Equating the brightness of brief visual stimuli of unequal durations

The brightness of brief displays whose durations do not exceed a critical period of integration is known to covary with stimulus duration (Bloch’s law). There are cases in which the interdependence of duration and brightness introduces an unwanted confounding that must be avoided. Three methods for equating the brightness of brief stimuli displayed under computer control are described and evaluated, and an example of the outcome obtained with the most efficient procedure is reported.     

On the relationship between stimulus intensity and duration of visible persistence

Stimulus intensity and duration of visible persistence have been found to vary directly in some studies but inversely in others. Hawkins and Shulman (1979) have proposed that this inconsistency can be resolved by separating the studies that employed a decrement-threshold measure of persistence (Type I measure) from those that measured the total duration of persistence (Type II measure). They suggested that Type I measures yield an inverse relationship, whereas Type II measures yield a direct relationship between intensity and persistence. Hawkins and Shulman's model is incomplete in ways that are easily remedied. However, the model is totally contradicted by the experimental evidence. A new resolution of the inconsistent results is proposed in terms of retinal afterimages.     

学前和初小儿童智能筛查——图片词汇测试法

美国L.M.Dunn 1965年修改发表的皮勃迪图片词汇测试(PeabodyPicture Vocabulary Test简称PPVT)目前仍是美国智力不足协会(AAMD)所介绍的常用智能测试方法之一。本文参考PPVT制订出适合我国城市学前期与小学初期儿童的图片词汇测试;在上海市区进行标准化;制订了智龄量表、智商和百分位数量表。本测试再测信度r=0.945,二测试者间信度r=0.913。奇偶信度r=0.945,测试标准误σ=4.5。本方法与“学前儿童能力筛查五十项”,“画人试验”,“WPPSI”总智商、语言智商、操作智商,语文成绩,算术成绩的效度相关分别为:r=0.478,r=0.466,r=0.590,r=0.531,r=0.427,r=0.652,r=0.609。本测试制订以来已经数千人次应用,证明是一种简便易行,省时经济,准确性较好,且能进行集体测试的学前及小学初期儿童一般智能(generalintelligence)的筛查方法(Screening test)。     

Grading the ‘cultural literacy’ project

The essay examines the argument advanced by E.D. Hirsch, Jr., for instituting ‘cultural literacy’ as a fundamental priority of schools. A number of confusions and equivocations in Hirsch's reasoning are identified, and the propensity of his project to indoctrinate is exposed. Among the features of Hirsch's argument shown to be troubling are his shifting construal of ‘language’, his inconsistency about the requirements of cultural literacy, and his uncritical relation to traditional images of the American past and present. The upshot is to raise the question why Hirsch's project has elicited wide support and praise.     

On the relation between metacontrast masking and suppression of visible persistence

Does the introduction of additional contours in a display sequence (an operation known to reduce the strength of suppression in metacontrast) also reduce suppression of visible persistence? In three experiments, duration of visible persistence was estimated by a method in which successful performance depends on the temporal integration of a pattern whose elements are displayed in two successive frames. In this procedure, the arrival of the trailing frame is known to exert a suppressive influence on the visible persistence of the leading frame. Embedding the elements of the leading frame within additional contours (a line grid) reduced the degree of suppression exerted by the trailing frame. This did not occur when the grid was part of the trailing display. We conclude that suppression of visible persistence and metacontrast masking belong to the same class of events.