One or two? A Process View of pregnancy

Philosophical Studies - How many individuals are present where we see a pregnant individual? Within a substance ontological framework, there are exactly two possible answers to this question. The...     

One blue colour channel or two?

Contrary to the general belief that the yellow-blue mechanism has lower spatial resolution than the red-green mechanism, it has been recently claimed that both mechanisms have similar spatial sensitivity (McKeefry et al, 2001 Vision Research 41 245-255). Studying high-spatial-frequency tritanopia (a colour illusion based on spatio-chromatic interactions in human vision), we found strong evidence for the existence of two blue mechanisms-with low and high spatial-frequency resolution. If confirmed, this may resolve the apparent paradox concerning spatial resolution of the yellow-blue mechanism.     

One,two, or three memories? A problem-solving approach to memory for performed acts

To test three theories of memory for performed acts, four sets of experiments were conducted. Two of the theories, the rehearsal obstruction theory and the multi-code representation theory, posit separate laws for recall of performed acts. The third, a problem-solving theory, attempts to explain act memory as well as memory for visually and verbally presented information within a unified conceptual framework. One set of experiments failed to demonstrate level-of-processing effects with free recall of performed tasks, thus providing evidence in support of the theories assuming distinct laws. The three other sets of experiments, which examined serial recall of performed acts, the effect of specified encoding instructions, and the role of contextual frames in free recall of acts, all gave results in support of the monistic problem-solving interpretation.     

Transcortical motor aphasia: One or two aphasias?

The name "transcortical motor aphasia" has been used to refer to two different types of language alterations: damage in the left supplementary motor area and Luria's dynamic aphasia. It is proposed that they represent two types of language disturbances different enough to be considered two different forms of aphasia.     

Temperature sensitivity: One subjective continuum or two?

An experiment is reported on the effect of six consecutive days of exposure to distortions of binaural time and intensity cues on the localization function for tones of 350, 1000, and 4000 Hz. Tests were conducted under “free-field” conditions. The changes in auditory spatial orientation indicate that adjustments to binaurally distorted temporal and intensive cues can occur. Reorientation does not appear to depend upon the existence of veridical auditory cues.     

One sound or two? Object-related negativity indexes echo perception

The ability to isolate a single sound source among concurrent sources and reverberant energy is necessary for understanding the auditory world. The precedence effect describes a related experimental finding, that when presented with identical sounds from two locations with a short onset asynchrony (on the order of milliseconds), listeners report a single source with a location dominated by the lead sound. Single-cell recordings in multiple animal models have indicated that there are low-level mechanisms that may contribute to the precedence effect, yet psychophysical studies in humans have provided evidence that top-down cognitive processes have a great deal of influence on the perception of simulated echoes. In the present study, event-related potentials evoked by click pairs at and around listeners' echo thresholds indicate that perception of the lead and lag sound as individual sources elicits a negativity between 100 and 250 msec, previously termed the object-related negativity (ORN). Even for physically identical stimuli, the ORN is evident when listeners report hearing, as compared with not hearing, a second sound source. These results define a neural mechanism related to the conscious perception of multiple auditory objects.     

Looking for two targets at the same time: One search or two?

A considerable amount of evidence suggests that, under conditions of high discriminability, subjects are able to process multiple elements in a visual display simultaneously when searching for a single target among distractors. Relatively little emphasis, however, has been placed on the question of whether subjects can search for and detect multiple targets simultaneously. This latter question is the focus of the present report. In two experiments, we compare performance in single-target and multiple-target detection tasks in order to investigate whether or not multiple targets can be detected simultaneously. In Experiment 1, subjects searched for one or two targets that were defined by color. In Experiment 2, subjects searched for a color and/or a letter target. When the two targets were presented in the same location (e.g., a red X when Target 1 was red and Target 2 was an X), they seemed to be detected simultaneously. Implications for object-based processing of visual information are discussed.     

The conjunction fallacy? A reply to Bar-Hillel

In her commentary on our article, Bar-Hillel (1991) argues that our normative interpretation of the Lindaproblem is inaccurate and that the representativeness heuristic can account for all of the relevant data. I argue that the normative interpretation of the Linda problem remains slippery and that representativeness fails to account for much of the data. Furthermore, substantial evidence supports our suggestion that subjects use different underlying models in estimating likelihoods in different con problems.     

Content-blind norms, no norms, or good norms? A reply to Vranas

In the psychology of thinking, little thought is given to what constitutes good thinking. Instead, normative solutions to problems have been accepted at face value, thereby determining what counts as a reasoning fallacy. I applaud Vranas (Cognition 76 (2000) 179) for thinking seriously about norms. I do, however, disagree with his attempt to provide post hoc justifications for supposed reasoning fallacies in terms of 'content-neutral' norms. Norms need to be constructed for a specific situation, not imposed upon it in a content-blind way. The reason is that content-blind norms disregard relevant structural properties of the given situation, including polysemy, reference classes, and sampling. I also show that content-blind norms can, unwittingly, lead to double standards: the norm in one problem is the fallacy in the next. The alternative to content-blind norms is not no norms, but rather carefully designed norms.     

Instrumental and expressive representations of aggression: One scale or two?

The Expagg questionnaire was developed to measure a subject's view of their own aggression as a relatively instrumental or relatively expressive act. Two issues have been raised pertaining to the dimensional structure of the questionnaire: the use of principal components analysis on dichotomous responses and the possibility that instrumental and expressive representations might be independent dimensions rather than opposite ends of a single continuum. In study 1, dichotomous Expagg data from 405 subjects were subjected to microfact, principal components, and factor analysis. Each produced a first general factor, and the correlations between the item loadings were in excess of r = .99. In study 2, a 40‐item Likert scale version of Expagg was given to 295 subjects. Principal components analysis, paired item correlations, and subscale correlations suggested partial independence of instrumental and expressive items. Two new 8‐item scales measuring instrumental and expressive representations were constructed that maximise their independence. Potential uses of these revised scales are discussed. Aggr. Behav. 25:435–444, 1999. © 1999 Wiley‐Liss, Inc.     

One table or two? scientific anti-realism and Husserl’s phenomenology

Continental Philosophy Review - In this study I argue that Husserl’s phenomenology is compatible with a realistic interpretation of scientific theories. That said, I distinguish between the...     

Visual short-term memory for two sequential arrays: One integrated representation or two separate representations?

Two dot arrays, each containing a different set of six randomly selected locations from a 5 × 5 matrix, were presented briefly and were separated by an interstimulus interval (ISI) of 0, 200, 500, or 1,500 msec. Subjects were asked to remember these locations and to report whether a probe dot matched the locations in memory. To find out whether the subjects had formed an integrated representation of the two arrays, the probe dot was accompanied by matrix elements from the first array, from the second array, or from both arrays. Memory for Array 1 was significantly impaired when the retrieval context was drawn from Array 2, and vice versa, suggesting that the two arrays were represented separately. This effect was observed only at an ISI of 500 msec or longer. We propose that as Array 1 is better consolidated, its representation becomes more separated from that of Array 2.     

Interference in memory by process or content? A reply to Neath (2000)

The approach to the irrelevant sound effect by Neath (2000) is discussed in terms of the contrast between content-based and process-based interference. Four themes are highlighted: First, problematic features of the feature model are highlighted; second, results not considered by Neath are presented; third, empirical underpinnings of the feature model not related to the irrelevant-sound effect are questioned; last, the parsimony of the feature model is questioned. The balance of the evidence seems to be in favor of a process-based approach, on the grounds that it provides a comprehensive account of acoustic and taskbased factors within the irrelevant sound effect, for both speech and nonspeech sound.