Lexical decision in sentences: Effects of syntactic structure

A lexical decision paradigm was used to examine syntactic influence on word recognition in sentences. Initial fragments of sentences were presented visually (CRT display) one word at a time (at reading speeds), from left to right. The string terminated with the appearance of a lexical decision target. The grammatical structure of the incomplete sentence affected lexical decision reaction time (RT). In Experiment 1, modal verb contexts followed by main verb targets and preposition contexts followed by noun targets produced lower RTs than did the opposite pairings (i.e., modal/noun and preposition/verb). In Experiment 2, transitive verb contexts followed by noun targets and subject noun phrase contexts followed by verb targets yielded lower RTs than did the opposite pairings. Similar contrasts for adjective targets did not yield comparable effects in Experiment 2, but did when the adjective was the head of a predictable phrase (Experiment 4). In Experiment 3, noun targets yielded lower RTs than did verb targets after contexts of a transitive verb followed by a prepositional phrase. An account of these effects is offered in terms of parsing constraints on phrasal categories.     

Evidence for alternative strategies of sentence retention

Measurements of pupil size were taken while subjects listened to sentences and either tried to repeat them (R) or answered a question about them (QuA), after either a 3 or 7 sec retention interval. Pupil dilations were larger for R than for QuA, both towards the end of presentation and during the retention interval. Similar results were obtained by Kahneman and Wright (1971) when comparing total and partial recall of word lists. They attributed the differences in pupil dilations to differences in rehearsal strategy. However, the interaction between recall condition and retention interval was less convincing with sentential material, and an alternative explanation is suggested in terms of the level of abstraction at which the sentences are processed. This interpretation is supported by other evidence relating to the existence of alternative sentence retention strategies.

Pupil dilations failed to reveal phrase juncture phenomena, although two levels of ambient illumination were used in the hope of detecting such effects. In a modified question condition (QuB), where the question was given before the sentence, pupil dilations varied as a function of the part of the sentence providing the answer. These data indicated that people did not begin to frame their answer until they encountered in the sentence those words used in the question.     

CROSS-MODAL TRANSFER AND SENSORY EQUIVALENCE

Recent studies of cross-modal matching and transfer in animals and human subjects are reviewed and some problems concerning the design of experiments to study these phenomena discussed. Attempts to account for cross-modal effects are evaluated and the concept of sensory equivalence briefly examined.     

A developmental study of schedule-induced polydipsia in the rat

Rats 30, 60, 90, and 120 days of age were fed 105 45-mg food pellets on a noncontingent VT 70-sec schedule during 14 daily 2-hr sessions. Every animal became polydipsic on this schedule when compared with a schedule in which 105 pellets were presented at the beginning of the session. Mean polydipsic ratios (schedule intake/control intake) ranged from 2.9–5.4. Water intakes (milliliters per 100g body weight) did not differ during the last five sessions as a function of age. The results are discussed with respect to the generality of the class of adjunctive behaviors.     

Relative preference for external and self-controlled reinforcement in monkeys

Monkeys were tested for their relative preference for self-monitored and externally imposed systems of reinforcement. One monkey clearly preferred to self-reward his own performances. whereas a second monkey favored slightly the externally administered system but displayed a small gradual shift toward self-reward as the sessions progressed. Unlike previous findings. unmerited self-reward did not result in rapid discarding of self-imposed performance requirements. The level of work output and the interactive effects of multiple reinforcement control are possible operative factors in sustaining self-imposed contingencies long after punishment for unmerited self-reward has been discontinued.