Subitizing as pattern recognition: evidence for automaticity when non-symbolic number stimuli are canonically arranged

Subitizing allows detecting the quantity of a small set of elements (up to four) with the accuracy of counting and the velocity of estimation. Recent studies have supported a theory which considers subitizing as a visual mechanism of pattern recognition, sensitive to spatial disposition of elements. These studies have found an increase in response rate and accuracy in the assessment of quantity when elements to be enumerated are arranged in an orderly fashion. Whether the numerosity of orderly arranged elements is accessed automatically, without the requirement of attentional resources, is a relevant issue not yet empirically investigated. The current study investigated the relation between subitizing and automaticity in a target detection task where distractors were non-symbolic number stimuli (dot patterns), with two different arrangements, random or canonical (like dice faces), having the same or different numerosity in the number target. We found that with canonical patterns, in the subitizing range, response times were faster in compatible trials, and slower in incompatible trials, compared to random patterns which did not influence response times in any condition. This result revealed that when elements in a visual display form easily recognizable patterns, their numerosity is accessed automatically

Attention and Visuospatial Working Memory Share the Same Processing Resources

Attention and visuospatial working memory (VWM) share very similar characteristics; both have the same upper bound of about four items in capacity and they recruit overlapping brain regions. We examined whether both attention and VWM share the same processing resources using a novel dual-task costs approach based on a load-varying dual-task technique. With sufficiently large loads on attention and VWM, considerable interference between the two processes was observed. A further load increase on either process produced reciprocal increases in interference on both processes, indicating that attention and VWM share common resources. More critically, comparison among four experiments on the reciprocal interference effects, as measured by the dual-task costs, demonstrates no significant contribution from additional processing other than the shared processes. These results support the notion that attention and VWM share the same processing resources

Perceptual Grouping and Visual Enumeration

We used lateralized Event-Related Potential (ERP) measures – the N2pc and CDA/SPCN components – to assess the role of grouping by target similarity during enumeration. Participants saw a variable number (0, 1, 2 or 3) of same- or differently-colored targets presented among homogeneous distracters, and performed an enumeration task. Results showed that the N2pc, but not the CDA, was larger for multiple targets of identical color relative to targets of different colors. The findings are interpreted in terms of the effects of grouping on early versus late stages of multiple object processing. Within this framework, they reveal that grouping has an effect on early individuation mechanisms, while later processing mechanisms are less prone to such an influence.Psycholog

Perceptual load and enumeration: Distractor interference depends on subitizing capacity

Attention is limited, both in processing capacity (leading to phenomena of “inattentional blindness”) and in the capacity for selective focus (leading to distraction). Load theory (e.g., Lavie, 1995) accounts for both limitations by proposing that perceptual processing has limited capacity but proceeds automatically and in parallel on all stimuli within capacity. Here we tested these claims by applying load theory to the phenomenon of “subitizing”: the parallel detection and individuation of a limited number of items, established in enumeration research. We predicted that distractor interference will be found within but not beyond a person’s subitizing capacity (measured as the transition from parallel to serial slope). Participants reported the number of target shapes from brief displays while ignoring irrelevant cartoon-image distractors. As predicted, distractor cost on enumeration performance was found within subitizing capacity and eliminated in larger set sizes. Moreover, individual differences results demonstrated that distractor effects depended on an individual’s capacity (i.e., their serial-to-parallel transition point), rather than on set size per se. These results provide new evidence for the load theory hypotheses that perceptual processing is automatic and parallel within its limited capacity, while extending it to account for selective attention during enumeratio

Visual Enumeration and Estimation: Brain mechanisms, Attentional demands and Number representations.

The work presented in this thesis explored the roles of attention and number awareness in visual enumeration and estimation through a variety of methods. First, a distinction was made between different attentional modes underlying estimation and enumeration in an in-depth single case study of a patient with simultagnosia. Subsequently I demonstrated that, in visual enumeration, subitizing and counting are dissociable processes and they rely on different brain structures. This was done through a neuropsychological single case study as well as through the first large sample neuropsychological group study using a voxel-based correlation method. Following this, behavioural methods were used to examine the relations between subitizing and estimation. I found that, under conditions encouraging estimation, subitizing is an automatic process and may lead to the exact representation of small numbers, which contrasts with approximate representations for larger numerosities. Finally, a functional MRI study was conducted to highlight the brain regions that are activated for subitizable numerosities, but not for larger numerosities under distributed attention conditions. The imaging study provided converging evidence for automatic subitizing leading to an exact number representation. The last chapter discusses the implications of the contrast between subitization and counting for understanding numerical processing

Two Systems of Non-Symbolic Numerical Cognition

Studies of human adults, infants, and non-human animals demonstrate that non-symbolic numerical cognition is supported by at least two distinct cognitive systems: a “parallel individuation system” that encodes the numerical identity of individual items and an “approximate number system” that encodes the approximate numerical magnitude, or numerosity, of a set. The exact nature and role of these systems, however, have been debated for over a 100-years. Some argue that the non-symbolic representation of small numbers (<4) is carried out solely by the parallel individuation system and the non-symbolic representation of large numbers (>4) is carried out solely by the approximate number system. Others argue that all numbers are represented by the approximate number system. This debate has been fueled largely by some studies showing dissociations between small and large number processing and other studies showing similar processing of small and large numbers. Recent work has addressed this debate by showing that the two systems are present and distinct from early infancy, persist despite the acquisition of a symbolic number system, activate distinct cortical networks, and engage differentially based attentional constraints. Based on the recent discoveries, I provide a hypothesis that may explain the puzzling findings and makes testable predictions as to when each system will be engaged. In particular, when items are presented under conditions that allow selection of individuals, they will be represented as distinct mental items through parallel individuation and not as a numerical magnitude. In contrast, when items are presented outside attentional limits (e.g., too many, too close together, under high attentional load), they will be represented as a single mental numerical magnitude and not as distinct mental items. These predictions provide a basis on which researchers can further investigate the role of each system in the development of uniquely human numerical thought

Adult Female Fragile X Premutation Carriers Exhibit Age- and CGG Repeat Length-Related Impairments on an Attentionally Based Enumeration Task

The high frequency of the fragile X premutation in the general population and its emerging neurocognitive implications highlight the need to investigate the effects of the premutation on lifespan cognitive development. Until recently, cognitive function in fragile X premutation carriers (fXPCs) was presumed to be unaffected by the mutation. Although as a group fXPCs did not differ from healthy controls (HCs), we show that young adult female fXPCs show subtle age- and significant fragile X mental retardation 1 (FMR1) gene mutation-modulated cognitive function as tested by a basic numerical enumeration task. These results indicate that older women with the premutation and fXPCs with greater CGG repeat lengths were at higher risk for difficulties in the deployment of volitional attention required to count 5–8 items, but spared performance when spatial shifts of attention were minimized to subitize a few (1–3). Results from the current study add to a growing body of evidence that suggests the premutation allele is associated with a subtle phenotype and implies that the cognitive demands necessary for counting are less effectively deployed in female fXPCs compared to HCs

Diferencias en la identificación de pequeñas y grandes cantidades en base a tiempos de reacción y producción de errores: Estudio preliminar en niños de 6 y 8 años

Numerosos estudios plantean que la numeración de pequeñas y grandes cantidades recae en procesos cognitivos diferentes: la subitización de 1 a 3 objetos, entendida como la percepción inmediata y sin error de la cantidad, y el conteo secuencial, más lento y proclive a producir errores, de toda cantidad mayor a 4 (Mandler & Shebo, 1982; Dehaene, 1997; Lipton & Spelke, 2004, Piazza,Fumarola, Chinello & Melcher, 2010).Estas últimas también pueden identificarse por estimación, proceso más rápido pero menos preciso que el conteo (Dehaene,2003; Ansari, 2008). El objetivo de este trabajo fue estudiar la existencia de diferencias significativas en la numeración de pequeñas y grandes cantidades en niños de 6 y 8 años tomando en cuenta las variables velocidad y precisión al numerar. Para ello se administró a 40 niños una tarea de numeración en la que debían identificar lo más rápido posible la cantidad de puntos presentados en una pantalla. Se realizó un ANOVA de diseño mixto sobre los tiempos de reacción y la cantidad de respuestas correctas. Se hallaron diferencias significativas en los tiempos de reacción en ambas edades entre la numeración de 1 a 3 elementos y cantidades mayores, lo que condice con la existencia de procesos diferentes para la numeración de pequeñas y grandes cantidades, y permite inferir que en ambas edades los niños subitizan hasta 3 objetos. Por otro lado, se observó una interacción significativa entre la edad y la velocidad de numeración, teniendo los niños de 8 tiempos de reacción menores, lo que permite inferir que la numeración atraviesa un proceso de desarrollo.Many studies suggest that the enumeration of small and large quantities relies on different cognitive processes: the subitizing of 1-3 objects which refers to the immediate apprehension of the numerosity of a set without error, and the counting of quantities greater than 4, which is a sequential and slower process, prone to error (Mandler&Shebo, 1982; Dehaene, 1997; Lipton &Spelke, 2004; Piazza, Fumarola, Chinello& Melcher, 2010). Quantities larger than 4 can also be identified by estimation, a process faster but less precise than counting (Dehaene, 2003; Ansari, 2008).The aim of this study was to analyze the existence of significant differences in the enumeration of small and large quantities in 6 and 8-year-old children based on enumeration speed and precision. With this purpose an enumeration task was administered to 40 children who had to identify as quickly as possible the number of items present on a screen. A mixed-design analysis of variance was performed on reaction times and amount of correct answers. There were statistically significant differences in the reaction time when enumerating1- 3 elements in contrast to the enumeration of larger quantities. This is consistent with the existence of different processes underlying the enumeration of small and large quantities. According to this results 6 and 8-year-old children subitize up to three objects.Also, there was a statistically significant interaction between age and enumeration speed, where 8-year-old children had lower response times, which allows inferring that enumeration undergoes a development process during childhood.Fil: Formoso, Jesica. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de Buenos Aires. Facultad de Psicología. Instituto de Investigaciones; ArgentinaFil: Jacubovich, Silvia Patricia. Universidad de Buenos Aires. Facultad de Psicología. Instituto de Investigaciones; ArgentinaFil: Injoque Ricle, Irene. Universidad de Buenos Aires. Facultad de Psicología. Instituto de Investigaciones; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin