Factors Related to the Long-Term Course of PTSD in Older Ex–Prisoners of War

This study examined relationships between socioenvironmental factors occurring in later-life and current and changing PTSD symptom levels in a sample of 177 community-dwelling World War II and Korean era ex–prisoners of war. Factors examined included negative life events, negative health events, social support, and death acceptance. PTSD was assessed at Time 1. PTSD and the later-life factors were then assessed 4 years later (Time 2). Cross-sectional analysis examined the relationship of the later-life factors to current PTSD symptomatology. Longitudinal analysis examined their relationship to changing PTSD symptomatology over the 4-year interval. Negative health changes, social support, and death acceptance were significantly related to current and changing PTSD symptomatology, but negative life events were not. The authors conclude that health and psychosocial factors that may occur in later-life can be related to PTSD symptom levels even many decades after a traumatic experience.     

Parallel structure: A source of facilitation in sentence comprehension

Reading time for the second clause of a conjoined sentence was found to be faster when the clause was structurally similar to the first clause than when the clausal structures differed. This “parallel structure” effect was found for each of several types of structures, including active versus passive constructions, direct object versus sentential complement (minimal vs. nonminimal attachment), nonshifted versus shifted heavy noun phrase, agent versus theme, and animate versus inanimate noun phrase. The pervasiveness of the effect ruled out some hypotheses about its basis, including the hypothesis that it would occur only when a subject’s just having processed a structure would affect how temporary ambiguities are resolved. Detailed analysis of the data suggested the existence of several distinct sources of the effect and provided indirect evidence that people typically compute both a surface structure and an S-structure representation of a sentence.     

Filling gaps: Decision principles and structure in sentence comprehension

The correct grammatical characterization of sentences containing filler-gap dependencies is a topic of considerable theoretical interest in linguistics. In some grammatical frameworks, these dependencies are representef in terms of conditions on the permissible indexing of structures (or alternative structure evaluation conditions) which a representation must adhere to in order to be well-formed. In other frameworks, constraints on permissible filler-gap dependencies are simply inherent in the set of phrase structure rules contained in the grammar of a language.The processing of sentences with multiple (potential) filler-gap dependencies was investigated in two experiments. The first experiment provided evidence for three claims. First, the human sentence processor abides by a strategy of assigning the most recent potential filler to a gap. Hence, ‘recent filler’ sentences where this assignment proves to be correct takes less time to comprehend than ‘distant filler’ sentences where this decision turns out to be incorrect. Second, the recent filler strategy is itself just a special case of a more general strategy of assigning the most salient potential filler to a gap. Third, unambiguous sentences in which a filler-gap assignment is disambiguated by ‘control’ information specified by individual verbs gives rise to the same recent filler errors as ambiguous sentences. This suggests that tentative filler-gap assignments are made by the processor before all of the relevant constraints on permissible filler-gap dependencies are consulted by the processor.The second experiment tested an alternative hypothesis that the more complex ‘distant filler’ sentences took longer to comprehend in the first experiment only because these sentences often contained verbs which license two adjacent gaps. The experiment showed that there was a significant recent filler effect in sentences that did not contain adjacent gaps and that this effect did not interact with verb class.The finding that the processor delays use of verb-control information is extremely surprising. It may be explained by the fact that this information is only relevant to one type of gap (‘equi-gaps’) and what type of gap the processor is dealing with often can not be determined unambiguously at the time when it initially encounters a gap in its left-to-right processing of a sentence.If our interpretation of these findings is correct, they argue for a considerable amount of structure in the sentence comprehension system. Further, they favor a view of sentence processing in which processing operations involving constraints on the permissible indexing (or evaluation) of structures lag behind the processor's structure building operations. Hence, the results favor those grammatical theories which preserve this distinction over grammatical theories which provide a uniform characterization of all syntactic well-formedness conditions.     

Relational and absolute cues in auditory discrimination by monkeys

Rhesus monkeys were trained to make auditory frequency, intensity, and duration discriminations. Initial training was carried out with a procedure which allowed the utilization of either relational cues or absolute cues. Later tests with similar auditory parameters allowed only the utilization of relational cues. Performance on these latter tests indicated that relational rather than absolute cues had been utilized when both types were available on the frequency and intensity discrimination tasks. However, absolute rather than relational cues were apparently utilized in making duration discriminations.     

The use of syntactic information in filling gaps

Two sentence-comprehension time experiments replicated and extended previously reported research indicating that readers initially make a quick, heuristic assignment of fillers to gaps in temporarily ambiguous sentences such as “Who did John beg to sing?” and “Who did John beg to sing for?” The Most Recent Filler heuristic readers seemed to adopt made the former “distant filler” sentence harder to comprehend than the latter “recent filler” sentence. Readers did not in general use all available sources of information in making this assignment. In particular, they usually delayed their use of verb control information so that substituting the unambiguous-control verbs “force” or “begin” for “beg” did not eliminate the distant filler inferiority. the experiments counter some criticisms that have been made of the previously reported research. The possibility that readers delay using an interesting natural category of information was raised, and its implications for the mental grammar were considered.     

The sausage machine: A new two-stage parsing model

It is proposed that the human sentence parsing device assigns phrase structure to word strings in two steps. The first stage parser assigns lexical and phrasal nodes to substrings of roughly six words. The second stage parser then adds higher nodes to link these phrasal packages together into a complete phrase marker.This model of the parser is compared with ATN models, and with the two-stage models of Kimball (1973) and Fodor, Bever and Garrett (1974). Our assumption that the units which are shunted from the first stage to the second stage are defined by their length, rather than by their syntactic type, explains the effects of constituent length on perceptual complexity in center embedded sentences and in sentences of the kind that fall under Kimball's principle of Right Association. The particular division of labor between the two parsing units allows us to explain, without appeal to any ad hoc parsing strategies, why the parser makes certain ‘shortsighted’ errors even though, in general, it is able to make intelligent use of all the information that is available to it.     

Constraint satisfaction as a theory of sentence processing

Various problems with the constraint satisfaction model are discussed. It is argued that the empirical evidence presented in support of the model does not concern predictions of the model that diverge from those of depth-first (one analysis at a time) models. Several methodological problems are also noted. As a theory of sentence processing, the model is inadequate. It fails to account for the assignment of local structure, global structure, structure involving discontinuous dependencies, long-distance dependencies, and adjunct phrases. It makes incorrect predictions about the timing of syntactic analysis. Further, because syntactic structure is available only through activation of syntactic projections stored in the lexical entry of words, the model leaves entirely unexplained the myriad psycholinguistic findings demonstrating independence of lexical and syntactic structure (in Event Related Potential studies, code-switching, pure syntactic priming, etc). Finally, the model is not restrictive or explanatory, providing an account that largely consists ofpost hoc correlations between frequency counts or subjects ratings of sentences and processing time data for the same sentences.The present paper is an excerpt from Sentence (Re-)Analysis presented at the 1994 CUNY Conference. It was supported by NIH Grant HD18708 to Clifton and Frazier and DBS9121375 to Rayner and Frazier. I am very grateful to Chuck Clifton and to an anonymous reviewer for comments on an earlier draft of this paper.     

Size and reliability of frequency-difference thresholds determined with operant tracking procedure

Auditory frequency discrimination thresholds have been determined by a “tracking procedure” at five frequencies and two intensity levels for a group of four cats. Intra-animal thresholds were found to be quite stable, and there was good inter-animal agreement among three of the four cats. Although quite stable, the tracking thresholds were larger than those which had been obtained using an avoidance procedure. However, because of the several differences between the tracking procedure and avoidance conditioning procedure, no conclusions can be drawn concerning the efficacy of the different types of reinforcement in determining the ultimate limit of the animals' discrimination ability.