Naive Observer Research Articles

Clinical relevance of the ROC and free-response paradigms for comparing imaging system efficacies

Observer performance studies are widely used to assess medical imaging systems. Unlike technical/engineering measurements observer performance include the entire imaging chain and the radiologist. However, the widely used receiver operating characteristic (ROC) method ignores lesion localisation information. The free-response ROC (FROC) method uses the location information to appropriately reward or penalise correct or incorrect localisations, respectively. This paper describes a method for improving the clinical relevance of FROC studies. The method consists of assigning appropriate risk values to the different lesions that may be present on a single image. A high-risk lesion is one that is critical to detect and act upon, and is assigned a higher risk value than a low-risk lesion, one that is relatively innocuous. Instead of simply counting the number of lesions that are detected, as is done in conventional FROC analysis, a risk-weighted count is used. This has the advantage of rewarding detections of high-risk lesions commensurately more than detections of lower risk lesions. Simulations were used to demonstrate that the new method, termed case-based analysis, results in a higher figure of merit for an expert who detects more high-risk lesions than a naive observer who detects more low-risk lesions, even though both detect the same total number of lesions. Conventional free-response analysis is unable to distinguish between the two types of observers. This paper also comments on the issue of clinical relevance of ROC analysis vs. FROC for tasks that involve lesion localisation.

The social life of corvids

The social life of corvids

Fixational Eye Movements Are Not an Index of Covert Attention

The debate about the nature of fixational eye movements has revived recently with the claim that microsaccades reflect the direction of attentional shifts. A number of studies have shown an association between the direction of attentional cues and the direction of microsaccades. We sought to determine whether microsaccades in attentional tasks are causally related to behavior. Is reaction time (RT) faster when microsaccades point toward the target than when they point in the opposite direction? We used a dual-Purkinje-image eyetracker to measure gaze position while 3 observers (2 of the authors, 1 naive observer) performed an attentional cuing task under three different response conditions: saccadic localization, manual localization, and manual detection. Critical trials were those on which microsaccades moved away from the cue. On these trials, RTs were slower when microsaccades were oriented toward the target than when they were oriented away from the target. We obtained similar results for direction of drift. Cues, not fixational eye movements, predicted behavior.

Unmuddling the Debate on Human Diversity

Unmuddling the Debate on Human Diversity Race (The Reality of Human Differences) Vincent Sarich and Frank Miete Westview Press, Boulder (Co) 2004 A Silly Debate The thesis of this book is simple enough: Differences between human races are real; they are of substantial magnitude; and they are, sometimes at least, important. The naive observer will object that there is little originality in this thesis. After all, every hairdresser knows that there are important race differences. At least, every hairdresser in the Caribbean knows it. The ostensible reason for this book's existence is that some intellectuals don't seem to know it. During the past half-century, articles claiming that race differences are minimal, unimportant, or non-existent have proliferated both in the popular press and in academic journals-including even The Mankind Quarterly (Biondi and Rickards, 2002). Sarich's and Miele's logic is not too different from the hairdresser's, although their book is written for intellectuals rather than hairdressers. The authors are well placed to write about this subject. Vincent Sarich has been one of the leading figures in population genetics for the past 30 years, and his work on the molecular clock arid its application to human evolution has been a major contribution to our current understanding of modern human origins. Frank Miele is editor of Skeptic magazine, where the debunking of pseudoscience and popular superstition is part of his job description. The academic debate about the non-existence of race is a rhetorical controversy rather than a substantive one, revolving around the definition of the term race. The impetus behind the claim that race does not exist is not scientific but normative, modeled on the newspeak in Orwell's 1984: the belief that people's thoughts are determined by the categories made available by their language. If we remove the term race from our vocabulary, racism will end because people can no longer think about race differences and their implications. Never mind that the Sapir-Whorf hypothesis of linguistic determinism has not fared too well in the scientific arena (Pinker, 1994). This fruitless academic debate with its surrealistic touch and Orwellian undertones is unsuitable for any book aimed at a wider audience. But fortunately, Sarich and Miele are not interested in rhetoric but in the real thing: not what is in our heads, but what is in the world. The authors start by showing that the reality of race differences is sell-evident to the layman and is taken for granted by the legal system. Common people can tell a Japanese from a Kenyan on first sight. Only some intellectuals can't. But molecular biologists can. True, the majority of genetic diversity among humans is within rather than between races, but some genetic markers do vary substantially among races. Sarich describes how a person's race can be determined from his DNA. In the latest version of the DNAPrint method, used in forensics, information from 73 DNA polymorphisms is combined to determine not only a person's race, but even the degree of admixture with great accuracy. If you happen to be 85% African and 15% Native American, the DNA test will show it! Nor is the awareness of race differences limited to modern societies. Miele shows that the early Egyptian, Greek, Indian, Chinese and Arab civilizations all distinguished races not only by their physical appearance, but also attributed behavioral characteristics to them. Race prejudice is not a modern invention but can be traced through the ages! The authors proceed by tracing the modern history of ideas about race differences, starting with the pre-Darwinian opposition between monogenists and polygenists: those who believed that people were created by God only once and developed into separate races only recently, and those who believed that the races were created separately. And on it goes through the post-Darwinian controversies that finally led to the widespread denial of race differences in the late 20lh century: between Ernst Haeckel and Rudolf Virchow, Franz Boas and Madison Grant, and between Carleton Coon and Ashley Montagu. …

Children’s ability to attribute different interpretations of ambiguous drawings to a naive vs. a biased observer

In two experiments we investigated 5- to 7-year-olds’ ability to attribute to a naive or a biased observer an interpretation of ambiguous drawings (restricted views of a nondescript part of a depicted object) corresponding to that observer’s mental state: ignorance for the naive observer and expectation for the biased observer. In Experiment 1, in which the expectation was only based on the observer’s prior viewing experience, children mostly failed to infer a proper interpretation for both a biased and a naive observer; instead, they ascribed to this character an interpretation corresponding to the real identity of the target picture. In Experiment 2, in which the expectation was additionally based on a more stable characteristic of the observer, a high percentage of children succeeded in generating for the biased observer an interpretation according to that expectation. For the naive observer, children’s answers seemed to be at random. In addition, we used a replication of Gopnik and Astington’s “book” task (1988), obtaining different results. We conclude that children aged 5 to 7 years have a rudimentary understanding of the interpretive nature of external representations. Hence their varying performance on interpretive theory of mind tasks, depending on the details of the task or the context in which it is presented.

Social influences on the amount of food eaten by Norway rats

A naive observer Norway rat offered a choice between two foods, after it interacts with a demonstrator rat fed one of those foods, increases its preference for whichever food the demonstrator rat ate. It is not known whether interaction with a demonstrator rat would also increase the amount that an observer rat would eat if it were given access only to the food the demonstrator had eaten. In this study, each observer rat interacted with a demonstrator rat fed a food, either familiar or unfamiliar to the observer, and the observer was then offered a weighed sample of the food that the demonstrator had eaten. It was found that, during the first hour of testing, observer rats that had interacted with demonstrators fed an unfamiliar food, increased their intake of that food roughly four-fold. Observer rats that interacted with demonstrator rats fed a familiar food however, did not increase their food intake. Socially enhanced intake of unfamiliar food was seen only during the first hour that observers had access to food and was compensated for during the next 23h of feeding. This short-term increase in observer intake of unfamiliar foods appeared to result from socially-induced motivation to ingest unfamiliar foods rather than from socially-induced reduction in neophobia.

Some musings on systematic variability and speech recognition

One of the major problems in speech recognition is the inability of trained models to generalize appropriately to channel variations, new speakers, or modified acoustics. The naive observer would believe that a multimillion-parameter system should be sufficient! The difficulty appears to be too many parameters rather than too few. For moderate-sized training corpora, systems learn all of the conditions in the training data rather than generalizing from the exemplars. (For instance, speech recognition algorithms will generally score the speech from a training speaker higher than that from a speaker who was excluded from the set.) One can force the issue by explicitly modeling systematic variation, and then ‘‘normalizing’’ at the front end or in the acoustic model. Two exemplars of this philosophy are Cepstral mean subtraction and vocal tract normalization [Frontiers in Speech Processing 94, LDC96s40, Linguistic Data Consortium (1995)]. In each case a single parameter from a very restrictive model is estimated, and accounting for the variability explicitly improves performance. Concrete examples of these situations are offered, and the impact of this work on future work in automatic speech recognition is discussed.

Social influence on avoidance of dangerous stimuli by rats

Three experiments were conducted to determine whether a naive observer rat would avoid contact with a shock prod after watching a demonstrator rat contact, be shocked by, and defensively bury the prod. We found that observer rats took longer to contact prods that had delivered a shock to and been buried by a demonstrator rat than to contact prods that had not delivered shock and had not been buried. However, observer rats contacted prods buried by an unseen demonstrator rat or by an unseen experimenter with the same latencies as those for prods they had seen deliver shock to and be buried by a demonstrator rat. In large enclosures, subjects took 1–2 h longer to contact buried prods than to contact unburied prods. We conclude that alteration of the physical environment by individuals receiving noxious stimulation can significantly reduce the probability that conspecifics will contact the noxious stimulus. Observational learning per se, however, need not be involved.

Pain scores in infants: a modified infant pain scale versus visual analogue

This study describes an observational system (modified infant pain scale, MIPS) with elements from a previously published observational scale and from assessments of video-recorded infant facial expressions. It was designed to allow rapid and repeated assessments of pain in infants after brief training by an observer without pediatric experience. Forty healthy term infants (17 ± 7 weeks) undergoing elective surgery had simultaneous independent assessment of pain using two scales: a naive observer used the MIPS and an experienced pediatric nurse used a 10-cm unmarked horizontal visual analogue scale (VAS). This validation of the MIPS included its division during analysis into partial (P-MIPS, without data on sleep or vital signs) and total scores. Infants had a broad range of MIPS scores, and the two scales categorized infants as “comfortable” or “not comfortable” with a high degree of concordance. The MIPS was easily incorporated into an infant's physical examination. We recommend its use for two-point clinical pain assessment.

Breaking Barriers: The Relation between Contract and Intellectual Property Law

This Article examines the -symbiotic relationship between copyright and contract law. The intellectual property bargain, or the delicate balance that allegedly exists in current intellectual property law, cannot be seen merely as a matter of a balance stated in property law rules. An interaction between intellectual property and contract has always been a primary characteristic of intellectual property distributed in the open market and that interaction is central to whatever balance has been achieved. When one speaks about an existing balance in the property rights sector, it is futile to focus solely on the statutory provisions of the copyright, patent or trademark laws. One must, of necessity, understand and incorporate the fact that the policy choice has always assumed that property rights are routinely transferred, waived, released, and licensed. Only the most naive observer, or one with a clear political agenda, can look at the intellectual property laws and their history and suggest that policy in the property sphere trumps or precludes the influence of contract. In contractual relationships, underlying property rights are often relatively unimportant. They provide rules that state a legal position that exists between the contracting parties unless the parties otherwise agree. Contract law provides other default rules. In the digital world, the contract rather than the underlying property law defines the product. This being said, however, there are some settings in which contract law, intellectual property, or competition law place limits on the ability to enforce some contract terms. This Article explores some of these areas and describes their limited role in modem commerce.

On representation, goals and cognition

Abstract In this paper we address three concepts that are much talked about in the animal robotics community. These concepts are (1) representations, (2) goals, and (3) minimal cognition. We want to distinguish between information as an objective commodity and representation as something which involves a user, i.e. a system which accesses and uses information. Information per se lies out there and exists independently of any system that makes use of it. Representations presuppose design and require a user. We want to distinguish different kinds of purposive behaviour, which involve different notions of goals, which themselves appear to be different from the point of view of the agent, the designer and the naive observer. We want to try to define cognition in terms of the minimal criteria that would be acceptable in view of our definitions of representations and goals. We recognise that full‐blown cognition may require ingredients other than those of minimal cognition.

Effects of access to food during training on social learning by Burmese red junglefowl

Bunnese red junglefowl, Gal/us gallus spadecius, prefer to feed at sites similar to those where they have previously observed conspecifics foraging successfully (McQuoid & Galef 1992). Both naive fowl exposed to colour video images of conspecific tutors feeding from visually distinctive feeding sites and naive fowl that directly observed conspecific tutors eating at such sites preferred to eat at locations similar to those where they had seen tutors eating (McQuoid & Galef 1992, 1993). Such laboratory demonstrations of the ability of junglefowl to treat conspecifics as sources of infonnation about where to feed suggest that, in natural circumstances, birds that forage in flocks will use the behaviour of fellow flock members to increase the efficiency with which they discover profitable foraging sites. On the other hand, results of a series of studies of observational learning by pigeons, Columbia livia (Giraldeau & Lefebvre 1987) suggest that social learning about feeding behaviour may be inhibited if observing birds are allowed to feed while watching conspecific tutors feed. If eating by observers does, in fact, interfere with their learning by watching when, where or how others feed, then it might not be appropriate to extrapolate from McQuoid & GalePs (1992, 1993) laboratory situations (where observer fowl were not permitted to feed while watching their tutors feed) to more natural situations (where members of a flock might be expected to feed as they observe their fellows foraging). The present experiment was undertaken to determine whether allowing naive observer fowl to eat while they watched life-size colour video images of trained tutors feeding from visually distinctive foraging sites would interfere with observers acquiring a preference for the type of feeding site where they had seen conspecifics forage successfully. To begin an experimental session, we placed a pair of 2J -28-day-oJd jungJefowJ, born and reared

Dissecting Surgery: Forms of Life Depersonalized

When surgeons drape human bodies in green or blue cloths, when they erect a barrier between their eyes and the patient's face, when they narrow their gaze to that small portion of the body into which the scalpel is to penetrate, when they surround their activities with antiseptic walls, what are they doing? Are they `objectifying' and `depersonalizing' the body? How might one tell? What method might one use to find out? What might such a claim mean? This paper explores these methodological and philosophical issues, comparing surgery and other assaults on the body in a variety of contexts. The conclusion is that existing treatments of the problem fail to understand the surgeon's world as routine. Much of the drama and ritual that analysts read into the operating theatre results from transference of the naive observer's viewpoint to the world of the surgeon.

Social transmission of information about multiflavored foods

We fed demonstrator rats diets made by adding three, four, or five different flavorants to powdered Purina Rat Chow. We then allowed each of these demonstrator rats to interact with a naive observer rat for 30 min. We found that (1) observers exhibited enhanced preferences for many of the individual flavorants in the multiflavored diets that their respective demonstrators had eaten and (2) the probability of an observer exhibiting enhanced preference for an individual flavorant in its demonstrator’s diet decreased as the number of flavorants in that diet increased. In Experiment 2, the individual members of pairs of subjects were each fed one of two different four-flavored diets. The subjects in each pair interacted for 30 min, then each chose between two single-flavored diets. One of these single-flavored diets contained a flavorant in the four-flavored food that a subject had itself eaten; the other single-flavored diet contained a flavorant in the four-flavored diet that a subject’s partner had eaten. The subjects showed enhanced preferences for six of eight flavorants in the four-flavored diets that their respective partners had eaten.

A Context-based Introduction to Aircraft Radio Communications

To the naive observer, aircraft radio communications can be as incomprehensible as a foreign language. As with any language, understanding what is said requires not only a knowledge of specific terms, but also a familiarity with the context in which the communication occurs. The novice, whether a beginning pilot or a researcher involved in aviation-related investigations, is too often expected simply to pick up such knowledge on the job. We have developed a set of computer-based training materials that provides the user with the necessary conceptual framework as well as the specific vocabulary used in basic flight contexts. The design, content, use by students, and plans for future development are discussed.

First Snow

of this earth." The father seems as rootless as Walking John Gay, whose words bring back to mind the river of earth metaphor: "They's a world of dirt flowed under my feet. I never crawled when I was a baby. Just riz up and walked at ten months. I'm a-mind to see every living hill against I die." It is the father, and thus others in his train, who float on the surface of this river, knowing least the answer to Brother Sim Mobberly's question: Oh, my children, where air we going on this mighty river of earth, a-borning, begetting, and a-dying-the living and the dead riding the waters? Where air it sweeping us? Perhaps a little child, a nameless seven-year-old boy, shall lead them. Or perhaps a poet. It is likely they are the same. Surely the narrator of the poem, "River of Earth," is the child of vision, the naive observer, the innocent seer of the novel. The boy has a yearning for poetry, "music not set to notes." When asked what he would do with a bagful of money, he says, "I'd buy me a broadside off the peddle-woman.' Here again in the novel we find the frustrated visionary , the one who knows, modestly, "least or all," what he will never understand. And so he turns to poetry. Poet and child are one. They are James Still. This is today's book, and tomorrow's. Silver Hills The first snowfall silvers the hills on upper reaches and turns each simple tree into delicate filigree. The hilltop becomes a frosted decoration each pine a Christmas tree. The autumn gold transmutes to winter silver. -David F. Moore First Snow Walnut and amber wrap me, rocking, relaxed in the scent of yeast bread, rising. Through the cold gleam of glass I watch black stripped tree arms cradle snow, iced, in winter silence. -Margaret D. Kirkland ...

Social learning and social transmission of foraging information in Norway rats (Rattus norvegicus)

Adult male Norway rats were tested in a first experiment to see whether foraging efficiency could be improved by social learning. Observers were placed in one of four conditions in which they were paired with demonstrators that either had or had not been previously trained to dig for buried carrot pieces, and in which the demonstrators either did or did not have carrot buried in the experimental enclosure. Observers in the group with trained demonstrators that did have carrot pieces buried in the experimental area during the observation period subsequently unearthed more buried carrot, did so more rapidly, and were generally more active than were the observers in the other three groups. In a second experiment, chains of transmission were established by allowing each observer to act as a demonstrator for the next naive observer. Enhanced levels of digging behavior were maintained across eight transmission episodes in three transmission groups relative to a no-transmission control group, the performance levels becoming stable after five transmission episodes at a level significantly above that of the control group. The study demonstrates that social learning and transmission mechanisms exist which might result in the diffusion of certain patterns of behavior through populations of Norway rats.

Further evidence that Norway rats do not socially transmit learned aversions to toxic baits

Three experiments were undertaken to examine the effects of interactions with demonstrator rats made ill by injection of lithium chloride (LiCl) on the later food choices of their observers. We found that (1) observer rats that had been taught an aversion to an unfamiliar diet exhibited a substantial reduction of that aversion after interacting with poisoned demonstrators that had eaten the diet to which the observers had learned an aversion, (2) exposure of an observer rat to poisoned demonstrator rats that had eaten a diet interfered with later acquisition by the observer of an aversion to the diet that the poisoned demonstrators had eaten, and (3) after interacting with poisoned demonstrators that had eaten one of two diets, observers that ate both diets and were then made ill formed an aversion to whichever diet their respective, poisoned demonstrators had not eaten. The present experiments, like previous studies both in our laboratory and elsewhere, failed to provide any evidence that naive observer rats will learn to avoid a food as a result of interacting with demonstrator rats that had eaten the food and exhibit symptoms of toxicosis. To the contrary, observer rats in the present experiments exhibited an enhanced preference for foods eaten by sick demonstrators.

Public and private self-consciousness and social phobia.

The relationship between public and private self-consciousness and self-report questionnaires, clinician ratings, and various measures derived from an individualized simulation of an anxiety-provoking situation was examined in a sample of men and women seeking treatment for social phobia. As predicted, public, not private, self-consciousness was generally related to self-report and naive observer ratings of anxiety and to behavioral disruption during the simulation. The predicted relationship between public self-consciousness and how accurately subjects evaluated their performance in the anxiety-provoking situation was marginally supported. Hypotheses regarding the relationship between private self-consciousness and self-reported anxiety during an anxiety-provoking situation, and between private self-consciousness and the correspondence between physiological assessment and self-report, were not supported. The discussion focuses on methodological issues and the theoretical implications of the relationship between self-consciousness and social anxiety.

Conceptual Perspective Taking: Children's Ability to Distinguish What They Know from What They See

One part of understanding the difference between external reality and mental life involves the ability to differentiate what is seen from what is known. This research investigated the development of children's ability to make the seeing-knowing distinction in the context of conceptual perspective taking. In Experiment 1, 2 developmental levels were found to account for children's performance when asked about a naive observer's knowledge of the identity of objects. At Level 1 (from about 4-6 years of age), children tend to behave as if seeing part of an object is sufficient for someone to share the children's knowledge of the object's identity. Even at 4 years of age, however, children often realize that a small, nondescript part of an object does not provide sufficient information for an observer to know the object's present actions (e.g., that a rabbit is jumping) or nonperceptual information about the object (e.g., that the rabbit has a brother). At Level 2 (after about 6 years of age), children appreciate that someone who shares their visual perspective may not be able to identify the object in view. In Experiment 2, 4- and 6-year-old children were given training designed to make them aware that there may be many interpretations for the same information. 4-year-old children in the training condition performed significantly better on subsequent perspective-taking tasks.