Cause of Replacement Behavior in the Add-100-Fruits Task

Ascertain whether the behavior of Nano Banana Pro replacing existing fruits instead of adding a new fruit during the "add-100-fruits" iterative editing run on the Table image is caused by the model skipping examination of some existing fruits during its internal reasoning process.

Background

In the object-level evaluation, the authors used the Table image and prompted Nano Banana Pro to add 100 different fruits over 100 steps (the "add-100-fruits" run). Instead of consistently adding a new fruit each step, the model sometimes replaced an existing fruit with the newly requested fruit, violating the instruction semantics.

Inspection of the model’s reasoning summary suggested it may not exhaustively check all existing fruits on the table before generation. However, because only a summarized reasoning trace is exposed by the API, the authors could not determine whether this incomplete checking directly caused the replacement behavior, leaving the causal mechanism unresolved.

References

The reasoning summary showed that the model did not exhaustively examine each of the existing fruits on the table. Since the full reasoning trace is not visible, we cannot confirm whether skipping some fruits during reasoning caused this replacement issue.

— Banana100: Breaking NR-IQA Metrics by 100 Iterative Image Replications with Nano Banana Pro  (2604.03400 - Tang et al., 3 Apr 2026) in Section 3.2 (Object-Level Failure Modes), Replacement but not Addition