Making Probabilistic Relational Categories Learnable

Theories of relational concept acquisition (e.g., schema induction) based on structured intersection discovery predict that relational concepts with a probabilistic (i.e., family resemblance) structure ought to be extremely difficult to learn. We report four experiments testing this prediction by investigating conditions hypothesized to facilitate the learning of such categories. Experiment 1 showed that changing the task from a category‐learning task to choosing the “winning” object in each stimulus greatly facilitated participants' ability to learn probabilistic relational categories. Experiments 2 and 3 further investigated the mechanisms underlying this “who's winning” effect. Experiment 4 replicated and generalized the “who's winning” effect with more natural stimuli. Together, our findings suggest that people learn relational concepts by a process of intersection discovery akin to schema induction, and that any task that encourages people to discover a higher order relation that remains invariant over members of a category will facilitate the learning of putatively probabilistic relational concepts.     

Spectral factors in the perception of vowel quantity in Icelandic

Previous research has shown that the ratio of vowel to rhyme (vowel + consonant) duration is a major cue for quantity in Icelandic. In particular it serves as a higher-order invariant which enables the listener to disentangle those durational transformations of the speech signal which are "extrinsic" (e. g. due to changes in speaking rate) from those which are "intrinsic" to the phonemic message, involving a change of phonemic quantity. Previous research has been based on speech segment contrasts which are purely durational, involving vowels with a uniform spectrum whether phonemically long or short, such as [a] or [I]. This paper looks at the role of spectral factors in vowels which are spectrally dissimilar in their long and short varieties. It is shown that in these cases the spectral differences can be sufficiently great to override the previously established relational invariant for quantity. The implications of this finding for a model of quantity perception are discussed.     

Representation and aspectual shape

One of the most significant characteristics of intentional states is the fact that they represent their intentional objects under selective aspects (or modes of presentation); that is, that they manifest an aspectual shape (Searle, 1992). Surprisingly however, although this remarkable feature is widely recognized little has been done to explain what makes representation aspect-relative in the first-place. In this article I attempt to outline an answer to this question. I begin with a critique of Searle's explanation of aspectual shape as anchored in conscious experience. I argue next that, since to represent an object under an aspect is to represent it relative to a selective set of properties, the task - from the perspective of a theory of mental representation - is to explain what makes intentional states property-relative. It is then argued that while this task cannot be handled properly by standard (in particular computational-representational) theories of mental representation, a shift towards an action-based framework for theories of perception and representation promises to provide the key with which to unlock the puzzle.