Descartes on the distinction between primary and secondary qualities

ABSTRACT

Descartes did not use the terms ‘primary’ and ‘secondary’ qualities, but a similar distinction emerges from his texts: certain qualities of objects (such as size and shape) are intrinsic properties of matter, whereas others (like colours and smells) are products of the interaction with a perceiver. A common interpretation states that the division between primary and secondary qualities is explained by the way in which we are acquainted with them: an idea of a primary quality is similar to its physical causes, and it is clearly and distinctly perceived by the intellect. An idea of a secondary quality is dissimilar to its physical causes and it is obscurely and confusedly perceived by the senses. This view receives the name of ‘bifurcation reading’ (Simmons, A. ‘Descartes on the Cognitive Structure of Sensory Experience’. Philosophy and Phenomenological Research, LXVII, no. 3 (November 2003)). While it integrates well some textual occurrences, it creates a problematic fragmentation within single acts of perception. This paper contends that this reading is incorrect. It presents several arguments for the claim that the distinction of qualities is due to the different ways in which our ideas of them misrepresent their physical causes. Then, Descartes’ dissimilarity thesis between physical objects and our ideas of them remains a structural feature of his theory of sensory perception and not a local phenomenon affecting only ideas of secondary qualities.     

Mental imagery and pictorial memory

Previous research has failed to show consistent effects upon memory performance of individual differences in the use of mental imagery. A test of pictorial memory was devised which varied the ease with which the stimulus patterns could be verbally encoded. A factor analysis related performance in this task to a variety of other individual characteristics. The recall of material which could not be readily verbalized defined a factor within the solution which showed significant loadings of age and performance in the Progressive Matrices, but not of subjective ratings of the vividness of experienced imagery. The recall of material which could be readily verbalized did not contribute to the factorial structure of the results. It was concluded that the two sorts of pictorial material are remembered in quite different ways.     

On the distinction between sensory storage and short-term visual memory

A pattern made by randomly filling cells in a square matrix was presented for 1 see and followed, after various intervals, by an identical or similar pattern. Ss responded “same” or “different.” Performance was fast and accurate if the interval was short and there was no movement or masking of the pattern during the interval. Performance was slower, less accurate, and highly dependent on pattern complexity if the interval exceeded 100 msec or if there was movement or masking. The results are interpreted as evidence for two distinct classes of visual memory: high-capacity sensory storage which is tied to spatial position and is maskable and brief; and schematic short-term visual memory which is not tied to spatial position, which is protected against masking, and which becomes less effective over the first few seconds but not over the first 600 msec.     

Psychobiological evidence for the distinction between episodic and semantic memory

The evidence for discrete neurobiological mechanisms that underlie episodic and semantic memory is reviewed. Published data from three separate lines of research are considered: studies of human amnesic patients, psychopharmacological studies of normal human subjects, and studies of working and reference memory in rodents, a distinction that is arguably analogous to the episodic/semantic dichotomy. It is concluded that the available evidence does not indicate that episodic and semantic memory are mediated by discrete neural subsystems. An alternative model of human memory is discussed, based on the concept of parallel distributed processing.An earlier version of this paper was submitted as part of the author's qualifying examination at Emory University.     

Validating a distinction between primary and secondary psychopathy with measures of Gray's BIS and BAS constructs

Investigators commonly distinguish between primary and secondary psychopathy (H. Cleckley, 1976; D.T. Lykken, 1995), though there is a lack of consensus regarding the best means to achieve this distinction. To address the validity of using R. D. Hare's (2003) Psychopathy Checklist and the G. Welsh (1956) Anxiety Scale for this purpose, the authors used 2 measures of J. A. Gray's (1987) behavioral inhibition system/behavioral activation system (BIS/BAS). Following D. T. Lykken (1995) and D. C. Fowles (1980), the authors hypothesized that primary psychopathy would be associated with a weak BIS and a normal BAS, whereas secondary psychopathy would be associated with a strong BAS and a normal BIS. Results for primary psychopathy were as predicted. Results for secondary psychopathy clearly supported the strong BAS prediction but provided mixed support for the normal BIS prediction.     

Mental imagery in a visuospatial working memory task and modulation of activation

Ability to process information during a mental imagery task relying on visuospatial working memory and the advantages offered by the possibility of focusing the activation on specific items were examined in younger and older adults. The mental imagery task used for the study required participants to mentally move on a two-dimensional (5×5) or three-dimensional (3×3×3) matrix, while having to hold in memory either the whole pathway (WP condition) or just the final position reached (FP condition). The results revealed age-related differences in ability to modulate activation of visuospatial information. In particular, older adults, unlike the younger counterparts, did not benefit when the task allowed just part of the presented material to be considered. In particular, they drew less advantage from the three-dimensional matrix than the younger group. The findings are discussed in terms of the importance of processes reducing visuospatial working memory activation of irrelevant information and of the difficulties encountered by older adults in the modulation of activation.     

Mental imagery and fiction

Fictions evoke imagery, and their value consists partly in that achievement. This paper offers analysis of this neglected topic. Section 2 identifies relevant philosophical background. Section 3 offers a working definition of imagery. Section 4 identifies empirical work on visual imagery. Sections 5 and 6 criticize imagery essentialism, through the lens of genuine fictional narratives. This outcome, though, is not wholly critical. The expressed spirit of imagery essentialism is to encourage philosophers to ‘put the image back into the imagination’. The weakened conclusion is that while an image is not essential to imagining, it should be returned to our theories of imagination.     

Mental imagery and the third dimension

What sort of medium underlies imagery for three-dimensional scenes? In the present investigation, the time subjects took to scan between objects in a mental image was used to infer the sorts of geometric information that images preserve. Subjects studied an open box in which five objects were suspended, and learned to imagine this display with their eyes closed. In the first experiment, subjects scanned by tracking an imaginary point moving in a straight line between the imagined objects. Scanning times increased linearly with increasing distance between objects in three dimensions. Therefore metric 3-D information must be preserved in images, and images cannot simply be 2-D "snapshots." In a second experiment, subjects scanned across the image by "sighting" objects through an imaginary rifle sight. Here scanning times were found to increase linearly with the two-dimensional separations between objects as they appeared from the original viewing angle. Therefore metric 2-D distance information in the original perspective view must be preserved in images, and images cannot simply be 3-D "scale-models" that are assessed from any and all directions at once. In a third experiment, subjects mentally rotated the display 90 degrees and scanned between objects as they appeared in this new perspective view by tracking an imaginary rifle signt, as before. Scanning times increased linearly with the two-dimensional separations between objects as they would appear from the new relative viewing perspective. Therefore images can display metric 2-D distance information in a perspective view never actually experiences, so mental images cannot simply be "snapshot plus scale model" pairs. These results can be explained by a model in which the three-dimensional structure of objects is encoded in long-term memory in 3-D object-centered coordinate systems. When these objects are imagined, this information is then mapped onto a single 2-D "surface display" in which the perspective properties specific to a given viewing angle can be depicted. In a set of perceptual control experiments, subjects scanned a visible display by (a) simply moving their eyes from one object to another, (b) sweeping an imaginary rifle sight over the display, or (c) tracking an imaginary point moving from one object to another. Eye-movement times varied linearly with 2-D interobject distance, as did time to scan with an imaginary rifle sight; time to tract a point varied independently with the 3-D and 2-D interobject distances. These results are compared with the analogous image scanning results to argue that imagery and perception share some representational structures but that mental image scanning is a process distinct from eye movements or eye-movement commands.     

Relationship between relaxation by guided imagery and performance of working memory

This study tested the hypothesis that relaxation by guided imagery improves working-memory performance of healthy participants. 30 volunteers (both sexes, ages 17-56 years) were randomly assigned to one of three groups and administered the WAIS-III Letter-Number Sequencing Test before and after 10-min. treatment with guided imagery or popular music. The control group received no treatment. Groups' test scores were not different before treatment. The mean increased after relaxation by guided imagery but not after music or no treatment. This result supports the hypothesis that working-memory scores on the test are enhanced by guided imagery and implies that human information processing may be enhanced by prior relaxation.     

Working memory and the vividness of imagery

The working memory framework was used to investigate the factors determining the phenomenological vividness of images. Participants rated the vividness of visual or auditory images under control conditions or while performing tasks that differentially disrupted the visuospatial sketchpad and phonological loop subsystems of working memory. In Experiments 1, 2, and 6, participants imaged recently presented novel visual patterns and sequences of tones; ratings of vividness showed the predicted interaction between stimulus modality and concurrent task. The images in experiments 3, 4, 5, and 6 were based on long-term memory (LTM). They also showed an image modality by task interaction, with a clear effect of LTM variables (meaningfulness, activity, bizarreness, and stimulus familiarity), implicating both working memory and LTM in the experience of vividness.     

Contextual imagery in meaning and memory

Three hundred homonyms were selected, and sentence fragments were written to emphasize two meanings of each. The words were rated on image-arousing capacity both in and out of context and on frequency of occurrence in context. Imagery values for the words out of context were predicted quite well by an average of the contextual imagery ratings, weighted by their relative frequencies. The finding is consistent with the hypothesis that words presented in isolation are interpreted in specific senses according to a frequency bias, with imagery ratings reflecting those senses. In a memory experiment. words were selected to vary orthogonally on both contextual and out-of-context imagery. Recall of words in isolation was a function of out-of-context imagery, while recall of words presented in context was a function of contextual imagery, further supporting the hypothesis.     

Mental imagery, reasoning, and blindness

Although reasoning seems to be inextricably linked to seeing in the “mind's eye”, the evidence is equivocal. In three experiments, sighted, blindfolded sighted, and congenitally totally blind persons solved deductive inferences based on three sorts of relation: (a) visuo-spatial relations that are easy to envisage either visually or spatially, (b) visual relations that are easy to envisage visually but hard to envisage spatially, and (c) control relations that are hard to envisage both visually and spatially. In absolute terms, congenitally totally blind persons performed less accurately and more slowly than the sighted on all such tasks. In relative terms, however, the visual relations in comparison with control relations impeded the reasoning of sighted and blindfolded participants, whereas congenitally totally blind participants performed the same with the different sorts of relation. We conclude that mental images containing visual details that are irrelevant to an inference can even impede the process of reasoning. Persons who are blind from birth—and who thus do not tend to construct visual mental images—are immune to this visual-impedance effect.     

Mental imagery,reasoning, and blindness

Although reasoning seems to be inextricably linked to seeing in the “mind's eye”, the evidence is equivocal. In three experiments, sighted, blindfolded sighted, and congenitally totally blind persons solved deductive inferences based on three sorts of relation: (a) visuo-spatial relations that are easy to envisage either visually or spatially, (b) visual relations that are easy to envisage visually but hard to envisage spatially, and (c) control relations that are hard to envisage both visually and spatially. In absolute terms, congenitally totally blind persons performed less accurately and more slowly than the sighted on all such tasks. In relative terms, however, the visual relations in comparison with control relations impeded the reasoning of sighted and blindfolded participants, whereas congenitally totally blind participants performed the same with the different sorts of relation. We conclude that mental images containing visual details that are irrelevant to an inference can even impede the process of reasoning. Persons who are blind from birth—and who thus do not tend to construct visual mental images—are immune to this visual-impedance effect.     

Kinetic and static imagery in sentence memory

This experiment investigates the possibility that two different kinds of imagery codes are used in sentence memory, one involving moving images (kinetic imagery) and the other involving stationary images (static imagery). Using a modality-specific interference task it was shown that only sentences involving kinetic imagery were affected by the visual interference task; neither static nor low imagery sentences were so affected. The results are interpreted as showing that some kind of imaginal code is used in memory, but that there are different kinds of code available. It is claimed that this result is inconsistent both with Paivio's (1971) ‘dual-coding’ hypothesis and with propositional accounts of sentence memory.     

On the distinction between perception and cognition

To uphold the distinction between perception and cognition for certain classes of tasks or phenomena, it is proposed that three criteria must be met: (1) when perceptual and cognitive functions serve different biological purposes, (2) when stimulus information in dynamic events is necessary, but not sufficient for veridical perception, and (3) when the task emphasizes explicit retrieval, as opposed to implicit use of information. Conversely, when the three criteria have not been met, conditions for theoretical unification exist.     

Short-term memory differences between children predict imagery effects when sentences are read

Children in Grades 4 through 6 read concrete sentences that they were asked to learn. Half the subjects were instructed to construct images representing the sentence meanings. The remaining participants were provided no strategy instructions (control condition). Individual differences in short-term memory were more highly associated with performance in the imagery than in the control condition. There was a clear positive effect of imagery instructions on learning efficiency among students with relatively greater short-term memory; there was no difference in learning efficiency between the imagery and control conditions among students below the median for short-term memory performance. All relevant analyses supported the conclusion that imaginal coding of sentences that are read is demanding of short-term memory capacity.