaluation results on Mem-Gallery based on Qwen-2.5-VL-7B

Overall F1 on Mem-Gallery across representative memory systems.

KEY INSIGHT

The Counterintuitive Finding

Mem-Gallery shows that Full Memory multimodal storage achieves only 0.3354 overall F1, which is 8.08 percent worse than Full Memory text at 0.3625.

This is surprising because adding images should help, but Mem-Gallery reveals that naive multimodal accumulation can crowd out useful text and inject irrelevant visual noise.

WHY IT MATTERS

What this unlocks for the field

Mem-Gallery unlocks a controlled way to stress-test multimodal long-term memory, including conflict detection, knowledge resolution, and answer refusal across 1,711 QA pairs.

Builders can now compare memory systems like MuRAG, A-Mem, and MemoryOS under identical multimodal conditions, making it practical to design agents with robust, efficient long-horizon memory.

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