Dale J. Cohen

Numerical bias in bounded and unbounded number line tasks

The number line task is often used to assess children’s and adults’ underlying representations of integers. Traditional bounded number line tasks, however, have limitations that can lead to misinterpretation. Here we present a new task, an unbounded number line task, that overcomes these limitations. In Experiment 1, we show that adults use a biased proportion estimation strategy to complete the traditional bounded number line task. In Experiment 2, we show that adults use a dead-reckoning integer estimation strategy in our unbounded number line task. Participants revealed a positively accelerating numerical bias in both tasks, but showed scalar variance only in the unbounded number line task. We conclude that the unbounded number line task is a more pure measure of integer representation than the bounded number line task, and using these results, we present a preliminary description of adults’ underlying representation of integers.

Why can't most people draw what they see ?

The study presented a theoretical and empirical approach to the adult drawing process. Four possible sources of drawing inaconacies were described: mispercepfion of the object, inability to make good representational decisions, deficient motor skills, and misperception of the drawing. In four studies the degree to which the latter three sources conlributed to drawing inaccuracies was assessed. The results suggest that (a) motor coordination is a very minimal source of drawing inaccuracies, (b) the artists decision-making process is a relatively minor source of drawing inaccuracies, and (c) the artists mispereeption of his or her work is not a source of drawing inaccuracies. These results suggest that the artists misperception of the object is the major source of drawing errors. Although childrens drawing abilities have been studied extensively (e.g., Broderick & Laszlo, 1989; Freeman, 1980, 1987; Lee, 1989; Reith, 1988; Wolf & Perry, 1988), those of adults have been relatively ignored in the scientific literature. There have been extensive accounts of the adult drawing process in the art history literature (e.g,, Anaheim, 1986; Gombrich, 1984; Richter, 1970; Rosenberg, 1963; Sze, 1956). These accounts are important because they provide working theories, but they lack empirical support. This article presents a theoretical and empirical approach to the adult drawing process; our discussion is strictly limited to the visual accuracy of drawings of a photograph) Our use of the term visual accuracy suggests that an objective description of accuracy can be made. This description, however, is both culturally determined and difficult to describe (see Gombrich, 1984). We operationally defined a visually accurate representation as one that can be recognized as a particular object at a particular time and in a particular space, rendered with little addition of visual detail that cannot be seen in the object represented or with little deletion of visual detail. According to this definition, a photograph is an excellent example of a visually accurate, two-dimensional representation because it adds and deletes very few visual details. Picassos Guernica, however, although a great work of art, would probably rank low as an example of a visually accurate representation. Because this definition relies on a viewers judgment, however, the visual accuracy of any specific work of art is ultimately a subjective decision. For the remainder of this article, all

Attention allocation and habituation to anger‐related stimuli during a visual search task

A substantial amount of data has accumulated demonstrating that emotionally disordered subjects are prone to bias their attention toward threatening, emotionally relevant stimuli. Little attention has been reserved for the study of cognitive processes involved in anger arousal. In the present study, we investigated whether mood-congruent attentional biases could be demonstrated in subjects of varying levels of trait anger using a visual search task. This task also assessed whether mood-congruent biases diminished with repeated exposure to specific emotion stimuli. To investigate state-trait interaction effects, a naturalistic, anger-inducing insult was administered to half the subjects. There was a positive relation between participants’ level of trait anger and their degree of mood-congruent attentional bias toward anger-related cues only after an insult. As predicted, this effect diminished across blocks of trials. Aggr. Behav. 24:399‐ 409, 1998.

Integers do not automatically activate their quantity representation

Researchers have generally come to the conclusion that integers automatically activate the quantity they symbolize and that this quantity dominates responding. I conducted a strong test of this hypothesis with two numerical same/different experiments. On each trial, I presented the participant an integer between 1 and 9 and asked him or her to identify whether that symbol was a 5. If quantity information dominates responding, participants’ reaction times (RTs) should be a function of the numerical distance between the target and the distractor. If quantity information is not activated, the integer is merely a shape, and participants’ RTs should be a function of the physical similarity of the target and the distractor. The data from Experiments 1 and 2 demonstrate that quantity information exerts no control and that physical similarity is the primary controlling factor. These findings demonstrate that integers maintain a level of independence from their quantity representations.

Look little, look often: The influence of gaze frequency on drawing accuracy

The present article attempts to determine what those who draw accurately do differently than those who do not. Four experiments explore the relation between drawing accuracy and the rate at which artists glance between their drawing and the stimulus (termedgaze frequency). Experiment 1 revealed a positive relation between gaze frequency and drawing accuracy (r2=.33). Experiments 2, 3, and 4 demonstrated that gaze frequency directly influences drawing accuracy. High gaze frequencies may facilitate drawing accuracy by (1) allowing the artist to hold less information in working memory, (2) reducing memory distortion, and (3) facilitating the reduction of context effects through inattentional blindness.

Feature integration that routinely occurs without focal attention.

To analyze visual scenes, the visual system decomposes the visual scene into features that are processed in parallel by separate subsystems. Certain theories (Treisman, Wolfe) propose that these subsystems function independently before focal attention integrates their output. We describe a new paradigm—the gestalt detection task—that directly assesses the degree of preattentive dependence between any two subsystems. We present five experiments that test whether the subsystems that process form and color function independently in processing brief (and, therefore, preattentively processed) stimuli. Our data show that these two subsystems interact during the preattentive processing of featuredependent information. They are synergistic when the information they receive is consistent; they are antagonistic when the information they receive is inconsistent.

How Shape Constancy Relates to Drawing Accuracy

There is increasing evidence that the major source of drawing errors lies in the initial perception of the to-be-drawn object. In four experiments, the authors explore the relation between an artist’s susceptibility to perceptual transformations, as measured by a simple shape constancy task, and drawing accuracy. The data reveal a robust negative relation between errors on the shape constancy task and drawing accuracy in general, and specifically the accuracy of the rendering of spatial relations. The data further suggest that the perceptual processes that lead to errors on the shape constancy task occur during the initial encoding of the stimuli. The authors conclude that the shape constancy task likely measures one’s ability to overcome constructive perception processes that transform the retinal image into a final percept, and that this ability is necessary for the accurate rendering of objects.

Visual detection and perceptual independence: Assessing color and form

Visual stimuli are multidimensional. One important perceptual problem is to determine how the dimensions are combined. One important aspect of dimensional combination is whether the dimensions are perceptually independent or perceptually correlated. A new task is presented—the visual detection task—that directly assesses the degree of perceptual correlation between any two dimensions. Two experiments were conducted that assess the degree of perceptual correlation between form and color during the early stages of perceptual analysis. The results show that form and color are not perceptually independent. In addition, the pattern of perceptual correlation found indicates that form and color are not processed independently. The pattern of results constrains all models of early vision. A model of early vision based on active signal modulation is proposed.

What very small numbers mean

This article presents a theoretical and experimental framework for assessing the biases associated with the interpretation of numbers. This framework consists of having participants convert between different representations of quantities. These representations should include both variations in numerical labels that symbolize quantities and variations in displays in which quantity is inherent. Five experiments assessed how people convert between relative frequencies, decimals, and displays of dots that denote very low proportions (i.e., proportions below 1%). The participants demonstrated perceptual, response, and numerical transformation biases. Furthermore, the data suggest that relative frequencies and decimals are associated with different abstract representations of amount.

Grouping and binding in visual short-term memory.

Findings of 2 experiments are reported that challenge the current understanding of visual short-term memory (VSTM). In both experiments, a single study display, containing 6 colored shapes, was presented briefly and then probed with a single colored shape. At stake is how VSTM retains a record of different objects that share common features: In the 1st experiment, 2 study items sometimes shared a common feature (either a shape or a color). The data revealed a color sharing effect, in which memory was much better for items that shared a common color than for items that did not. The 2nd experiment showed that the size of the color sharing effect depended on whether a single pair of items shared a common color or whether 2 pairs of items were so defined-memory for all items improved when 2 color groups were presented. In explaining performance, an account is advanced in which items compete for a fixed number of slots, but then memory recall for any given stored item is prone to error. A critical assumption is that items that share a common color are stored together in a slot as a chunk. The evidence provides further support for the idea that principles of perceptual organization may determine the manner in which items are stored in VSTM.