Eye Movements and Lexical Access in Spoken-Language Comprehension: Evaluating a Linking Hypothesis between Fixations and Linguistic Processing

A growing number of researchers in the sentence processing community are using eye movements to address issues in spoken language comprehension. Experiments using this paradigm have shown that visually presented referential information, including properties of referents relevant to specific actions, influences even the earliest moments of syntactic processing. Methodological concerns about task-specific strategies and the linking hypothesis between eye movements and linguistic processing are identified and discussed. These concerns are addressed in a review of recent studies of spoken word recognition which introduce and evaluate a detailed linking hypothesis between eye movements and lexical access. The results provide evidence about the time course of lexical activation that resolves some important theoretical issues in spoken-word recognition. They also demonstrate that fixations are sensitive to properties of the normal language-processing system that cannot be attributed to task-specific strategies.     

Timing for the absence of a stimulus: the gap paradigm reversed

Contrary to data showing sensitivity to nontemporal properties of timed signals, current theories of interval timing assume that animals can use the presence or absence of a signal as equally valid cues as long as duration is the most predictive feature. Consequently, the authors examined rats' behavior when timing the absence of a visual or auditory stimulus in trace conditioning and in a "reversed" gap procedure. Memory for timing was tested by presenting the stimulus as a reversed gap into its timed absence. Results suggest that in trace conditioning (Experiment 1), rats time for the absence of a stimulus by using its offset as a time marker. As in the standard gap procedure, the insertion of a reversed gap was expected to "stop" rats' internal clock. In contrast, a reversed gap of 1-, 5-, or 15-s duration "reset" the timing process in both trace conditioning (Experiment 2) and the reversed gap procedure (Experiment 3). A direct comparison of the standard and reversed gap procedures (Experiment 4) supported these findings. Results suggest that attentional mechanisms involving the salience or content of the gap might contribute to the response rule adopted in a gap procedure.     

Behavioral complications of early pallidotomy

A review of stereotactic medial pallidotomy of the 1950s in five neurosurgical centers is presented. The surgical technique varied from one center to the other. The results of surgery, however, seemed to be quite equal, being positive in 70-90% of the patients. The surgical mortality ranged from 0 to 13%. Behavioral complications were adequately analyzed and reported from one center only and published by three independent neurologists. The side effects included drowsiness (12%), confusion (13.6%), mental deterioration (5%), memory deficit (13.6%), and dysphasia (7.5-24%, the rate depending on the concomitant brain atrophy). Among permanent side effects, 5% of the patients presented with a mild postoperative mental deterioration, whereas 13.6% had a severe memory deficit. In the four other centers, the results and side effects were analyzed only by the surgeons and were more biased. A comparison of the results and complications between Leksell's early medial pallidotomy of 1951-1957 and recent medial pallidotomies of the 1990s from two centers showed that 40 years ago Leksell had at least as good results as, and less serious complications than, two representative neurosurgeons of today. Even when positive clinical results of GPi pallidotomy have recently been reported from several centers, the patients seem to have improved relatively little, the dyskinesias excepted, and the rate of side effects has been quite high. The author is afraid that medial pallidotomy will soon be abandoned as a method of choice in the surgical treatment of Parkinson's disease, as in fact happened 40 years ago. One should look for better surgical alternatives and targets outside of the medial pallidum.     

Prenatal diagnosis, personal identity, and disability

A fascinating criticism of abortion occasioned by prenatal diagnosis of potentially disabling traits is that the complex test-and-abortion sends a morally disparaging message to people living with disabilities. I have argued that available versions of this "expressivist" argument are inadequate on two grounds. The most fundamental is that, considered as a practice, abortions prompted by prenatal testing are not semantically well-behaved enough to send any particular message; they do not function as signs in a rule-governed symbol system. Further, even granting, for the sake of argument, the expressive power of testing and aborting, it would not be possible, contra the argument's proponents, to distinguish between abortions undertaken because of beliefs about the disabling conditions the fetus might face as a child and abortions undertaken for many other possible reasons -- e.g., because of the poverty the fetus would face or the increase in family size that the birth of a new child would occasion. Here, I respond to criticisms of those arguments, and propose and defend another: the expressivist argument cannot, in general, distinguish successfully between abortion and therapy as modalities for responding to disabilities.     

Maze navigation by honeybees: learning path regularity

We investigated the ability of honeybees to learn mazes of four types: constant-turn mazes, in which the appropriate turn is always in the same direction in each decision chamber; zig-zag mazes, in which the appropriate turn is alternately left and right in successive decision chambers; irregular mazes, in which there is no readily apparent pattern to the turns; and variable irregular mazes, in which the bees were trained to learn several irregular mazes simultaneously. The bees were able to learn to navigate all four types of maze. Performance was best in the constant-turn mazes, somewhat poorer in the zig-zag mazes, poorer still in the irregular mazes, and poorest in the variable irregular mazes. These results demonstrate that bees do not navigate such mazes simply by memorizing the entire sequence of appropriate turns. Rather, performance in the various configurations depends on the existence of regularity in the structure of the maze and on the ease with which this regularity is recognized and learned.     

Varying intertrial interval reveals temporally defined memory deficits and enhancements in NTAN1-deficient mice

The N-end rule is one ubiquitin-proteolytic pathway that relates the in vivo half-life of a protein to the identity of its N-terminal residue. NTAN1 deamidates N-terminal asparagine to aspartate, which is conjugated to arginine by ATE1. An N-terminal arginine-bearing substrate protein is recognized, ubiquitylated by UBR1/E3α, and subsequently degraded by 26S proteasomes. Previous research showed that NTAN1-deficient mice exhibited impaired long-term memory in the Lashley III maze. Therefore, a series of studies, designed to assess the role of NTAN1 in short- and intermediate-term memory processes, was undertaken. Two hundred sixty mice (126 −/−; 134 +/ +) received Lashley III maze training with intertrial intervals ranging from 2–180 min. Results indicated that inactivation of NTAN1 amidase differentially affects short-, intermediate-, and long-term memory.     

The effects of averaging subjective probability estimates between and within judges

The average probability estimate of J > 1 judges is generally better than its components. Two studies test 3 predictions regarding averaging that follow from theorems based on a cognitive model of the judges and idealizations of the judgment situation. Prediction 1 is that the average of conditionally pairwise independent estimates will be highly diagnostic, and Prediction 2 is that the average of dependent estimates (differing only by independent error terms) may be well calibrated. Prediction 3 contrasts between- and within-subject averaging. Results demonstrate the predictions' robustness by showing the extent to which they hold as the information conditions depart from the ideal and as J increases. Practical consequences are that (a) substantial improvement can be obtained with as few as 2-6 judges and (b) the decision maker can estimate the nature of the expected improvement by considering the information conditions.     

Dyskinesias differentiate autistic disorder from catatonia

Autistic disorder and catatonia are neuropsychiatric syndromes defined by impairments in social interaction, communication, and restricted, stereotypical motor routines. Assessments of children with these disorders are typically restricted in scope by the patients' limited ability to comprehend directions. The authors performed systematic assessments of dyskinesias on six prepubertal boys with autistic disorder and mental retardation and on one adolescent male with catatonia to determine if this type of information could be routinely obtained. The boys with autistic disorder had more stereotypies and tics, a greater degree of akathisia and hyperactivity, and more compulsions than the adolescent with catatonia. Catatonia was associated with catalepsy and dystonic postures. The authors conclude that the diagnostic accuracy and specificity of neuropsychiatric syndromes may be enhanced by the systematic assessment of the dyskinesias associated with each condition.