Several varieties of perceptual independence are investigated. These include sampling independence, dimensional orthogonality, stimulus separability and integrality, and performance parity. A general multivariate perceptual theory is developed, and a precise definition of perceptual independence is offered. Each of these related concepts is then examined within the framework of this theory, and their theoretical interrelationships are explicated. It is shown that none of the concepts are equivalent to perceptual independence but that if separability holds, then sampling independence is equivalent to perceptual independence. Several simple tests of separability are suggested that can be applied to the same data as sampling independence. Dimensional orthogonality is shown to test for independence only if some strong distributional assumptions are made about the perceptual effects of stimuli. Reaction time and information-based performance parity criteria are examined. The potential for empirically testing each of these concepts is discussed.

Varieties of perceptual independence.

This article examines decision processes in the perception and categorization of stimuli constructed from one or more components. First, a general perceptual theory is used to formally characterize large classes of existing decision models according to the type of decision boundary they predict in a multidimensional perceptual space. A new experimental paradigm is developed that makes it possible to accurately estimate a subject's decision boundary in a categorization task. Three experiments using this paradigm are reported. Three conclusions stand out: (a) Subjects adopted deterministic decision rules, that is, for a given location in the perceptual space, most subjects always gave the same response; (b) subjects used decision rules that were nearly optimal; and (c) the only constraint on the type of decision bound that subjects used was the amount of cognitive capacity it required to implement. Subjects were not constrained to make independent decisions on each component or to attend to the distance to each prototype.

Decision rules in the perception and categorization of multidimensional stimuli.

Feature detection and letter identification.

A new theory of similarity, rooted in the detection and recognition literatures, is developed. The general recognition theory assumes that the perceptual effect of a stimulus is random but that on any single trial it can be represented as a point in a multidimensional space. Similarity is a function of the overlap of perceptual distributions. It is shown that the general recognition theory contains Euclidean distance models of similarity as a special case but that unlike them, it is not constrained by any distance axioms. Three experiments are reported that test the empirical validity of the theory. In these experiments the general recognition theory accounts for similarity data as well as the currently popular similarity theories do, and it accounts for identification data as well as the longstanding "champion" identification model does. The concept of similarity is of fundamental importance in psychology. Not only is there a vast literature concerned directly with the interpretation of subjective similarity judgments (e.g., as in multidimensional scaling) but the concept also plays a crucial but less direct role in the modeling of many psychophysical tasks. This is particularly true in the case of pattern and form recognition. It is frequently assumed that the greater the similarity between a pair of stimuli, the more likely one will be confused with the other in a recognition task (e.g., Luce, 1963; Shepard, 1964; Tversky & Gati, 1982). Yet despite the potentially close relationship between the two, there have been only a few attempts at developing theories that unify the similarity and recognition literatures. Most attempts to link the two have used a distance-based similarity measure to predict the confusions in recognition experiments (Appelman & Mayzner, 1982; Getty, Swets, & Swets, 1980; Getty, Swets, Swets, & Green, 1979; Nakatani, 1972; Nosofsky, 1984, 1985b, 1986; Shepard, 1957, 1958b). It is now widely suspected, however, that standard distance-based similarity measures do not provide an adequate account of perceived similarity (e.g., Krumhansl, 1978; Tversky, 1977). Our approach takes the opposite tack. We begin with a very powerful and general theory of recognition and use it to derive a new similarity measure, which successfully accounts for a wide variety of similarity results in both the recognition and the similarity literatures. The theory, which we call the general recognition theory, is rooted in the detection and recognition literatures and, in fact, is a multivariate generalization of signal-detection

Toward a Unified Theory of Similarity and Recognition

Self-reported measures of antiretroviral adherence vary greatly in recall time periods and response tasks. To determine which time frame is most accurate, we compared 3-, 7-day, and 1-month self-reports with data from medication event monitoring system (MEMS). To determine which response task is most accurate we compared three different 1-month self-report tasks (frequency, percent, and rating) to MEMS. We analyzed 643 study visits made by 156 participants. Over-reporting (self-report minus MEMS) was significantly less for the 1-month recall period (9%) than for the 3 (17%) or 7-day (14%) periods. Over-reporting was significantly less for the 1-month rating task (3%) than for the 1-month frequency and percent tasks (both 12%). We conclude that 1-month recall periods may be more accurate than 3- or 7-day periods, and that items that ask respondents to rate their adherence may be more accurate than those that ask about frequencies or percents.

https://www.ghdonline.org/uploads/OptimalRecallPeriodAdherenceWilson2007.pdf

Optimal Recall Period and Response Task for Self-Reported HIV Medication Adherence

Recent studies have begun to test certain fundamental assumptions underlying popular models of feature perception. This research is continued here. It was discovered that every basic assumption that was open to test in the present study was disconfirmed. However, several new characteristics of line and curve feature perception were discovered: (1) Feature perception sensitivity was inversely related to the number of features present in a stimulus pattern, and the decision criteria for reporting a feature decreased with the number of features contained in a pattern; (2) the decrements in sensitivity reported in (1) were greater for features lying inside a pattern than for those on the exterior; and (3) feature perception sensitivity actually improved if another feature was known to be correctly perceived during the same trial. Likewise, feature sensitivity decreased if another feature was missed on any trial. At the present time, a system that first extracts global and then local (more detailed) featural information provides a basis that qualitatively accounts for our findings and is also compatible with several other studies in the literature.

https://link.springer.com/content/pdf/10.3758/BF03206352.pdf

Modeling feature perception in brief displays with evidence for positive interdependencies

Among mathematical models of visual confusion of letters and similar material, those that posit a feature detection process have been especially popular. The present study provides direct tests of several of the central assumptions of such models with feature-stimuli composed of the blank, one of two straight line features, or both line features positioned at a right angle. In one condition, the two features were connected when they appeared together, whereas in the other condition they were separated by a gap. A model which makes the strong assumptions that the features are sampled (‘detected’) independently and then reported in a direct, unbiased fashion, performed acceptably in both conditions. Feature dependency models and those positing a biased decision process were ruled out on the basis of poor fits or lack of parsimony. The perceptibility (d′) of a specific feature depended on the stimulus that contained it in the Gap condition but not in the Connected condition. The relative perceptibility of the horizontal vs in the vertical features was also different in the Gap vs Connected conditions. The results were compared with other recent studies, including ones in which sampling independence was falsified, apparently because of greater stimulus complexity, and employing a stimulus set that did not contain all possible combinations of features.

Perceptual sampling of orthogonal straight line features

In our previous research on human perception of simple patterns (Townsend, Hu, & Evans, 1984), positive dependencies in the sampling of features were interpreted in terms of underlying sensory and decisional processes. Those findings suggested a model, called Blobloc here, which is further tested in the present study under various conditions of stimulus duration in Experiment 1 and feature-specific payoff ◊ stimulus duration in Experiment 2. Signal detection microanalyses generally supported Blobloc by discovering estimated d’ greater on a given feature when another feature was a "hit" or a "correct rejection." The bias, as estimated by ~, was less consistent in the microanalyses. The macroanalyses found that d’ and ~ on individual features behaved as predicted as functions of the experimental conditions. However, in contrast to previous results, the variation in number of features in a pattern was apparently too small to yield consistent d’ and ~ changes. In addition, increasing stimulus duration produced tendencies toward linear increases in/~ (significant in Experiment 2), a finding consistent with Blobloc. A plausible alternative medel (Correlated Noise model) is rejected by the results of the present and previous studies. Recent studies have begun to clarify how psychological and contextual variables influence the way we perceive simple patterns made up of elementary sets of lines and curves (e.g., Keren & Baggen, 1981; Loomis, 1982;

/pdf/feature-sensitivity-bias-and-interdependencies-as-a-function-2kca8nhsos.pdf

Feature sensitivity, bias, and interdependencies as a function of energy and payoffs

Well-specified feature detection models of visual character recognition typically assume feature sampling independence; that is, they assume that the detection of one feature is probabilistically independent of the detection of others. Recent results have suggested this assumption may be suspect with letter-like stimuli. The present study utilized very simple stimuli consisting of up to two straight-line segments that were either physically connected or separated by a gap. A strong model that assumed that features are reported if and only if they are sampled together with independence could not be rejected even when the lines were connected.

https://link.springer.com/content/pdf/10.3758%2FBF03334497.pdf

Gary G. Hu

Papers

Modeling feature perception in brief displays with evidence for positive interdependencies

Perceptual sampling of orthogonal straight line features

Feature sensitivity, bias, and interdependencies as a function of energy and payoffs

A test of visual feature sampling independence with orthogonal straight lines