Prototype and exemplar accounts of category learning and attentional allocation: a reassessment

In a recent article. J. P. Minda and J. D. Smith (2002; see record 2002-00620-002) argued that an exemplar model provided worse quantitative fits than an alternative prototype model to individual subject data from the classic D. L. Medin and M. M. Schaffer (1978) 5/4 categorization paradigm. In addition, they argued that the exemplar model achieved its fits by making untenable assumptions regarding how observers distribute their attention. In this article, we demonstrate that when the models are equated in terms of their response-rule flexibility, the exemplar model provides a substantially better account of the categorization data than does a prototype or mixed model. In addition, we point to shortcomings in the attention-allocation analyses conducted by J. P. Minda and J. D. Smith (2002). When these shortcomings are corrected, we find no evidence that challenges the attention-allocation assumptions of the exemplar model.     

An attentional blink for sequentially presented targets: Evidence in favor of resource depletion accounts

Several accounts of the attentional blink (AB) have postulated that this dual-target deficit occurs because of limited-capacity attentional resources being devoted to processing the first target at the expense of the second (resource depletion accounts; e.g., Chun & Potter, 1995). Recent accounts have challenged this model (e.g., Di Lollo, Kawahara, Ghorashi, & Enns, 2005; Olivers, van der Stigchel, & Hulleman, 2007), proposing instead that the AB occurs because of subjects’ inability to maintain appropriate levels of attentional control when targets are separated by distractors. Accordingly, the AB is eliminated when three targets from the same attentional set are presented sequentially in a rapid serial visual presentation (RSVP) stream. However, under such conditions poorer identification of the first target is typically observed, hinting at a potential trade-off between the first and subsequent target performances. Consistent with this hypothesis, the present study shows that an AB is observed for successive targets from the same attentional set in an RSVP stream when the first target powerfully captures attention. These results suggest that resource depletion contributes significantly to the AB.     

Stimulus-response compatibility between stimulated eye and response location: implications for attentional accounts of the Simon effect

One influential theory of the Simon effect, the attention-shift hypothesis, states that attention movements are the origin of spatial stimulus codes. According to this hypothesis, stimulus-response compatibility effects should be absent when attention shifts are prevented. To test this prediction, we used monocular patches of color that required left or right key-press responses. About half of the subjects could discriminate which eye was stimulated (in a subsequent task), and showed strong spatial compatibility effects between the stimulated eye and the response location. The other half of the subjects could not make a utrocular discrimination (i.e., they could not judge which eye had received monocular stimulation), but the pattern of results was the same: the fastest reaction times were observed when the stimulated eye corresponded spatially to the required response (i.e., a Simon effect). Since the subjects presumably did not move their attention (from the subject's point of view, the stimuli were presented centrally), our results indicate that spatial codes can be produced in the absence of attention shifts. These results also show that utrocular discrimination can be assessed via indirect measures that are much more sensitive than explicit measures.     

Contrasting two accounts of anxiety-linked attentional bias: selective attention to varying levels of stimulus threat intensity

Previous research has established that clinical anxiety patients and nonclinical populations with high levels of anxiety vulnerability characteristically orient attention toward moderately threatening stimuli. In contrast, populations with low levels of anxiety vulnerability typically orient attention away from such stimuli. The differing experimental predictions generated by 2 classes of hypothetical explanation for this anxiety-linked attentional discrepancy were tested, using attentional probe methodology to compare the attentional responses of high and low trait anxious individuals to facial stimuli of differing threat intensities. The results support the view that all individuals orient attention away from mildly threatening stimuli and toward strongly threatening stimuli, with differences in anxiety vulnerability reflecting the intensity of stimulus threat required to elicit the attentional vigilance response.     

Adaptive preferences: merging political accounts and well-being accounts

Accounts of adaptive preferences are of two kinds: well-being accounts fully theorized for their own sake and political accounts theorized to facilitate the political project of reducing oppression and marginalization. Given their practical role, the latter are often less fully theorized, and are therefore less robust to theoretical criticism. In this paper, I first draw on well-being accounts to identify the well-theorized elements that political accounts should want to adopt in order to strengthen their project and avoid common criticisms. Second, I appeal to the political project to show the shortcomings of the well-being accounts on which I draw.     

Beyond inattentional blindness and attentional misdirection: From attentional paradigms to attentional mechanisms

Memmert (2010) tried to foster the development of attentional research by discussing four differences between attentional misdirection (AM) and inattentional blindness (IB). Considering this goal, the comment was received in the intended way by the comments of (Most, 2010) and (Moran and Brady, 2010) who make a number of highly valuable suggestions for further progress. As initially suggested by Memmert (2010) this dialog should help unravel the underlying attentional mechanisms of different paradigms. Therefore, we first discuss the suggested distinction between central and spatial IB by Most (2010). Second, we argue that working memory and perceptual load research seem particularly interesting in this regard and should be taken into consideration when conducting future research along the lines of IB and AM. Third, representative task designs can be an important mosaic piece in across-the-board attention theories and highly useful for deriving further testable hypothesis in naturalistic settings. The most important claim of all commentaries in this issue is that the proposed ideas can all be empirically tested and thereby contribute to the advancement of an unified theoretical framework incorporating IB, AM in consideration of overt and covert attention mechanisms.     

Minding the gap: spatial perseveration error in dogs

We investigated a combination of perseveration and detour behaviour in 50 domestic dogs (Canis familiaris). They were required to make a detour through a gap at one end of a straight barrier in order to reach a target. After one, two, three or four repeats, the gap was moved to the opposite end of the barrier, and the detour behaviour of the dogs was recorded. Although the dogs could solve simple detour tasks (80% correct in the first trial), they committed a perseveration error of following the previously learned route despite the clearly visible change in the location of the gap. This ‘misbehaviour’ occurred in 29 of 30 dogs after only two learning trials. They never reached a 100% correct performance level again even after four runs through the second gap location. The results suggest that dogs are reluctant to unlearn acquired spatial motor responses and reinforced navigation, which has important implications for experimental design, everyday dog training and our understanding of their mental capacities.     

Compulsive perseveration: empirical criticism on the mood-as-input model

It has been proposed that the "Mood as Input" model provides an explanation of the perseverative nature of Obsessive Compulsive (OC) behaviour (MacDonald, B. C., & Davey, G. C. L. (2005). A mood-as-input account of perseverative checking: The relationship between stop rules, mood and confidence in having checked successfully. Behaviour Research and Therapy, 43, 69-91). The model implies that task perseveration occurs when individuals (a) experience a bad mood and (b) ask themselves "did I do as much as I can?" In two earlier experiments with healthy participants (MacDonald, B. C., & Davey, G. C. L. (2005). A mood-as-input account of perseverative checking: The relationship between stop rules, mood and confidence in having checked successfully. Behaviour Research and Therapy, 43, 69-91) it was found that when the allegedly critical conditions were met (negative mood and "did I as much as I can?" stop rule) perseveration occurred on a complex text-correction task. This finding was held to support a "mood as input" explanation of compulsive perseveration. It is important to note, however, that perseveration in clinical samples occurs for very simple "tasks" (e.g. closing a door or washing ones hands) and perseveration does not increase efficacy of performance. In the present study we compared the effects of the original task to effects of text correction tasks that were simpler and more OCD-like. The original effects were replicated: the combination of negative mood and the "did I do as much as I can" stop rule provoked perseveration. Meanwhile, "perseveration" was highly functional: the more "perseveration" the more text-errors were detected. Secondly, to the degree that tasks became simpler and more OCD-like, less checking occurred and the effects of the "did I do as much as I can?" stop rule on detection of errors became smaller. The findings raise questions about the validity of the paradigm as a model of OC perseveration.     

Drawing perseveration in neglect: Effects of target density

In cancellation tasks, patients with unilateral spatial neglect typically fail to mark targets within the side of the sheet contralateral to the side of the lesion (contralesional). Moreover, they can show a perseverative behaviour, which consists in repeatedly cancelling stimuli, mainly in the side of the display ipsilateral to the side of the lesion (ipsilesional). We investigated in 13 right‐brain‐damaged patients with left spatial neglect and perseverative behaviour whether and how different densities of horizontal targets modulated omission and perseverative errors. We found that the density of targets modulated the patients’ distribution of neglect (area of omission), but not its extent, as indexed by the percentage of omissions. Specifically, the area of omissions tightened when target density increased leftwards. On the other hand, target density did not affect the distribution of perseverative behaviour (area of perseveration), as well as its extent, as indexed by the percentage of perseverations. Correlation analyses showed that both the extent and the distribution of omissions were positively correlated to clinical measures of spatial neglect. Conversely, perseverations did not show such a correlation. These findings support the view that two different pathological mechanisms might be involved in left spatial neglect and in ipsilesional perseverative behaviour.     

Children's motor imagery modality dominance modulates the role of attentional focus in motor skill learning

We investigated whether children's motor imagery dominance modulated the relationship between attentional focus and motor learning of a tossing task. One hundred and thirty-eight boys (age: M = 10.13, SD = 0.65) completed the Movement Imagery Questionnaire – Children (MIQ-C) to determine imagery modality dominance (kinesthetic, internal-visual, external-visual) and were randomly assigned to either an internal (n = 71) or external (n = 67) attentional focus group. Participants completed 60 trials of a tossing task with their non-dominant hand on day 1. Participants in the internal focus group were asked “to focus on the throwing arm”, whereas participants in the external focus group were instructed “to focus on the ball.” A retention test was conducted 24 h later to assess motor learning. Overall, the results from a nested, multiple linear regression analysis indicated the degree to which internal or external focus influences children's throwing accuracy is dependent upon their motor imagery modality dominance. Specifically, higher levels of external-visual imagery dominance resulted in greater motor learning for children adopting an external focus. In contrast, higher values of kinesthetic imagery dominance resulted in reduced motor learning for children who adopted an external focus. Despite the need for future research, we recommend motor imagery modality dominance assessments be considered when investigating the influence of attentional focus on motor learning, particularly when the target population is children.     

Attentional flexibility and perseveration: developmental aspects in young children.

Whereas a growing interest in the development of attentional flexibility (AF) and in perseverative behavior, being one marker of this component, exists in neuropsychological studies and in the domain of developmental psychopathology (e.g., PKU, infantile schizophrenia, autism and Parkinson's disease) (Pennington & Ozonoff, 1996; Stahl & Pry, 2002), only a few studies have concerned themselves with this subject in normal children. It is thus of interest to add more empirical data to the existing literature in this domain. Therefore, the aim of our study was to explore the development of AF and of perseverative errors in young preschool children with normal development, aged 1.5 to 6 years. Using set-shifting tasks of increasing difficulty level, three age groups were compared with respect to their AF skills.Results show a developmental factor underlying AF, with different levels of this form becoming more and more complex with age, ranging from a rudimentary visual form to a complex representational form of flexibility. Overall, few perseverative errors occurred and they decreased with age. Results are discussed from a developmental and neuropsychological perspective.     

Visual perseveration in normal and mentally retarded children

Visual perseveration was investigated within mentally retarded and second, fifth, and eighth grade normal children (Ns = 12 each group). Subjects matched an auditorially presented click to the onset and offset of visually presented stimuli. Time differences between visual stimulus offset and the point at which subjects reported simultaneity of the click and visual stimulus offset was assumed to reflect visual perseveration. Results showed: (a) no differences between the normal children as a function of age; (b) no difference between groups for stimuli of 100 msec. or longer duration; and (c) retarded subjects judged stimuli of 20 and 50 msec. to be of shorter duration than did normal subjects. This highly specific distinction between retarded and normal subjects suggests a difference in an early stage of perceptual processing.     

Children's original thinking: an empirical examination of alternative measures derived from divergent thinking tasks

Children's creative potential is often assessed using cognitive tests that require divergent thinking, such as the Torrance Tests of Creative Thinking (TTCT; E. P. Torrance, 1974, 1976, 1990). In this study the authors investigated the effect of various scoring systems on the originality index, evaluating the high intercorrelation of fluency and originality measures found in the TTCT scoring system and the applicability of TTCT scoring norms over time and across age groups. In 3 studies, the originality of elementary school children was measured using TTCT norms and various sample-specific scoring methods with the TTCT Unusual Uses of a Box test as well as social-problem-solving tasks. Results revealed an effect of scoring technique on creativity indices as well as on the reliability of originality scores and the relationship between originality and other ability measures. The usefulness of the various measures for understanding children's original thinking are discussed.     

No commonality between attentional capture and attentional blink

Visual search for a unique target is impaired when a salient distractor is presented (attentional capture). This phenomenon is said to occur because attention is diverted to a distractor before it reaches the target. Similarly, perception of the second of two targets embedded in a rapid stream of nontargets is impaired, suggesting attentional deprivation due to the processing of the first target (attentional blink). We examined whether these phenomena emerge from a common underlying attentional mechanism by using correlation studies. If these phenomena share a common foundation, the magnitude of these deficits should show within-subject correlations. Participants (N = 135) revealed significant attentional deficits during spatial and temporal capture and the attentional blink tasks. However, no significant correlation was found among these tasks. Experiment 2 (N = 95) replicated this finding using the same procedure as that used in Experiment 1 but included another attentional blink task that required spatial switching between the two targets. Strong correlations emerged only between the two attentional blink tasks (with/without spatial switching). The present results suggest that attentional deficits during spatial and temporal capture and the attentional blink tasks reflect different aspects of attention.     

Chain letters: Players and their accounts

Even though it is unlawful to send chain letters through the mails, thousands of Americans send them to friends, acquaintances, and strangers in hopes that their names will move to the top of the pyramid, and they will receive the influx of tax‐free dollars from those at the bottom of the chain. This paper analyzes the content and structure of the chain letter and also describes the accounts which chain letter players (N=129) provide for their participation. Differences between male and female accounts and participation strategies are provided. The implications for these differences for understanding participation in the underground economy are discussed.     

No commonality between attentional capture and attentional blink

Visual search for a unique target is impaired when a salient distractor is presented (attentional capture). This phenomenon is said to occur because attention is diverted to a distractor before it reaches the target. Similarly, perception of the second of two targets embedded in a rapid stream of nontargets is impaired, suggesting attentional deprivation due to the processing of the first target (attentional blink). We examined whether these phenomena emerge from a common underlying attentional mechanism by using correlation studies. If these phenomena share a common foundation, the magnitude of these deficits should show within-subject correlations. Participants (N?=?135) revealed significant attentional deficits during spatial and temporal capture and the attentional blink tasks. However, no significant correlation was found among these tasks. Experiment 2 (N?=?95) replicated this finding using the same procedure as that used in Experiment 1 but included another attentional blink task that required spatial switching between the two targets. Strong correlations emerged only between the two attentional blink tasks (with/without spatial switching). The present results suggest that attentional deficits during spatial and temporal capture and the attentional blink tasks reflect different aspects of attention.