Features of the Expert-System-Shell SPIRIT

The inference process in a probabilistic and conditional environmentunder minimum relative entropy, permits the acquisition of basicknowledge, the consideration of - even uncertain - ad hoc knowledge,and the response to queries. Even if these procedures are wellknown in the relevant literature their realisation for large-scaleapplications needs a sophisticated tool, allowing the communicationwith the user as well as all relevant logical transformationsand numerical calculations. SPIRIT is an Expert-System-Shellfor these purposes. Even for hundreds of – consistent– facts about the involved variables’ dependenciesthe shell automatically generates the corresponding epistemicstate, thus permitting the derivation of conclusions from theacquired knowledge. These conclusions’ reliability orprecision can be checked, inviting the user to enrich the knowledgeby further facts, if desired. Any inconsistencies among providedfacts are detected, and their elimination will be supportedby the shell. Knowledge acquisition can come from provided factsby a knowledge engineer as well as from real world data; inductivelearning supports the use of such data. An important capabilityof the shell is the calculation of impacts upon ideas or conceptsfrom a given stimulus. This paper is a brief survey of theoreticalconcepts and the corresponding features of the system, whichare accompanied by illustrative examples.     

Language Acquisition is Language Change

According to the theory of Universal Grammar, the primary linguistic data guides children through an innately specified space of hypotheses. On this view, similarities between child-English and adult-German are as unsurprising as similarities between cousins who have never met. By contrast, experience-based approaches to language acquisition contend that child language matches the input, with nonadult forms being simply less articulated versions of the forms produced by adults. This paper reports several studies that provide support for the theory of Universal grammar, and resist explanation on experience-based accounts. Two studies investigate English-speaking children’s productions, and a third examines the interpretation of sentences by Japanese speaking children. When considered against the input children are exposed to, the findings of these and other studies are consistent with the continuity hypothesis, which supposes that child language can differ from the language spoken by adults only in ways that adult languages can differ from each other.     

Story Recall and Narrative Coherence of High-Functioning Children with Autism Spectrum Disorders

Previous research has found few quantitative differences between children with high-functioning autism spectrum disorders (ASDs) and well-matched controls in the length, complexity, and structure of their narratives. Researchers have noted, however, that narratives of children with ASDs have an unusual and idiosyncratic nature. This study provides an analysis of narratives in 17 children with high-functioning ASDs and 17 typically developing children matched on age, gender, language abilities, and cognitive abilities. We examined story recall and narrative coherence. The study revealed no group differences in story length or syntactic complexity. Children with ASDs also did not differ from controls in their use of the gist of a story to aid recall, or in their sensitivity to the importance of story events. Children with ASDs did, however, produce narratives that were significantly less coherent than the narratives of controls. Children with ASDs appeared less likely to use the gist of the story to organize their narratives coherently. These findings are discussed with regard to their relationship to other cognitive and linguistic difficulties of children with ASDs.     

The acquisition of allophonic rules: statistical learning with linguistic constraints

Phonological rules relate surface phonetic word forms to abstract underlying forms that are stored in the lexicon. Infants must thus acquire these rules in order to infer the abstract representation of words. We implement a statistical learning algorithm for the acquisition of one type of rule, namely allophony, which introduces context-sensitive phonetic variants of phonemes. This algorithm is based on the observation that different realizations of a single phoneme typically do not appear in the same contexts (ideally, they have complementary distributions). In particular, it measures the discrepancies in context probabilities for each pair of phonetic segments. In Experiment 1, we test the algorithm's performances on a pseudo-language and show that it is robust to statistical noise due to sampling and coding errors, and to non-systematic rule application. In Experiment 2, we show that a natural corpus of semiphonetically transcribed child-directed speech in French presents a very large number of near-complementary distributions that do not correspond to existing allophonic rules. These spurious allophonic rules can be eliminated by a linguistically motivated filtering mechanism based on a phonetic representation of segments. We discuss the role of a priori linguistic knowledge in the statistical learning of phonology.     

The Logic and Meaning of Plurals. Part II

In this sequel to “The logic and meaning of plurals. Part I”, I continue to present an account of logic and language that acknowledges limitations of singular constructions of natural languages and recognizes plural constructions as their peers. To this end, I present a non-reductive account of plural constructions that results from the conception of plurals as devices for talking about the many. In this paper, I give an informal semantics of plurals, formulate a formal characterization of truth for the regimented languages that results from augmenting elementary languages with refinements of basic plural constructions of natural languages, and account for the logic of plural constructions by characterizing the logic of those regimented languages.

Rapid acquisition in concurrent chains: evidence for a decision model

Pigeons' choice in concurrent chains can adapt to rapidly changing contingencies. Grace, Bragason, and McLean (2003) found that relative initial-link response rate was sensitive to the immediacy ratio in the current session when one of the terminal-link fixed-interval schedules was changed daily according to a pseudorandom binary sequence (e.g., Schofield & Davison, 1997). The present experiment tested whether the degree of variation in delays across sessions had any effect on acquisition rate in Grace et al.'s (2003) rapid-acquisition procedure. In one condition ("minimal variation"), the left terminal link was always fixed-interval 8 s and the right terminal link was either fixed-interval 4 s or fixed-interval 16 s. In the other condition ("maximal variation"), a unique pair of fixed-interval values was used in each session. Responding was sensitive to the current-session immediacy ratio in both conditions, but across subjects there was no systematic difference in sensitivity. These results challenge the view that initial-link responding in the rapid-acquisition procedure is determined by changes in the learned value of the terminal-link stimuli, and suggests instead that a process resembling categorical discrimination may control performance. A decision model based on the assumption that delays are categorized as short or long relative to the history of delays provided a good account of the data and shows promise in being able to explain other choice phenomena.     

Derived manding in children with autism: synthesizing Skinner's verbal behavior with relational frame theory

Mand functions for two stimuli (A1 and A2) were trained for 3 children with autism and were then incorporated into two related conditional discriminations (A1-B1/A2 -B2 and B1-C1/B2-C2). Tests were conducted to probe for a derived transfer of mand response functions from A1 and A2 to C1 and C2, respectively. When 1 participant failed to demonstrate derived transfer of mand response functions, transfer training using exemplars was conducted. When participants had demonstrated derived transfer of mand functions, the X1 and X2 tokens that were employed as reinforcers for mand responses were incorporated into two conditional discriminations (X1-Y1/X2-Y2 and Y1-Z1/Y2-Z2). Tests were conducted for derived transfer of reinforcing functions. Finally, tests were conducted to determine if the participants would demonstrate derived manding for the derived reinforcers (present C1 and C2 to mand for Z1 and Z2, respectively). Derived transfer of functions was observed when the sequence of training and testing was reversed (i.e., training and testing reinforcing functions before mand response functions) and when only minimal instructions were provided.     

Three-month-olds' visual preference for faces and its underlying visual processing mechanisms

This study was aimed at investigating the face preference phenomenon and its underlying mechanisms at 3 months of age. Using an eye-tracker apparatus, Experiment 1 demonstrated that 3-month-olds prefer natural face images to unnatural ones, replicating and extending previous evidence obtained with schematic facelike stimuli. Experiments 2 and 3 showed that the general mechanisms that induce face preference in newborns could not explain the same phenomenon at 3 months of age, when infants are attracted by perceptual cues more specific to faces. This suggests that signs of a process of cognitive specialization are already present in 3-month-olds' visual behavior toward faces.     

Acquisition of cocaine self-administration with unsignaled delayed reinforcement in rhesus monkeys

Six experimentally naive rhesus monkeys produced 0.01 mg/kg/infusion cocaine by lever pressing under a tandem fixed-ratio 1 differential-reinforcement-of-other-behavior schedule. One lever press initiated an unsignaled 15- or 30-s delay culminating in cocaine delivery. Each press made during the delay reset the delay interval. With two exceptions, responding was acquired and maintained at higher rates than responding on a second (inoperative) lever. For the exceptions, a cancellation contingency was arranged in which each formerly inoperative-lever response reset the tandem schedule. This manipulation reduced presses on the inoperative lever. Subsequently, the consequences of responding on the two levers were reversed, and the monkeys again responded at higher rates on the operative lever. As a comparison, 3 additional experimentally naive monkeys received response-independent cocaine deliveries. Although lever pressing was observed, it extinguished and was subsequently reestablished under the tandem schedule. The results suggest that although response-reinforcer contiguity is not required for cocaine to acquire reinforcing functions, a response-reinforcer relation appears necessary.     

Variations in Figurative Language Use as a Function of Mode of Communication

Various studies have demonstrated that the mode by which people communicate affects the content of their messages. The present study examines the ways in which one aspect of language use, namely figurative language, differs as a function of mode of communication. Subjects worked together in pairs to build a small household appliance, with an expert directing a novice in the construction. Subjects communicated in one of four modes: full copresence, separated by a screen, through an intercom system, or through e-mail. Differences between modes were found on a number of measures of figurative language types, including what the author has described as interrogative analogies. These differences are discussed in terms of costs, constraints, and affordances associated with different media, and the role figurative language plays in communication.