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Learning as the Unsupervised Alignment of Conceptual Systems

Brett D. Roads, Bradley C. Love

arXiv:1906.09012v3cs.LGstat.ML

TL;DR

Learning object labels from noisy experience raises the question of whether conceptual systems can be aligned without supervision. The paper uses algorithm-agnostic computational experiments to test alignment across systems, finding that mapping-structure correlations strengthen as concept sets grow.

  • Problem

    The study asks whether distinct conceptual systems can be aligned without supervision and how concept and system counts affect alignment.

    Source: Methods · p. 13
  • Method

    Algorithm-agnostic computational experiments test alignment across conceptual systems, examining relational signatures, concept and system counts, and human word acquisition.

    Source: Discussion · p. 12, Methods · p. 13
  • Results

    ρ increased from .16 (10 concepts) to .98 (300 concepts; both p < .01), and adding systems or focusing on earliest-acquired words especially boosted alignment in smaller sets.

    Source: Results · pp. 7, 9, 10
  • Takeaways & Limitations

    Aligning whole conceptual systems may support low-shot or zero-shot learning, rather than treating each system as an isolated learning problem.

    Source: Discussion · p. 12

    Most analyses used embedding spaces that relied on annotated data rather than raw images.

    Source: Discussion · p. 13

Abstract

from arXiv · show

Concept induction requires the extraction and naming of concepts from noisy perceptual experience. For supervised approaches, as the number of concepts grows, so does the number of required training examples. Philosophers, psychologists, and computer scientists, have long recognized that children can learn to label objects without being explicitly taught. In a series of computational experiments, we highlight how information in the environment can be used to build and align conceptual systems. Unlike supervised learning, the learning problem becomes easier the more concepts and systems there are to master. The key insight is that each concept has a unique signature within one conceptual system (e.g., images) that is recapitulated in other systems (e.g., text or audio). As predicted, children's early concepts form readily aligned systems.

Results

Across text, image, and audio systems, alignment correlation tracked mapping accuracy, and larger conceptual systems made correct mappings more distinguishable. Adding systems, accounting for noisy embeddings, and restricting concepts to early-acquired ones improved alignment strength, especially in small systems.

  • Alignment correlations tracked mapping accuracy across text–image (ρ = .99), text–audio (ρ = .92), and image–audio (ρ = .92) scenarios.Each correlation was significant at p < .01.Source: Results · p. 7, Figure 3 · p. 8
  • For 10, 30, 100, and 300 concepts, mapping-accuracy correlations rose from ρ = .16 to .67, .96, and .98, respectively.Smaller systems have weaker concept signatures, making misleading high-correlation mappings more likely.Source: Results · p. 7, Figure 3 · p. 8
  • Alignment strength was low in few-concept scenarios and high in many-concept scenarios, while structural deviations could make incorrect mappings score above the correct mapping.For example, a fox–rabbit switch between word and image embeddings could lead to an erroneous match.Source: Results · pp. 7, 9, Figure 3 · p. 8
  • Within-group misalignments reduced alignment correlation by 0.16% on average, versus 1.31% for across-group errors, an roughly eight-fold difference.Source: Results · p. 9
  • At 10 concepts, three-system alignment strength was M = 0.61, SD = 0.08 versus two-system M = 0.50, SD = 0.10; gains remained significant through 59 concepts.At 59 concepts, the respective strengths were M = 0.954, SD = 0.001 and M = 0.945, SD = 0.002.Source: Results · pp. 9–10
  • With a noisy image embedding, alignment strength fell from approximately .99 to .85, then recovered to approximately .95 after five noisy image embeddings were included.Source: Results · p. 10
  • For the smallest concept subset, age-of-acquisition-constrained alignment strength was M = 0.65, SD = 0.14 versus unconstrained M = 0.53, SD = 0.09.Using earliest-acquired concepts improved alignment strength particularly in systems with few concepts.Source: Results · p. 10

Discussion

Unsupervised learning can align whole conceptual systems because concepts have distinctive relational signatures mirrored across modalities. More concepts make these relationships more distinctive, while adding systems or focusing on early-acquired words can help alignment when few concepts are available.

Discussion

  • Each concept’s unique signature in one system is mirrored in others, allowing shared experience across modalities to link whole conceptual systems and potentially support low-shot or zero-shot learning.This perspective contrasts with learning isolated systems and with unsupervised approaches that fail to bridge different systems.Source: Discussion · pp. 10, 12
  • As the number of concepts increases, alignment correlation tracks mapping accuracy more closely, and structural relationships favor mostly correct mappings and sensible within-group mistakes.In many-concept scenarios, these relationships may provide a strong prior that reduces the need for supervised learning; the pattern may also contribute to some children’s vocabulary spurt (33).Source: Discussion · p. 12
  • Alignment struggles with very few concepts, but can improve by linking more than two systems or restricting analysis to words acquired earliest in life.A concept such as “Toothbrush” is alignable through its relationships to other early words, not necessarily on its own; equally similar concepts provide no structure to resolve ambiguity.Source: Figure 4 · p. 11, Discussion · p. 12
  • Distinctive relationships may help explain early word acquisition and cross-modal learning, though caregivers may also curate interactions to favor less ambiguous systems (34).The authors also suggest that alignable concepts may be experienced more often, that noun structure may partly explain children’s early basic-level nouns (35–37), and that alignment may help explain infant benefits from multiple modalities (38).Source: Discussion · pp. 12–13
  • Most analyses used annotated embeddings; pixel-only DeepCluster embeddings nevertheless achieved relatively high alignment strength with text, while efficient search across possible alignments remains a challenge.The authors anticipate improved alignment from unsupervised embedding extraction and suggest search algorithms using basic cognitive constraints to approximate an optimal mapping (39,40), as analogy models align individual concepts (41–43).Source: Discussion · p. 13

Methods

The study uses an algorithm-agnostic approach to test whether conceptual systems can be aligned without supervision and how alignment varies with the number of concepts and systems, in comparison with human word acquisition.

Methods

  • The study tests unsupervised alignment across conceptual systems, how alignment varies with the number of concepts and systems, and how it compares with human word acquisition.The approach is intended to reveal theoretical properties of system alignment rather than the capabilities of a particular alignment algorithm.Source: Methods · p. 13

Assembling Conceptual Systems via Co-occurrence Embeddings

  • Applying GloVe to domain-specific co-occurrence statistics yields text, image, and audio conceptual systems; image classes in one image and audio classes in one file count equally, without distance weighting.The image and audio embeddings are 50-dimensional and derived from Open Images V4 and AudioSet, respectively.Source: Assembling Conceptual Systems via… · pp. 14–16

Assembling Conceptual Systems via Deep Neural Network Embeddings

  • A pretrained VGG-16/DeepCluster model provides 4096-dimensional image features, with 25 ImageNet systems assembled by randomly selecting one image per class.Each system uses a different random sample of image encodings.Source: Assembling Conceptual Systems via Deep… · p. 16

Aligning Conceptual Systems

  • Alignment scenarios compare two or more systems or use word age-of-acquisition data, restricting analysis to each scenario’s shared single-word concepts.Multiword labels are dropped from OpenImages, AudioSet, and age-of-acquisition data; ImageNet descriptions are manually converted to single-word tokens.Source: Aligning Conceptual Systems · p. 16

Alignment Strength

  • Alignment-strength analyses use repeated random subsets that leave five intersecting concepts unused in each run.For example, runs sample 59 of the 64 concepts shared by text, image, and audio systems.Source: Alignment Strength · p. 17

Computing Mapping Accuracy and Alignment Correlation

  • For two systems, mapping accuracy counts correct concept matches and correlation is Spearman’s correlation between their similarity matrices; for more systems, accuracy requires an all-system match and correlations are averaged across system pairs.In multi-system scenarios, incorrect cross-system matches receive no partial credit.Source: Computing Mapping Accuracy and… · p. 17
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