Frequency judgements: the problem of defining a perceptual event

In four experiments the conditions under which frequency judgments reflect the relative frequency of complex perceptual events were explored. Subjects viewed a series of 4 x 4 grids each containing seven items, which were letters and numbers in one of four typefaces. Later judgments of the relative frequency with which particular letters appeared in particular typefaces were unaffected by a warning about an upcoming frequency judgment task, but were affected by both the time available for processing the stimuli and the nature of the cover task subjects engaged in while viewing the grids. Frequency judgments were poor when exposure durations were less than 2 s and when the cover task directed subjects' attention merely to the locations of the items within the grids. Frequency judgments improved when the cover task directed subjects' attention to the identity of the stimuli, especially to the conjunction of letter and typeface. The results suggest that frequency estimation of complex stimuli may be possible only for stimuli that have been processed as phenomenal objects.     

Context effects in visual word recognition: Lexical relatedness and syntactic context

In three experiments, we investigated how associative word-word priming effects in German depend on different types of syntactic context in which the related words are embedded. The associative relation always concerned a verb as prime and a noun as target. Prime word and target word were embedded in visually presented strings of words that formed either a correct sentence, a scrambled list of words, or a sentence in which the target noun and the preceding definite article disagreed in syntactic gender. In contrast to previous studies (O’Seaghdha, 1989; Simpson, Peterson, Casteel, & Burgess, 1989), associative priming effects were not only obtained in correct sentences but also in scrambled word lists. Associative priming, however, was not obtained when the definite article and the target noun disagreed in syntactic gender. The latter finding suggests that a rather local violation of syntactic coherence reduces or eliminates word-word priming effects. The results are discussed in the context of related work on the effect of gender dis-/agreement between a syntactic context and a target noun.     

Learning to Teach: The Acquisition and Maintenance of Teaching Skills

We reviewed 49 studies which used direct observation procedures to provide data on the effects of pre-service and inservice training in practical classroom teaching behaviors and skills. We found stronger effects for training packages which included classroom practice with performance feedback. The research provided conflicting evidence regarding the value of modeling, role-play, cueing systems, and contingency management components in practical skills training. The weakest training effects were those produced by microteaching, Minicourse, and protocol training packages. Twenty of the evaluations also provided follow-up data but the design of these studies did not permit any conclusions to be drawn regarding the training conditions which are necessary for the maintenance of newly acquired classroom teaching skills. We concluded that identification of the training conditions which are necessary for the maintenance of new teaching skills will require more thoughtful conceptualizations of maintenance and its measurement, and more carefully designed component analyses of those factors suggested by basic research as being necessary for maintenance.     

Two critical periods of protein and glycoprotein synthesis in memory consolidation for visual categorization learning in chicks

A protein synthesis inhibitor, anisomycin (ANI), and an inhibitor of glycoprotein synthesis, 2-deoxygalactose (2-D-gal), were used to investigate memory consolidation following visual categorization training in 2-day-old chicks. ANI (0.6 micromole/chick) and 2-D-gal (40 micromoles/chick) were injected intracerebrally at different time intervals from 1 hr before to 23 hr after the training. Retention was tested 24 hr post-training. Both ANI and 2-D-gal injections revealed two periods of memory sensitivity to pharmacological intervention. ANI impaired retention when injected from 5 min before to 30 min after the training or from 4 hr to 5 hr post-training, thus demonstrating that consolidation of long-term memory in this task requires two periods of protein synthesis. 2-D-Gal first produced an amnesia when it was injected in the interval from 5 min before to 5 min after the training. Injections made between 5 min and 5 hr post-training were without effect on the retention. The second period of memory impairment by 2-D-gal started at 5 hr post-training and lasted until 21 hr after the training. Administration of 2-D-gal made 23 hr after the training did not influence retention in the test at either 24 hr or 26 hr. These results are consistent with the hypothesis that two waves of protein and glycoprotein synthesis are necessary for the formation of long-term memory. The prolonged duration of performance impairment by 2-D-gal in the present task might reflect an extended memory consolidation period for a categorization form of learning.     

Unusual visual symptoms and Ganser-like state due to cerebral injury: a case study using (18)F-deoxyglucose positron emission tomography

Bizarre visual symptoms and absurd verbal responses to questions, in a 32-year-old man recovering from a severe asthma episode, suggested a possible conversion disorder with Ganser-like symptoms. Positron Emission Tomography (PET)revealed bilateral lesions involving occipital association cortex and posterior temporal and parietal lobes, most likely infarcts from hypoxia. PET permitted correlation of the patient's specific cortical lesions with his unusual perceptual, cognitive, and speech symptoms, including Ganser-like state, to a degree not previously possible in such cases.     

Staring and Compliance: A Field Experiment on Hitchhiking

A field experiment was conducted in which a single male, a single female, or a male-female couple attempted to hitch rides at four different traffic locations, under conditions in which the hitchhikers either stared at or looked away from oncoming drivers. It was found that staring increased the probability of a driver stopping from .03 to .067 (z = 2.96, p = .003). The female was a more successful hitchhiker than either the male or the couple, (z = 2.215, p = .026; z = 1.861, p .063, respectively).     

Judgments of differences and ratios of numerals

Each subject performed two tasks, dividing a line segment so that either (a) theratio of subjective lengths corresponded to the ratio of the magnitudes of two numerals or (b) thedifference in length was proportional to the numerical difference. Had subjects actually performed two operations on the same scale, the responses would have been nonmonotonically related. Instead, data for the two tasks were nearly identical and ordinally compatible with either a ratio or a subtractive model. The ratio model implied scale values for numerals that were a positively accelerated function of numerical value, inconsistent with previous results. With a nonlinear response function for graphic length, the subtractive model fit well, yielding scale values that were a negatively accelerated function of numerical value and a linear function of previously obtained scales. These results, together with other recent findings, suggest that subjects may perform the same operation in spite of instructions to judge “ratios” or “differences” and that this operation can be best represented by a subtractive model.