Verbs,time, and modality

In the first part of this paper it is argued that Vendler's classification of verbs into aspectual categories, called activities, accomplishments, achievements, and states, is better seen as classifying the meanings of sentences, and a recursive scheme for describing the aspectual character of sentences is presented. In the second part, this scheme is applied to the discussion of the epistemic and deontic meanings of the modal verbs must, will, and may. In particular, the relation between the “future” and “nonfuture” senses of epistemic will is examined.     

Putting knowledge in its place: A scheme for programming parallel processing structures on the fly

This paper introduces a mechanism called CID, the Connection Information Distributor. CID extends connectionism by providing a way to program networks of simple processing elements on line, in response to processing demands. Without CID, simultaneous processing of several patterns has only been possible by prewiring multiple copies of the network needed to process one pattern at a time. With CID, programmable processing structures can be loaded with connection information stored centrally, as needed. To illustrate some of the characteristics of the scheme, a CID version of the interactive activation model of word recognition is described. The model has a single permanent representation of the connection information required for word perception, but it allows several words to be processed simultaneously in separate programmable networks. Multiword processing is not perfect, however. The model produces the same kinds of intrusion errors that human subjects make in processing brief presentations of word-pairs, such as SAND LANE (SAND is often misreported as LAND or SANE). The resource requirements of the mechanism, in terms of nodes and connections, are found to be quite moderate, primarily because networks that are programmed in response to task demands can be much smaller than networks that have knowledge of large numbers of patterns built in.     

Motor and cognitive interference effects on unimanual tapping rates

Experiments conducted on both normal and disordered populations have led to the hypothesis that the left hemisphere's specialization for language results from its control over motor activities. This control is reflected in the lateralized disruption of manual activity during cerebral time-sharing tasks. Recent studies have challenged this hypothesis, stating that the interference effects reflect both cognitive and motor mechanisms in the left hemisphere. This experiment investigates whether the left hemisphere's control over speech involves both of these components or is purely motor. The question was examined by measuring the effect of concurrent hemispheric activity on single-finger tapping rates. Forty subjects tapped under two conditions: speaking and listening. The data show there may be both motor and cognitive mechanisms involved in left-hemisphere control.     

Identifying the relevant aspects of a problem text

Forty-nine subjects judged the relevancy of sentence parts of a word problem (the Allsports problem). Patterns of subjects' judgments suggest three problem-solving heuristics: a SETS heuristic, a TIME heuristic, and a QUESTION heuristic. Presentation of the question before the problem tends to suppress SETS and TIME heuristics. A computer program (ATTEND) is presented to simulate subjects' behavior on the Allsports problem. The program is context-sensitive in that it can change a relevance judgment upon the acquisition of further information. Averaged subject judgments and ATTEND judgments agree for 87% of the items.