Suzanne M. Delaney

Implicit memory for unfamiliar objects depends on access to structural descriptions

We investigated implicit memory for unfamiliar objects with a task in which subjects decided whether structurally possible and impossible line drawings could exist in three-dimensional space. In Experiment 1, significant priming effects on object decision performance were observed after encoding of global, three-dimensional object structure but not local, two-dimensional object features. Explicit memory did not differ significantly as a function of global vs. local study processing. In Experiments 2 and 3, elaborative encoding had different effects on object decision and recognition performance, thus providing evidence for functional dissociation between implicit and explicit memory. Stochastic independence between object decision and recognition performance was also observed. Results were consistent with the hypothesis that implicit memory, as indexed by priming on the object decision task, depends on encoding of and access to structural descriptions of objects.

Automatic (prelexical) phonetic activation in silent word reading: Evidence from backward masking

Abstract Visual access to a printed word may be accompanied by a very rapid activation of phonetic properties of the word as well as its constituent letters. We suggest that such automatic activation during word identification, rather than only postlexical recoding, routinely occurs in reading. To demonstrate such activation, we varied the graphemic and phonetic properties shared by a word target and a following pseudoword mask. Graphemic ( mard ) and homophonic ( mayd ) masks, equated for number of letters shared with a word target ( made ), both showed a masking reduction effect relative to a control mask. There was an additional effect of the homophonic mask over the graphemic mask, attributable to phonetic activation. A second experiment verified this pattern of mask reduction effects using conditions that ruled out any explanation of the effect that does not take account of the target-mask relationship. We take the results to suggest that a phonetic activation nonoptionally occurs (prelexically) during lexical access.

Implicit memory for possible and impossible objects: constraints on the construction of structural descriptions

Four experiments examined implicit memory or priming effects on an object decision task in which subjects decided whether structurally possible or impossible novel objects could exist in three-dimensional form. Results revealed equivalent levels of priming for possible objects after 1 vs. 4 5-s exposures to the same structural encoding task (Experiment 1) and when objects were studied with a single structural encoding task or 2 different structural encoding tasks (Experiment 3). Explicit memory, by contrast, was greatly affected by both manipulations. However, priming of possible objects was not observed when Ss were given only a single 1-s exposure to perform a structural encoding task (Experiment 2). No evidence for priming of impossible objects was observed in any of the 4 experiments. The data suggest that object decision priming depends on a presemantic structural description system that is distinct from episodic memory.

Implicit memory for visual objects and the structural description system

Several experiments are described in which priming or implicit memory for visual objects was investigated. In one set of studies, subjects were shown line drawings of unfamiliar objects that were either structurally possible or structurally impossible. Implicit memory was assessed with a possible/impossible object-decision task, and explicit memory was assessed with a recognition task. The results revealed significant priming for possible objects following study tasks that required encoding of three-dimensional object structure; semantic/elaborative study processing enhanced explicit but not implicit memory. No priming of impossible objects was found. An experiment using familiar objects also revealed that priming, but not explicit memory, was independent of semantic/elaborative study processing. It is suggested that priming of visual objects depends on a presemantic system that is dedicated to the representation of object form and structure and can function independently of episodic memory.

Priming of nonverbal information and the nature of implicit memory

Publisher Summary This chapter reviews existing evidence on priming of nonverbal information, discusses methodological, conceptual, and theoretical issues that arise from this research, and sketches a preliminary framework for conceptualizing relevant phenomena that integrates implicit memory research with recent neuropsychological studies of perceptual disorders that are produced by brain damage. There is a description of implicit memory in the chapter as the unintentional retrieval of information that was acquired during a specific episode on tests, which do not require conscious recollection of that episode. Systematic investigation of implicit memory represents a relatively new research direction in cognitive psychology and neuropsychology. Psychological studies have been traditionally concerned with explicit memory-intentional, conscious recollection of recent events-as expressed on standard recall and recognition tests. It discusses that there has been a virtual explosion of research concerning various kinds of implicit memory, stimulated largely by studies that have shown that implicit memory can be dissociated sharply from explicit remembering. The dissociations have been produced both by a variety of experimental manipulations in normal subjects and by demonstrations that amnesic patients show intact implicit memory despite impaired explicit memory. Various forms of learning and retention can be grouped under the general descriptive heading of “implicit memory,” including such phenomena as skill learning and conditioning.

Pragmatic Factors in Making and Understanding Promises.

Within his theory of speech acts, Searle (1965, 1969) has suggested that certain conditions must hold true for a promise to be successfully made. These include: (a) that the speakers utterance place him or her under an obligation to fulfill the promise because it is conventionally recognized as a promise; (b) that promises can be made only in situations where the addressee prefers that the speaker do the action promised; and (c) that the promise cannot be made in contexts where the speaker would have done the promised action in the normal course of events. We examined peoples intuitions regarding these pragmatic conditions by looking at how people make and understand promises. The results from three studies showed that the first two of Searles conditions are extremely important to maintain if a promise is to be made or understood. However, it appears that people can make promises about actions that would be performed in the normal course of events. As such, these studies support the idea that promises ...

Stimulus motion increases measured visual field extent in children 3.5 to 30 Months of age

Purpose To examine the influence of stimulus motion on measured visual field extent of 3.5- to 30-month-old children and adults. Methods Each subject was tested with LED-hybrid and LED-kinetic perimetry procedures, using a black double-arc perimeter. Targets in both procedures were identical in size, color, luminance, contrast, and flicker rate. However, in the LED-hybrid procedure, peripheral targets were sequentially illuminated from more peripheral to more central locations, whereas in the LED-kinetic procedure, a peripheral target on a black wand was manually moved centrally along the perimeter arm. A subset of subjects was also tested with white sphere kinetic perimetry (WSKP). Results The LED-kinetic procedure produced larger measured visual field extent than the LED-hybrid procedure in 3.5-, 11-, 17-, and 30-month-olds, but not in 7-month-olds or adults. Data from subjects tested with WSKP indicated that both stimulus motion and discrepancies in scoring methods contributed to the difference reported previously between visual field measurements obtained with WSKP vs. LED-hybrid perimetry. Conclusion In infants and toddlers, measured visual field extent is larger for moving than for nonmoving targets. Further research is needed to determine whether the effect of motion is related to the visual system or to attentional factors.

The Influence of Stimulus Size on Measured Visual Field Extent in Infants

Purpose. To compare measured visual field extent for a 6° stimulus (typical size used in studies of infants) with a 1.5° stimulus (similar to the largest size used in Goldmann perimetry) in young infants. Methods. A total of 120 infants (60 each at 3.5 months and 7 months of age) and 24 adults were tested monocularly with a kinetic perimetry procedure using a black double-arc perimeter. Each subject was tested with either a 6° or 1.5° white sphere, which was mounted on a black wand and moved smoothly toward the intersection of the perimeter arms at 3.4°/s. Visual field extent along each perimeter arm was defined as the median of 2 to 3 measurements of the position of the leading edge of the stimulus when the subject made an eye movement toward the stimulus. Results. The 6° stimulus produced larger measured visual field extent than the 1.5° stimulus in 3.5-month olds (temporal field only) and in 7-month olds (nasal and temporal field), but not in adults. Conclusions. Using the testing conditions of the present study, increasing stimulus size beyond the largest used in a Goldmann perimeter (∼2°) increases measured visual field extent in young infants, but not in adults. This may relate to differences in peripheral summation areas or to differences in attentional factors between infants and adults.

Measured visual field extent varies with peripheral stimulus flicker rate in very young children.

Purpose. The purpose of this article is to describe measured visual field extent in very young children in response to variation in peripheral stimulus flicker rate. Methods. Binocular visual field extent was measured using a black, double-arc perimeter and an LED static perimetry procedure in 120 11-month-old, 120 17-month-old, and 120 30-month-old children and 40 adults. Each subject was tested with one of four flicker rates: 1 Hz, 10 Hz, 20 Hz, or 40 Hz. An interpolated estimate of the eccentricity at which 50% of subjects detected the peripheral stimulus and the mean of the farthest eccentricity at which subjects detected the peripheral stimulus were calculated for each flicker rate for each age group. Results. In 11-, 17-, and 30-month-old children, but not in adults, measured visual field extent (eccentricity at which the stimulus was detected) varied significantly with rate of stimulus flicker. The largest measured visual field extent was produced by a 10-Hz stimulus and the smallest was produced by 1-Hz and 40-Hz stimuli. Measured visual field extent in children was similar to that of adults for 10-Hz flicker, but smaller than that of adults for 1-Hz, 20-Hz, and 40-Hz flicker. Conclusions. These results underscore the importance of standardizing stimulus parameters when developing tests for clinical assessment of visual fields in children. Furthermore, for longitudinal assessment of young patients, use of a 10-Hz flicker rate, in combination with the other parameters used in the present study, would help to avoid difficulties in interpretation that could arise from an interaction between age-related and disease-related changes that might occur if other stimulus flicker rates were used.

Does rate of stimulus presentation affect measured visual field extent in infants and toddlers

PURPOSE To evaluate the effect of stimulus presentation rate on the measurement of visual field extent in infants and toddlers. METHODS Visual field extent was measured for 300 children (N = 60 at 3.5, 7, 11, 17, and 30 months) and 24 adults using hybrid static-kinetic perimetry. Flickering light-emitting diode (LED) stimuli were illuminated sequentially, peripherally to centrally at 10.2 degrees intervals, along 4 diagonal meridia at 2 stimulus presentation rates: 2 s/stimulus (equivalent to 5 degrees/s) and 3 s/stimulus (equivalent to 3 degrees/s). Rate of presentation was a between-subjects variable. RESULTS No effect of stimulus presentation rate was found for adults. The faster rate of stimulus presentation yielded smaller measured visual field extent for children between the ages of 7 and 30 months. The apparent difference seen with 3.5-month-olds did not reach significance. CONCLUSIONS Faster rates of stimulus presentation may result in underestimation of visual field extent in children between the ages of 7 and 30 months.