Attention and relative novelty in human perceptual learning

Four experiments examined the role of attention in human perceptual learning. In Experiment 1, participants were preexposed to a pair of visual (checkerboard) stimuli AX and BX, with common elements X and unique features A and B. A same-different task was then used to assess discrimination of AX and BX and a pair of control stimuli, CY and DY. In addition, participants' eye movements were recorded to assess the role of attentional processes. The results showed that preexposure enhanced discrimination between AX and BX. Furthermore, participants showed greater attention to the preexposed unique features A and B than to the novel unique features C and D, as measured by the eye gaze monitor. Experiments 2 and 3 examined the prediction that perceptual learning is due to the relative familiarity of the common and unique stimulus features. Experiment 4 replicated the intermixed-blocked effect and showed that the way in which AX and BX are presented is also important for perceptual learning. The results generally support the idea that intermixed preexposure to AX and BX increases attention to the unique stimulus features A and B. Some aspects of the results are consistent with a relative novelty account, whereas others implicate a high-level attentional process that is not driven by stimulus novelty.     

Absolute identification by relative judgment

In unidimensional absolute identification tasks, participants identify stimuli that vary along a single dimension. Performance is surprisingly poor compared with discrimination of the same stimuli. Existing models assume that identification is achieved using long-term representations of absolute magnitudes. The authors propose an alternative relative judgment model (RJM) in which the elemental perceptual units are representations of the differences between current and previous stimuli. These differences are used, together with the previous feedback, to respond. Without using long-term representations of absolute magnitudes, the RJM accounts for (a) information transmission limits, (b) bowed serial position effects, and (c) sequential effects, where responses are biased toward immediately preceding stimuli but away from more distant stimuli (assimilation and contrast).     

Egocentric and relative spatial codes in S-R compatibility

Summary It has been shown that spatial compatibility is due to a comparison between the spatial codes that describe stimulus and response positions. Such codes are often defined in right-left terms. There are, however, two types of right-left codes that can be used for describing a position in space. One is formed with relation to the egocentric axes and can be termed side, whereas the other is formed with relation to an external reference location and can be termed relative position. Five experiments were conducted to determine the role of these different codes in producing spatial compatibility effects. In Experiments 1 and 2 the position of the stimulus provided the relevant cue for choosing the correct response (i.e., the situation was typical of spatial compability proper), whereas in Experiments 3, 4, and 5 the stimulus provided a locational cue that was not necessary for choosing the correct response (i.e., the situation was typical of the Simon effect). The experimental manipulations concerned the task demands and the time elapsing between availability of the stimulus code and availability of the response code. The results showed that upon stimulus presentation, both stimulus codes (that concerning side and that concerning relative position) were formed, but experimental manipulations determined the one that was effective in yielding compatibility effects. When the task required the use of one type of code, then spatial compatibility depended on that code alone. When the two coding processes were separated in time, then spatial compatibility depended only on the code that was formed simultaneously with the response code.     

A common perceptual parameter for stair climbing for children,young and old adults

In this paper we examine whether a common perceptual parameter is available for guiding old adults, young adults and children in climbing the highest stair mountable in a bipedal fashion. Previous works have shown that the ratio between the height of the stair and the hip height was the body-scaled invariance adopted as information for selecting the highest stair by young adults [Journal of Experimental Psychology: Human Perception and Performance 10 (1984) 683-703] but not by older adults [Journal of Experimental Psychology: Human Perception and Performance 3 (1992) 691-697]. Indeed, for older adults additional bio-mechanical parameters needed to be added to the model due to their decrease in leg strength and flexibility.Up to now, no perceptual invariant has been identified yet for determining the relevant information used for guiding the stair climbing action for normal healthy people. We propose a new parameter as the angle defined by the ratio between the height of the stair and the distance taken from the feet to the top edge of the stair before the initiation of the movement. We show that this angle is the same for children, young adults and older adults despite the different kinematics of the motion, the anthropometrics and the skill ability exhibit by the participants. In summary we show that even when the climbability judgments, based on the simple ratio leg length-stair height, are influenced by differences in age, participants use a common perceptual variable when they are coordinating their stair climbing action.     

Absolute and relative measures of dimensional contrast.

Two sets of experiments examined the discriminative performance of pigeons on a visual flicker-rate continuum using a maintained generalization procedure. In the first experiment, responses during the intermediate stimulus value were not reinforced, whereas responses during all other stimuli were reinforced periodically. In the second experiment, training was similar to the first, with the exception of one condition in which stimuli adjacent to the negative stimulus border were eliminated from the discrimination set. Results from both experiments show that positive dimensional contrast seems to represent a relative enhancement of discrimination gradient form, rather than an absolute increase in responding with respect to prior baseline. Further, the form and magnitude of positive dimensional contrast are not predictable from the form and magnitude of baseline response rates. Results from the second experiment indicate that eliminating border stimuli increased response-rate differences between positive and negative stimuli, but did not necessarily diminish the magnitude of positive dimensional contrast.     

Effects of perceptual and conceptual similarity in lexical priming of young children who stutter: preliminary findings

The purpose of this study was to investigate the influence of conceptual and perceptual properties of words on the speed and accuracy of lexical retrieval of children who do (CWS) and do not stutter (CWNS) during a picture-naming task. Participants consisted of 13 3–5-year-old CWS and the same number of CWNS. All participants had speech, language, and hearing development within normal limits, with the exception of stuttering for CWS. Both talker groups participated in a picture-naming task where they named, one at a time, computer-presented, black-on-white drawings of common age-appropriate objects. These pictures were named during four auditory priming conditions: (a) a neutral prime consisting of a tone, (b) a word prime physically related to the target word, (c) a word prime functionally related to the target word, and (d) a word prime categorically related to the target word. Speech reaction time (SRT) was measured from the offset of presentation of the picture target to the onset of participant's verbal speech response. Results indicated that CWS were slower than CWNS across priming conditions (i.e., neutral, physical, function, category) and that the speed of lexical retrieval of CWS was more influenced by functional than perceptual aspects of target pictures named. Findings were taken to suggest that CWS tend to organize lexical information functionally more so than physically and that this tendency may relate to difficulties establishing normally fluent speech and language.

Educational objectives: The reader will learn about and be able to (1) communicate the relevance of examining lexical retrieval in relation to childhood stuttering and (2) describe the method of measuring speech reaction times of accurate and fluent responses during a picture-naming task as a means of assessing lexical retrieval skills.     

The comprehension of relative,absolute, and contrastive adjectives by young children

Three types of adjectives-relative, contrastive, and absolute-were presented in standard and comparative contrasts to preschool children in a picture-choice paradigm. Proportion of errors in picture choices showed the predicted effect of greater difficulty for comparative than for standard terms. Latency data showed that the responses to comparative forms of absolute and contrastive adjectives were significantly slower than responses to their standard forms, and were also slower than responses to the comparative forms of the relative terms which did not differ from their standard forms. These data support the interpretation that the classes of relative, contrastive, and absolute adjectives are processed differently by young children. Factors of cognitive complexity that influence the order of difficulty are considered.     

Orientation relative to the retina determines perceptual organization

Two experiments are reported which show that perceptual unit formation, as measured by Gillam’s method of using common reversals of ambiguous lines as an index of their coherence, depends strongly on the orientation of the configuration. Measurements under conditions of 90° head and body tilt show that the critical orientation is retinal, not physical. The results are discussed in relation to other findings and to possible explanations.     

Absolute and relative effects of similarity and distance on grouping

Four experiments are reported, the aim of which was to explore the achromatic-colour and distance relations that determine the probability of achromatic surfaces grouping perceptually. The first two experiments were performed to test Wertheimer's conjecture that similarity and dissimilarity of achromatic colours jointly determine grouping. The results indicate that only similarity of achromatic colours determines grouping. Data from the other two experiments show that grouping is determined by absolute, relative, and Gillam's distances. These findings agree with previous literature showing that different algorithms or mechanisms determine grouping by similarity and grouping by distance. Additionally, these findings show that the single factor of grouping by distance also depends on multiple algorithms or mechanisms.     

Rats can make relative perceptual judgments about sequential stimuli

In their natural environment, animals often make decisions based on abstract relationships among multiple stimulus representations. Humans and other primates can determine not only whether a sensory stimulus differs from a remembered sensory representation, but also how they differ along a particular dimension. However, much remains unknown about how such relative comparisons are made, and which species share this capacity, in part because most studies of sensory-guided decision making have utilized instrumental tasks in which choices are based on very simple stimulus-response associations. Here, we used a two-stimulus-interval discrimination task to test whether rats could determine how two sequentially presented stimuli were related along the dimension of odor quality (i.e., what the stimulus smells like). At a central port, rats sampled and compared two odor mixtures that consisted of spearmint and caraway in different ratios, separated by a 2-4-s interval, and then entered the left or right reward port. Water was delivered at the left if the first mixture consisted of more spearmint than the second did, and at the right otherwise. We found that the difference in mixture ratio predicted choice accuracy. Control experiments suggest that rats were indeed basing their choices on a comparison of odor quality across mixtures and were not using associative strategies. This study is the first demonstration of the use of a sequential "more than versus less than" rule in rats and provides a well-controlled paradigm for studying abstract comparisons in a rodent model system.     

A model of perceptual classification in children and adults

The developmental trend from overall-similarity to dimensional-identity classifications is explained by a quantitative model. I begin with the assumption that objects are represented in terms of constituent dimensions and that the representation of objects changes little with development. Given this assumption, the model has three major parts. First, the similarity between objects is a function of the combination of the constituent dimensional differences. I propose developmental change in the likelihood that dimensions are differentially weighted in the calculation of similarity. Second, the perceived similarities between objects are valued for the purpose of constructing classifications. I propose that similarities are valued more dichotomously with age, such that identity becomes increasingly special. Third, the valued similarities are used to choose the best classification of those possible. The model provides good qualitative fits to the extant data. Three experiments examining classifications in 2- to 8-year-olds and in adults support specific new claims of the model. The data and the model provide new insights about development, classification, and similarity.     

Absolute and relative cues for the auditory perception of egocentric distance

Three experiments were performed to examine the reverberation cue to egocentric auditory distance and to determine the extent to which such a cue could provide 'absolute', as contrasted with 'relative', information about distance. In experiment 1 independent groups of blindfolded observers (200 altogether) were presented with broadband noise from a speaker at one of five different distances (0.55 to 8 m) in a normal hard-walled room. Half of each group of observers were presented with the sound at 0 deg azimuth, followed (after a delay) by the identical sound at 90 deg azimuth. The order of presentation was reversed for the remaining observers. Perceived distance varied significantly as a function of the physical distance to the speaker, even for the first presentations. The change in the binaural information between the 0 deg and 90 deg presentations did not significantly modify the results. For both orientations, near distances were overestimated and far distances were underestimated. Experiment 2 and 3 were designed to evaluate how much prior auditory exposure to the laboratory environment was necessary. A 200 Hz square-wave signal was presented from one of three distances (1, 2, or 6 m) to observers who had either minimal room information or an exposure which included talking within the room. Perceived distance varied significantly with physical distance regardless to exposure condition.     

Visual perceptual abilities of Chinese-speaking and English-speaking children

This paper reports an investigation of Chinese-speaking and English-speaking children's general visual perceptual abilities. The Developmental Test of Visual Perception was administered to 41 native Chinese-speaking children of mean age 5 yr. 4 mo. in Hong Kong and 35 English-speaking children of mean age 5 yr. 2 mo. in Melbourne. Of interest were the two interrelated components of visual perceptual abilities, namely, motor-reduced visual perceptual and visual-motor integration perceptual abilities, which require either verbal or motoric responses in completing visual tasks. Chinese-speaking children significantly outperformed the English-speaking children on general visual perceptual abilities. When comparing the results of each of the two different components, the Chinese-speaking students' performance on visual-motor integration was far better than that of their counterparts (ES = 2.70), while the two groups of students performed similarly on motor-reduced visual perceptual abilities. Cultural factors such as written language format may be contributing to the enhanced performance of Chinese-speaking children's visual-motor integration abilities, but there may be validity questions in the Chinese version.     

The relative sensitivities of same-different and identification judgment models to perceptual dependence

Probabilistic models of same-different and identification judgments are compared (within each paradigm) with regard to their sensitivity to perceptual dependence or the degree to which the underlying psychological dimensions are correlated. Three same-different judgment models are compared. One is a step function or decision bound model and the other two are probabilistic variants of a similarity model proposed by Shepard. Three types of identification models are compared: decision bound models, a probabilistic multidimensional scaling model, and probabilistic models based on the Shepard-Luce choice rule. The decision bound models were found to be most sensitive to perceptual dependence, especially when there is considerable distributional overlap. The same-different model based on the city-block metric and an exponential decay similarity function, and the corresponding identification model were found to be particularly insensitive to perceptual dependence. These results suggest that if a Shepard-type similarity function accurately describes behavior, then under typical experimental conditions it should be difficult to see the effects of perceptual dependence. This result provides strong support for a perceptualindependence assumption when using these models. These theoretical results may also play an important role in studying different decision rules employed at different stages of identification training.We thank Robert Melara, Jerome Busemeyer and three anonymous reviewers for comments on an earlier draft of this paper.     

Visual-touch perceptual equivalence for shape information in children and adults

Although there has been substantial developmental research which has compared shape information processing performance under visual and touch conditions, there has been little work that bears on the shape attributes that are routinely employed, or on the similarity between shape attributes employed by adults and those employed by children. The present research was carried out to investigate the visual-touch perceptual equivalence of young children, using multidimensional scaling techniques, and to compare the visual and touch perceptual structures of this age group with those of adults. The results provide evidence for adult-like perceptions of shape among 6-year-olds, in terms of both the patterns of interstimulus similarities and the shape attributes attended to by children using each modality. In addition, it was found that children have somewhat more visual-touch perceptual equivalence than adults do.     

Collaboration in young children

Humans accomplish much of what they do in collaboration with others. In ontogeny, children's earliest abilities to collaborate develop in two basic steps. First, 1- and 2-year-olds learn to form with others joint goals and joint attention--which include an understanding of the individual roles and perspectives involved. Second, as they approach their third birthdays, children's collaborative interactions with others take on a more normative dimension involving obligations to the partner. In addition, their cognitive abilities to conceptualize simultaneously both their own role and perspective along with those of the other develop considerably as well. This form of collaborative interaction is underlain by species-unique skills and motivations for shared intentionality that make possible, ultimately, such things as complex cultural institutions.