Eye movements during the reading of compound words and the influence of lexeme meaning

We examined the use of lexeme meaning during the processing of spatially unified bilexemic compound words by manipulating both the location and the word frequency of the lexeme that primarily defined the meaning of a compound (i.e., the dominant lexeme). The semantically dominant and nondominant lexemes occupied either the beginning or the ending compound word location, and the beginning and ending lexemes could be either high- or low-frequency words. Three tasks were used--lexical decision, naming, and sentence reading--all of which focused on the effects of lexeme frequency as a function of lexeme dominance. The results revealed a larger word frequency effect for the dominant lexeme in all three tasks. Eye movements during sentence reading further revealed larger word frequency effects for the dominant lexeme via several oculomotor motor measures, including the duration of the first fixation on a compound word. These findings favor theoretical conceptions in which the use of lexeme meaning is an integral part of the compound recognition process.     

Phonology in multisyllabic word recognition

The present study used two word-naming experiments to investigate whether a phonological representation is computed in the perception of multisyllabic words. In the first experiment, 100- or 250-msec beginning syllable previews were given, followed by the whole word. The results indicated that no phonological representation was computed at 100 msec, but a phonological representation was computed at 250 msec. In Experiment 2, the second syllable was given as a prime for either 100 or 250 msec. The results showed that no phonological representation was computed for the end of a multisyllabic word. Results are discussed in terms of current dual-route theory and connectionist models.This research was supported by a National Science Foundation grant BNS90110067. We thank Kim Clements, Cindy Connine, Fred Smith, Steve Straight, Sheldon Li, Steve Specht, Greg Boheimer, Deb Briihl, Rich Topoloski, Anna Chomiak and Chris Bruun for their support.     

Breast cancer and cerebral laterality

In reviewing and summarizing work at our institution, we have identified some surprising consistencies in patients with breast cancer. Breast cancer shows four features of cerebral laterality: excess left-handedness, atypical season-of-birth patterns, the risk factor of advanced maternal age, and an association with prenatal sex hormones. Since hypopigmentation also relates to cerebral laterality, a consequence of the association of breast cancer and cerebral laterality is that eye color should be measured as a function of side of disease and age at diagnosis in women with breast cancer.     

Effects of centrality on retrieval of text-based concepts

Four experiments examined the effect of centrality on retrieval time using a wide range of testing conditions. Subjects read passages containing concepts that were rated as central, moderately central, or peripheral to a passage, and then were asked to retrieve those concepts. Experiment 1 used a probe recognition task that contained foils that were unrelated to the passage, and it was found that central concepts were recognized more quickly than peripheral concepts. In Experiment 2, the foils were passage related, resulting in a much larger recognition advantage of central concepts over peripheral concepts. Experiment 3 used a speeded-recall task. Again central concepts were recalled more quickly than less central concepts. Experiment 4 ruled out a simple strength argument. The results of all four experiments are discussed in terms of text being represented as an integrated network. Within this network, central concepts are more interconnected, providing additional access routes that facilitate retrieval.     

Input-specific long-term potentiation in the rat lateral amygdala of horizontal slices

Long-term potentiation (LTP) at input synapses to the lateral nucleus of the amygdala (LA) is a candidate mechanism for memory storage during fear learning. Cellular mechanisms of LTP have been nearly exclusively investigated in coronal brain slices. In our experiments, we used a horizontal brain slice preparation of rats that preserved most of the connections to cortical areas and the hippocampus. The stimulation electrodes were located either within the external capsule (EC) or the LA. The aim of the present study was to investigate the mechanisms of LTP induced either by weak theta burst stimulation (TBS) or strong high frequency stimulation (HFS) using the two different stimulation sites. Whereas both TBS and HFS of afferences running through the LA induced stable LTP, TBS failed to induce LTP of EC-inputs to the LA. The present findings also show that LTP in the LA exhibits vulnerability at different time windows after induction. The time window was dependent on the kind of stimulated afferences. Later LTP becomes resistant to disruption by low frequency stimulation. We could show that both used inputs depended on NMDA receptors for LTP-induction. LTP induced by stimulation of fibers within the LA was not altered by nifedipine (10 microM). In contrast, EC-induced LTP was dependent on L-type voltage-gated calcium channels (VGCC). Finally, we found a higher magnitude of LTP in females using TBS, whereas HFS did not cause gender-specific differences. Our study supports the conclusion that the form of LA-LTP depend on which afferences are activated and what pattern of stimulation is used to induce LTP.     

The impact of letter detection on eye movement patterns during reading: Reconsidering lexical analysis in connected text as a function of task

A comparison was made between reading tasks performed with and without the additional requirement of detecting target letters. At issue was whether eye movement measures are affected by the additional requirement of detection. Global comparisons showed robust effects of task type with longer fixations and fewer word skippings when letter detection was required. Detailed analyses of target words, however, further showed that reading with and without letter detection yielded virtually identical effects of word class and text predictability for word-skipping rate and similar effects for different word viewing duration measures. The overall oculomotor pattern suggested that detection does not substantially shift normal reading movements in response to lexical cues and thereby indicated that detection tasks are informative about word and specifically word class processing in normal reading.     

Memory for word location during reading: Eye movements to previously read words are spatially selective but not precise

In two experiments, readers' use of spatial memory was examined by asking them to determine whether an individually shown probe word had appeared in a previously read sentence (Experiment 1) or had occupied a right or left sentence location (Experiment 2). Under these conditions, eye movements during the classification task were generally directed toward the right, irrespective of the location of the relevant target in the previously read sentence. In two additional experiments, readers' knowledge of prior sentence content was examined either without (Experiment 3) or with (Experiment 4) an explicit instruction to move the eyes to a target word in that sentence. Although regressions into the prior sentence were generally directed toward the target, they rarely reached it. In the absence of accurate spatial memories, readers reached previously read target words in two distinct steps--one that moved the eyes in the general vicinity of the target, and one that homed in on it.     

Loss of vision during the retinal stabilization of letters

Upper- and lower-case letters of the alphabet were stabilized until loss of vision occurred. Loss of straight-line visibility was the most frequently reported perceptual event. Occasionally, features of letters separated spatially before their loss of visibility. In both instances, loss of visibility often resulted in the perception of a less complex letter. Confidence ratings for each loss of letter visibility indicated that participants were quite certain about perceived fragmentations. In a control experiment, participants were asked to guess how letters would fragment during stabilization. Again, loss of line visibility was the most frequently reported event. However, spatial separation of features was rarely predicted and complex letters were not predicted to fragment into simpler letter forms. Furthermore, the confidence in predicted fragmentation was quite low. These results are consistent with the view that losses of visibility during retinal stabilization constitute a distinct perceptual experience. Fragmentations appear to be determined by the availability of less complex letter forms and by the loss of subletter information, consisting of letter features and information specifying spatial configurations.     

Educational and career aspirations of secondary school students in Grenada following the American intervention

This paper reports a study of educational and occupational aspirations of secondary school students in Grenada following the 1983 American intervention. Questionnaire data were obtained from 729 students attending 7 of the island's 18 secondary schools. A status attainment model containing parental and family characteristics was tested. It was discovered that Grenadian students have exceptionally and unrealistically high aspirations. Although the opportunity structure in Grenada is very limited compared to that in the United States, the island's students have higher levels of aspirations. The status attainment model was not very useful in explaining either educational or occupational aspirations, as the levels of explained variance were less than 5%. The implications of high aspirations and low opportunities for the future of Grenada are discussed.     

Higher frequency of left-breast cancer: a possible explanation

A study of 1027 women with unilateral breast cancer showed that ipsilateral breast cancer was more common before age 45 and contralateral thereafter. The data suggest a possible explanation of the higher incidence of left-breast cancer in American women. A higher percentage of left-handed women developed breast cancer before age 45, but the over-all incidence of unilateral breast cancer was not greater in left-handed women than in right-handed or ambihanded subjects.