Locomo-Plus: Beyond-Factual Cognitive Memory Evaluation Framework for LLM Agents

AuthorsYifei Li, Weidong Guo, Lingling Zhang et al.

2026

TL;DR

LoCoMo-Plus reframes long-term memory as constraint-consistency under cue–trigger semantic disconnect, revealing up to 26.06% cognitive memory accuracy where factual scores exceed 71.78%.

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THE PROBLEM

Cognitive Memory Collapses Under Cue–Trigger Disconnect (26.06% vs 71.78%)

LoCoMo-Plus shows that gemini-2.5-pro drops from 71.78 average factual accuracy on LoCoMo to only 26.06 on cognitive memory tasks.

Under this setting, long-term conversational agents fail to respect implicit state, goal, and value constraints, leading to behaviorally inconsistent and sometimes harmful responses.

HOW IT WORKS

LoCoMo-Plus Benchmark and Constraint-Consistency Framework

LoCoMo-Plus builds cognitive memory cases through Implicit Cue Dialogue Generation, Memory-Worthy Verification, Cue–Trigger Query Construction, Semantic Filtering, and Cue Memory Elicitation Validation before insertion into LoCoMo dialogues.

You can think of LoCoMo-Plus like a cognitive RAM plus a judge: cues write latent constraints, triggers read them back, and an LLM judge checks behavioral consistency.

This constraint-consistency mechanism lets LoCoMo-Plus test whether agents preserve and apply implicit constraints across long contexts, something a plain context window and string-matching metrics cannot reliably measure.

DIAGRAM

Cue–Trigger Interaction and Cognitive Constraint Checking

This diagram shows how LoCoMo-Plus models the interaction between user, agent, cue, trigger, and LLM judge during evaluation.

DIAGRAM

LoCoMo-Plus Construction and Evaluation Pipeline

This diagram shows the end-to-end LoCoMo-Plus pipeline from cue generation to constraint-consistency scoring.

PROCESS

How LoCoMo-Plus Handles a Cognitive Memory Instance

  1. 01

    Implicit Cue Dialogue Generation

    LoCoMo-Plus first uses Implicit Cue Dialogue Generation to create short dialogues that encode latent state, goal, preference, or value information.

  2. 02

    Memory-Worthy Verification

    In Memory-Worthy Verification, annotators filter cues to keep only persistent, behaviorally constraining information that truly benefits long-term conversational assistance.

  3. 03

    Cue–Trigger Query Construction

    Cue–Trigger Query Construction then generates underspecified trigger queries whose correct resolution depends on the cue while maintaining low semantic similarity.

  4. 04

    Semantic Filtering and Cue Memory Elicitation Validation

    Semantic Filtering removes shortcut pairs, and Cue Memory Elicitation Validation ensures each remaining instance genuinely requires recalling and applying the implicit cue.

KEY CONTRIBUTIONS

Key Contributions

  • 01

    LoCoMo-Plus Cognitive Memory Benchmark

    LoCoMo-Plus extends LoCoMo by adding cognitive memory QA instances decomposed into causal, state, goal, and value constraints, with gemini-2.5-pro scoring only 26.06% on this axis.

  • 02

    Constraint-Consistency Evaluation Framework

    LoCoMo-Plus replaces task-disclosed prompts and string-matching metrics with a unified conversational query and LLM-based constraint-consistency judging aligned with implicit memory use.

  • 03

    Empirical Analysis of Memory and Metric Biases

    LoCoMo-Plus empirically shows prompt bias, length bias, and rapid cognitive memory collapse, including PDR dropping to 5.88% and RTR to 18% for cognitive cases as context grows.

RESULTS

By the Numbers

LoCoMo average

71.78%

+26.06 over LoCoMo-Plus cognitive accuracy for gemini-2.5-pro

LoCoMo-Plus cognitive

26.06%

vs gemini-2.5-pro factual average of 71.78% on LoCoMo

Object memory PDR

92.85%

high precision drop rate for object memory under increasing dialogue length

Cognitive memory PDR

5.88%

rapid collapse of cognitive memory compared to 67.39% episodic PDR

LoCoMo-Plus is evaluated alongside LoCoMo, where LoCoMo tests factual memory and LoCoMo-Plus tests cognitive memory under cue–trigger semantic disconnect. These numbers show that LoCoMo-Plus exposes a large gap between robust factual recall and fragile cognitive constraint preservation.

BENCHMARK

By the Numbers

LoCoMo-Plus is evaluated alongside LoCoMo, where LoCoMo tests factual memory and LoCoMo-Plus tests cognitive memory under cue–trigger semantic disconnect. These numbers show that LoCoMo-Plus exposes a large gap between robust factual recall and fragile cognitive constraint preservation.

BENCHMARK

Overall performance of models and memory systems on LoCoMo and LoCoMo-Plus

Average accuracy on LoCoMo (factual memory) versus LoCoMo-Plus (cognitive memory) for selected systems.

BENCHMARK

Cognitive memory performance on LoCoMo-Plus (Gap column)

Accuracy on LoCoMo-Plus cognitive memory tasks for selected systems, showing the performance drop from factual LoCoMo.

KEY INSIGHT

The Counterintuitive Finding

Even the strongest system, gemini-2.5-pro, achieves 71.78% average accuracy on LoCoMo but only 26.06% on LoCoMo-Plus cognitive memory tasks.

This is surprising because developers often assume that better long-context factual recall automatically yields strong cognitive memory, but LoCoMo-Plus shows these abilities can diverge sharply.

WHY IT MATTERS

What this unlocks for the field

LoCoMo-Plus unlocks a way to stress-test agents on implicit constraint preservation, not just explicit fact retrieval, using realistic cue–trigger disconnects.

Builders can now design and compare memory architectures that explicitly target cognitive behaviors like respecting user goals and values over time, which was previously impractical to measure.

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