Brunswik's lens model

Brunswik's lens model is a conceptual framework for describing and studying how people make judgments.

For example, a person judging the size of a distant object, physicians assessing the severity of disease, investors judging the quality of stocks, weather forecasters predicting tomorrow's weather and personnel officers rating job candidates all face similar tasks.

[1][2] A modern version used by Cooksey[3] incorporates into Brunswik's original model later developments from Hammond's Social Judgment Theory (Figure 1).

In the case of predicting college GPA, cues might include high school grades and test scores.

According to Hammond et al.,[2] p. 272:Knowledge of the environment is difficult to acquire because of causal ambiguity -- because of the probabilistic, entangled relations among environmental variables.

In the effort to do so, the organism brings a variety of processes (generally labeled cognitive), such as perception, learning, and thinking, to bear on the problem of reducing causal ambiguity.In research applications, individuals are typically asked to make judgments of many cases, typically 30 or more, each involving a different combination of values of the cues.

The resulting data are analyzed separately for each individual using a statistical model such as multiple regression analysis.

Ideally, a parallel analysis is applied to the criterion based on the same combinations of cue values judged by the person.

[8] Hammond[1] provides an excellent example of Brunswik's lens model applied to clinical psychologists' judgments about their patients (Figure 2).

In this study, 10 clinical psychologists judged IQ based on patient responses to four Rorschach test factors ("Cues" X1 ...X4).

Early in his career, Egon Brunswik was concerned with perceptual constancy, or how people maintain coherence in a changing environment.

Gestalt psychologists investigated a broad spectrum of perceptual illusions, eventually evolving into an examination of errors in perception.

J. Gibson rejected the fixation on studying illusions, emphasizing instead the importance of investigating behavior in natural environments, a perspective that identified them as ecological psychologists.

Brunswik's interest in understanding the relationship between an organism and its environmental structure can be traced back to his early collaboration with Edward C. Tolman in 1935.

This viewpoint contrasted with the prevailing trend among psychologists of that era, who were seeking principles of determinism as in the physical sciences, focusing on finding precise mathematical laws governing behavior.

Athanasou and Kaufmann (2015, Table 1)[10] describe the development of the probabilistic concepts during Brunswik's work that finally led to the lens model framework.

Since Brunswik developed the lens model to examine visual perception[19] it has been generalized to other kinds of judgments by Kenneth R. Hammond[2][20] and others.

As a result, some of Brunswik's original terms have fallen into disuse.The "Initial focal variable" refers to a property of the object that is to be judged or perceived, e.g., size, weight, or distance from the observer.

Quasi-rationality .- In line with the inherent probability character of object-cue and of means-end relationships, gross organismic coming-to-terms with the environment can thus never become foolproof, especially so far as the more vital remote distal variables are concerned.

Perceptual and behavioral functioning is spoiled much in the manner in which stray rays ... are apt to interfere with perfect focusing.

More essentially, however, they arise by virtue of the intrinsic undependability of the intra-environmental object-cue and means-end relationships that must be utilized by the organism .... (p. 23)The terms "stray causes: and "stray effects" were replaced with the "zones of ambiguity" by Hammond et al.[2] The lens model is a framework for understanding judgment and designing studies of judgment.

This was observed in the clinical inference case described above: "Certain clinicians were found to be using invalid cues, others neglected the valid ones"[1] (p. 261).

The left side of the lens model represents vicarious mediation—the structure of the task environment that allows various potentially substitutable ways of combining the cues to predict the criterion.

The right side of the lens represents vicarious functioning—the different ways that people combine the cues when making judgments.

Another basic tenet of Brunswik's theory is the importance of an idiographic approach – separate analyses of each person before aggregating the results.

This is not indirectly represented in the lens model because it is embedded in "Process detail" and "Stray effects" on the right side of Figure 3.