Graphics in written directions: Appreciated by readers but not writers

This series of studies investigated the ability of literate adults to exploit communications options that are available to writers but have no counterpart in speech. Specifically it examined people's use of sketches when giving written directions to help a stranger cross town. When writing an informal letter to a friend most directions were given in prose paragraph style (Experiment 1). Almost no-one included a sketch, even if given a street map as an aid. Yet most subjects could draw adequate sketch maps (Experiment 2), and everyone said yes when asked whether they would include a sketch in a letter. So the previous choices were not constrained either by graphic skill or by judgements concerning the appropriateness of a sketch, When people were asked to 'design' the back page of a leaflet they still did not include a sketch (Experiment 3). Experiment 4 showed that any bias in the instructions was towards rather than against the use of sketches. The need to generate the sketch was removed in Experiment 5 where subjects composed the leaflet page from pre-formed sections that included alternative routes in both words and diagrams. Nearly all subjects now included a sketch in their directions. In case subjects previously, in haste, had not considered the possibility of including a sketch map, they were made aware of the drawing option by rating the usability of route information in a variety of communication styles immediately before writing their own directions (Experiment 6). People rated directions that included diagrams as significantly more usable, but still most subjects did not include a sketch in the directions they gave. So the communication styles that readers recognized as successful were not determining their choices as writers. It is suggested that, when giving written directions, inexperienced writers rely too heavily on how they would respond as speakers.     

Contextual effects in difference judgments

Manipulating stimulus spacing, stimulus frequency, or stimulus range usually affects intensity judgments. In six experiments, I investigated the locus of analogues of these contextual effects in a “difference” estimation task. When all stimuli elicited the same taste quality, stimulus distribution affected the scale values only when water was included in the stimulus set (Experiments 1–3). When the subjective ranges of two taste qualities were manipulated, different scale values were obtained for the separate qualities in the two conditions (Experiment 4). Manipulation of the expected response distribution did not affect the scale values or the responses (Experiments 5–6). It is concluded that shifts in stimulus distributions or stimulus ranges result in shifts in subjective scale values. The contextual effects can be interpreted as relative shifts of a number of gustatory continua, with water lying on a separate continuum. Proposed is a model for context-dependent judgments, consisting of four stages: stimulus classification, stimulus placement, continuum placement, and continuum projection.     

Persistent crying and parenting: Search for a butterfly in a dynamic system

The risks and causes of persistent crying in early infancy are discussed on the basis of a study of 61 infants referred to the Munich Interdisciplinary Research and Intervention Program for Fussy Babies for persistent crying between 1 and 6 months of age, and of a community sample of 51 infants of the same age. Particular attention was paid to pre-verbal parent-infant communication, the development of which was interpreted in terms of a dynamic interactional system including both regulatory and communicative predispositions in infants and intuitive competence for supporting infant predispositions in parents. Neither a gut problem nor any other single causal factor was identified for persistent crying in the majority of cases. In contrast, persistent crying was significantly associated with multiple biological and psychosocial risk factors for both parents and infants. Neurological immaturity, difficult temperament and sleep problems in infants, and impaired psychological conditions, limited resources and failures of intuitive competences in mothers were found to threaten the developmental process in infants and give rise to ‘vicious circles’ which were destabilizing the interactional systems. Increased attention to intuitive parental competences is recommended as one effective model for therapeutic interventions.     

Carnap und der Physikalismus

Ohne Zusammenfassung     

De Finetti's earliest works on the foundations of probability

Bruno de Finetti's earliest works on the foundations of probability are reviewed. These include the notion of exchangeability and the theory of random processes with independent increments. The latter theory relates to de Finetti's ideas for a probabilistic science more generally. Different aspects of his work are united by his foundational programme for a theory of subjective probabilities.This work would not have been possible in its present form without the generous help of Prof. Maria Carla Galavotti. For several years, she has unfailingly answered all my requests for papers difficult of access, and discussed the details of interpretation as well as the philosophy of probability in general. To her I express my gratitude for everything.     

CULTURAL VARIATION IN PROBABILISTIC THINKING: ALTERNATIVE WAYS OF DEALING WITH UNCERTAINTY*

This study reviews research on cultural differences in “probabilistic thinking” and presents some intra- and inter-cultural findings. Strong differences are shown to exist between people raised under Asian and British cultures on measures of this ability. These differences were found to out-weigh any influence of subculture, religion, occupation, arts/science orientation and sex. Generally, Asians were found to adopt a less finely differentiated view of uncertainty both numerically and verbally than did the British sample. Numerical probabilities assessed by the Asians were more extreme and less realistic than those assessed by the British sample. Possible antecedents of these differences are outlined, and cultural differences in probabilistic thinking are shown to be compatible with decriptions of cultural differences in business decision making. It is argued that there are qualitative cultural differences in ways of dealing with uncertainty.     

Additivity and expected utility in risky multiattribute preferences

This experiment analyzed human preferences among even chance gambles for commodity bundles. The purpose of the experiment was to test several independence assumptions that distinguish between models for risky multiattribute preferences. In particular, the additivity and the expected utility part of the additive expected utility model were tested symmetrically. The degree and form of model violations were established, and the effects of instructions and of response modes were examined. All independence assumptions were violated by a bias to prefer a gamble or a commodity bundle that was previously matched against a standard. Systematic and strong violations that superseded this bias questioned the validity of the additive expected utility model. In violation of the additivity part of that model subjects consistently preferred the gamble with more balanced outcomes when comparing gambles with identical marginal probability distributions. This trend, called multiattribute risk aversion, was independent of subjects' single attribute risk attitude. Instructions and response modes had no noticeable impacts on these response patterns.     

Robust estimation of ability in the Rasch model

Estimating ability parameters in latent trait models in general, and in the Rasch model in particular is almost always hampered by noise in the data. This noise can be caused by guessing, inattention to easy questions, and other factors which are unrelated to ability. In this study several alternative formulations which attempt to deal with these problems without a reparameterization are tested through a Monte Carlo simulation. It was found that although no one of the tested schemes is uniformly superior to all others, a modified jackknife stood out as the best one in general, it was also super efficient (more efficient than the asymptotically optimal estimator) for tests with forty or fewer items. It is proposed that this sort of jackknifing scheme for estimating ability be considered for practical work.This research was funded through a grant from the Law Enforcement Assistance Administration (78-NI-AX-0047) to the Bureau of Social Science Research, Howard Wainer, Principal Investigator. We would like to thank Ronald Mead, Anne Morgan and James Ramsay for kind, generous, and invaluable help at various stages of the project.     

Choice reaction time with a random foreperiod

Choice reaction latencies were measured at three different a priori probabilities for two stimulus alternatives. Unlike the results of some other studies, the mean latency of a given response was nearly the same whether the response was correct or incorrect. The discriminable stimuli were a 1000- or a 1700-Hz tone presented at 70 dB SPL. Latencies and standard deviations, based on about 17,000 observations, are reported for three observers. The data are compared with predictions of the optimum sequential model of Wald and Stone and two modifications of that random-walk model, one proposed by Link and Heath and the other proposed by Laming. Fast-guess analyses were also carried out. The three-parameter version of either the sequential or the modified random-walk models provided reasonably accurate predictions of the mean data for each observer. The parameters estimated by the fast-guess analysis were unrealistic. There are three obvious differences between this experiment and most previous choice reaction-time experiments. First is stimulus modality#x2014;we used an auditory signal, whereas most of the previous studies used a visual signal. Second, the observers practiced more in this experiment than in most previous experiments. Finally, there was a random foreperiod with a heavy penalty for anticipations. One or more of these factors is the probable reason for the discrepancy between our results and those of previous studies.