Analogical reasoning is identifying relationships between two things and mapping those relationships onto novel pairs. Computational approaches often model analogical reasoning using vector-based word embeddings, where relational similarity is represe...
Analogical reasoning is identifying relationships between two things and mapping those relationships onto novel pairs. Computational approaches often model analogical reasoning using vector-based word embeddings, where relational similarity is represented geometrically. A key example is the parallelogram model, which assumes that relationships between word pairs can be captured as vector differences. These models assume that relational similarity follows geometric constraints such as triangle inequality, which in mathematics means that the sum of any two sides of a triangle is greater than or equal to the third side. In analogy, if A is similar to B and B to C, then A should be similar to C. However, such models assume a pair’s similarity is stable and context-independent. We hypothesized that when there are two types of relationships for one pair, it would lead to context-dependent violations of the triangle inequality and challenge the assumptions of vector-based models. To investigate this, we developed an analogy task where participants revealed four masked images one by one through fixation and then rated the similarity between pairs. We created 18 questions, each of four pairs of related items labeled A, B, C, and D. Pairs AB, AC, and BC share the same relation; pair AD has a different relation, while pairs BD and CD have no meaningful relation. This configuration formed two comparison triangles: one with AB, AC, BC, and another with AB, AD, and BD. This enabled us to test whether relational similarity judgements followed the triangle inequality within a consistent relation, and whether that pattern was violated when a different relation was introduced. Human behavior confirmed that the triangle inequality was often violated in the mixed-relation triangle but preserved in the consistent-relation triangle. These findings suggest that human relational similarity judgements are context-sensitive. To test whether this effect depended on semantic meaning, a second experiment used geometric stimuli defined by visual features as shape, edge color, and fill color. Violations occurred more frequently when pair A shared two features (same shape and same fill color), while B and C shared only the fill color, and D shared only the shape. This suggests that humans selectively emphasize one relational dimension at a time, compressing multi-feature information possibly due to attentional limits or prioritization. Furthermore, when the same questions were tested on large language models, there were slightly fewer violations in the main experiment and minimal violations in the control task. These results suggest that, unlike humans, the large language models might maintain access to all relational dimensions, leading to no feature compression.