Modulation of the perception of temporal order by attentional and pre-attentional factors

When two stimuli are presented simultaneously to an observer, the perceived temporal order does not always correspond to the actual one. In three experiments we examined how the location and spatial predictability of visual stimuli modulate the perception of temporal order. Thirty-two participants had to report the temporal order of appearance of two visual stimuli. In Experiment 1, both stimuli were presented at the same eccentricity and no perceptual asynchrony between them was found. In Experiment 2, one stimulus was presented close to the fixation point and the other, peripheral, stimulus was presented in separate blocks in two eccentricities (4.8º and 9.6º). We found that the peripheral stimulus was perceived to be delayed in relation to the central one, with no significant difference between the delays obtained in the two eccentricities. In Experiment 3, using three eccentricities (2.5º, 7.3º and 12.1º) for the presentation of the peripheral stimulus, we compared a condition in which its location was highly predictable with two other conditions in which its location was progressively less predictable. Here, the perception of the peripheral stimulus was also delayed in relation to the central one, with this delay depending on both the eccentricity and predictability of the stimulus. We argue that attentional deployment, manipulated by the spatial predictability of the stimulus, seems to play an important role in the temporal order perception of visual stimuli. Yet, under whichever condition of spatial predictability, basic sensory and attentional processes are unavoidably entangled and both factors must concur to the perception of temporal order.

Vision, image, record : a cultivation of the visual field

I den första delen av den här avhandlingen presenteras en bildens genealogi. Den skildrar hur begreppen för bilden, seendet och jaget utvecklades i relation till varandra i en specifik vetenskaplig och filosofisk kontext. Berättelsen sträcker sig från den tidiga renässansen och det perspektivistiska måleriet, till fotografiets födelse och positivismen. Den här utvecklingen medförde en form av reduktionism i vilken jagets roll – betydelsen av den mänskliga psykologin, vårt omdöme, vår uppmärksamhet och vår vilja – blev förbisedd. Inom den här tanketraditionen uppstod en förskjutning, från en förståelse av bilden som en representation av det tredimensionella rummet på en tvådimensionell yta, till en uppfattning om bilden som en genomskinlig ruta, ett fönster ut mot världen. Idén om avbildningen som en neutral ”blick från ingenstans” kom att förstärka en skeptisk hållning till kommunikation, dialog och vittnesmål och därmed även undergräva vår tillit till varandra och följaktligen vår tillit till oss själva. I den andra delen erbjuder författaren ett alternativ till den tanketradition som behandlas i den första delen. Det som blev förbisett i uppfattningen om en blick från ingenstans var att bilden är ett hjälpmedel då vi bearbetar vårt synfält. Bilden hjälper oss att dela vår syn på saker. Genom den här uppgiften av att dela blir bilden riktningsgivande i våra försök att orientera oss i världen. Jag kan stå bredvid en annan människa och se vad hon ser, men jag vet inte nödvändigtvis hur hon uppfattar det vi ser. Bilden lägger till ett led i det här förhållandet eftersom den inte enbart visar vad den andra ser. När bilden fungerar som den skall visar den också hur den andra ser och på det här sättet blir bilden verksam. Den föreliggande avhandlingen kombinerar epistemologi med vetenskapshistoria och visuella kulturstudier, men dess huvudintresse är filosofiskt. Den befattar sig med filosofiska missförstånd angående avbildning som en mimetisk konstform, kunskap som domesticering och varseblivning som mottagning av data. ------------------------------------------------------ Tämän väitöskirjan ensimmäinen osa selvittää kuvakäsitteen genealogiaa. Se havainnollistaa miten kuvan, näkemisen ja minän käsitteet kehittyivät suhteessa toisiinsa. Kertomus ulottuu varhaisesta renessanssista ja perspektivistisestä maalaustaiteesta, positivismin aikakauteen ja valokuvan syntyyn. Tämä kehitys toi mukanaan reduktionismin jossa minän rooli – ihmisen psykologian merkitys, meidän arviointikyky, meidän huomiokyky sekä meidän tahtomme – vaipui unohduksiin. Ajatusmaailmassa tapahtui siirtymä, kuvan merkitys vaihtui käsityksestä jossa se on kolmiulotteisen tilan representaatio kaksiulotteisella pinnalla, käsitykseen jossa kuva on läpinäkyvä ruutu, ikkuna kohti maailmaa. Ajatus kuvasta neutraalin näkökulman kantajana vahvisti skeptistä suhtautumista kommunikaatiota, dialogisuutta ja subjektiivisuutta kohtaan. Tämä skeptisyys ilmentyi myös vahvana epäluottamuksena ihmiskeskeisyyttä ja toiseutta kohtaan. Toisessa osassa tekijä tarjoaa vaihtoehdon tälle skeptiselle ajatusmaailmalle jota tarkastellaan ensimmäisessä osassa. Kuva on myös väline joka auttaa meitä jäsentämään meidän näkökenttäämme. Se auttaa meitä jakamaan meidän käsityksiä toistemme kanssa. Tämä näkemisen jakamisen käytäntö on kuvan keskeinen tehtävä. Voin seistä toisen ihmisen vieressä ja nähdä samat asiat kuin hän, mutta en välttämättä ymmärrä miten hän näkee nämä asiat. Kuva lisää jotain olennaista tähän suhteeseen. Kun kuva toimii niin kun sen kuuluu toimia, se näyttää myös miten toinen näkee, tällä tavalla kuvasta tulee välittäjä. Tämä väitöskirja yhdistää epistemologiaa, tieteen historiaa ja visuaalisen kulttuurin tutkimusta, mutta sen pääasiallinen tavoite on filosofinen. Se käsittelee filosofisia väärinkäsityksiä koskien kuvan eideettisyyttä.

Interhemispheric connections between primary visual areas: beyond the midline rule

In the last five years, a number of detailed anatomical, electrophysiological, optical imaging and simulation studies performed in a variety of non-human species have revealed that the functional organization of callosal connections between primary visual areas is more elaborate than previously thought. Callosal cell bodies and terminals are clustered in columns whose correspondence to features mapped in the visual cortex, such as orientation and ocularity, are starting to be understood. Callosal connections are not restricted to the vertical midline representation nor do they establish merely point-to-point retinotopic correspondences across the hemispheres, as traditionally believed. In addition, anatomical studies have revealed the existence of an ipsilateral component of callosal axons. The aim of this short review is to propose how these new data can be integrated into an updated scheme of the circuits responsible for assembling the primary visual field map.

Visual maps in the adult primate cerebral cortex: some implications for brain development and evolution

In this paper, the topology of cortical visuotopic maps in adult primates is reviewed, with emphasis on recent studies. The observed visuotopic organisation can be summarised with reference to two basic rules. First, adjacent radial columns in the cortex represent partially overlapping regions of the visual field, irrespective of whether these columns are part of the same or different cortical areas. This primary rule is seldom, if ever, violated. Second, adjacent regions of the visual field tend to be represented in adjacent radial columns of a same area. This rule is not as rigid as the first, as many cortical areas form discontinuous, second-order representations of the visual field. A developmental model based on these physiological observations, and on comparative studies of cortical organisation, is then proposed, in order to explain how a combination of molecular specification steps and activity-driven processes can generate the variety of visuotopic organisations observed in adult cortex.

Priming effects of a peripheral visual stimulus in simple and go/no-go tasks

The early facilitatory effect of a peripheral spatially visual prime stimulus described in the literature for simple reaction time tasks has been usually smaller than that described for complex (go/no-go, choice) reaction time tasks. In the present study we investigated the reason for this difference. In a first and a second experiment we tested the participants in both a simple task and a go/no-go task, half of them beginning with one of these tasks and half with the other one. We observed that the prime stimulus had an early effect, inhibitory for the simple task and facilitatory for the go/no-go task, when the task was performed first. No early effect appeared when the task was performed second. In a third and a fourth experiment the participants were, respectively, tested in the simple task and in the go/no-go task for four sessions (the prime stimulus was presented in the second, third and fourth sessions). The early effects of the prime stimulus did not change across the sessions, suggesting that a habituatory process was not the cause for the disappearance of these effects in the first two experiments. Our findings are compatible with the idea that different attentional strategies are adopted in simple and complex reaction time tasks. In the former tasks the gain of automatic attention mechanisms may be adjusted to a low level and in the latter tasks, to a high level. The attentional influence of the prime stimulus may be antagonized by another influence, possibly a masking one.

The modulation of simple reaction time by the spatial probability of a visual stimulus

Simple reaction time (SRT) in response to visual stimuli can be influenced by many stimulus features. The speed and accuracy with which observers respond to a visual stimulus may be improved by prior knowledge about the stimulus location, which can be obtained by manipulating the spatial probability of the stimulus. However, when higher spatial probability is achieved by holding constant the stimulus location throughout successive trials, the resulting improvement in performance can also be due to local sensory facilitation caused by the recurrent spatial location of a visual target (position priming). The main objective of the present investigation was to quantitatively evaluate the modulation of SRT by the spatial probability structure of a visual stimulus. In two experiments the volunteers had to respond as quickly as possible to the visual target presented on a computer screen by pressing an optic key with the index finger of the dominant hand. Experiment 1 (N = 14) investigated how SRT changed as a function of both the different levels of spatial probability and the subject's explicit knowledge about the precise probability structure of visual stimulation. We found a gradual decrease in SRT with increasing spatial probability of a visual target regardless of the observer's previous knowledge concerning the spatial probability of the stimulus. Error rates, below 2%, were independent of the spatial probability structure of the visual stimulus, suggesting the absence of a speed-accuracy trade-off. Experiment 2 (N = 12) examined whether changes in SRT in response to a spatially recurrent visual target might be accounted for simply by sensory and temporally local facilitation. The findings indicated that the decrease in SRT brought about by a spatially recurrent target was associated with its spatial predictability, and could not be accounted for solely in terms of sensory priming.

Behavioral modulation by mutilation pictures in women

Previous studies have shown that women are more emotionally expressive than men. It is unclear, however, if women are also more susceptible to the emotional modulation of behavior imposed by an affective stimulus. To investigate this issue, we devised a task in which female subjects performed six sequential trials of visual target detection following the presentation of emotional (mutilation and erotic) or neutral pictures (domestic utensils and objects) and compared the data obtained in the present study with those described in a previous study with male subjects. The experiment consisted of three blocks of 24 pictures and each block had an approximate duration of 4 min. Our sample consisted of 36 subjects (age range: 18 to 26 years) and each subject performed all blocks. Trials following the presentation of mutilation pictures (283 ms) had significantly slower reaction times than those following neutral (270 ms) pictures. None of the trials in the "pleasant block" (271 ms) was significantly different from those in the "neutral block". The increase in reaction time observed in the unpleasant block may be related in part to the activation of motivational systems leading to an avoidance behavior. The interference effect observed in this study was similar to the pattern previously described for men. Thus, although women may be more emotionally expressive, they were not more reactive to aversive stimuli than men, as measured by emotional interference in a simple reaction time task.

Inhibition of return, gap effect and saccadic reaction time to a visual target

Simple manual reaction time (MRT) to a visual target (S2) is shortened when a non-informative cue (S1) is flashed at the S2 location shortly before the onset of S2 (early facilitation). Afterwards, MRT to S2 appearing at the S1 location is lengthened (inhibition of return - IOR). Similar results have been obtained for saccadic reaction time (SRT). Moreover, when there is a temporal gap between offset of the fixation point (FP) and onset of a target (gap paradigm), SRT is shorter than SRT in an overlap paradigm (FP remains on). In the present study, we determined SRT to S2 (10º) after presenting S1 at the same eccentricity (10º) or at a parafoveal position (2º) in the same or in the opposite hemifield. In addition, we employed both gap and overlap paradigms. Twelve subjects were asked not to respond to S1 (2º or 10º) to the right or to the left of FP, but to respond by making a saccadic movement in response to S2. We obtained the following results: 1) a 40-ms gap effect, 2) an interaction between gap effect and IOR, 3) a 39-ms delay (IOR) when S2 appeared at the cued (S1) position, and 4) a smaller (17 ms) but significant inhibition when S1 occurred at 2º in the ipsilateral hemifield. Thus, a parafoveal (2º) S1 elicits an inhibition of SRT towards ipsilateral peripheral targets. Since an inhibition of the ipsilateral hemifield by a 1º eccentric cue has been reported to occur when manual responses are employed, we suggest that the postulated functional link between covert and overt orienting of attention is also valid for parafoveal cues.

Contrast sensitivity threshold measured by sweep-visual evoked potential in term and preterm infants at 3 and 10 months of age

Although healthy preterm infants frequently seem to be more attentive to visual stimuli and to fix on them longer than full-term infants, no difference in visual acuity has been reported compared to term infants. We evaluated the contrast sensitivity (CS) function of term (N = 5) and healthy preterm (N = 11) infants at 3 and 10 months of life using sweep-visual evoked potentials. Two spatial frequencies were studied: low (0.2 cycles per degrees, cpd) and medium (4.0 cpd). The mean contrast sensitivity (expressed in percentage of contrast) of the preterm infants at 3 months was 55.4 for the low spatial frequency (0.2 cpd) and 43.4 for the medium spatial frequency (4.0 cpd). At 10 months the low spatial CS was 52.7 and the medium spatial CS was 9.9. The results for the term infants at 3 months were 55.1 for the low spatial frequency and 34.5 for the medium spatial frequency. At 10 months the equivalent values were 54.3 and 14.4, respectively. No difference was found using the Mann-Whitney rank sum T-test between term and preterm infants for the low frequency at 3 or 10 months or for the medium spatial frequency at 3 or 10 months. The development of CS for the medium spatial frequency was equally fast for term and preterm infants. As also observed for visual acuity, CS was equivalent among term and preterm infants, suggesting that visual experience does not modify the development of the primary visual pathway. An earlier development of synapses in higher cortical visual areas of preterm infants could explain the better use of visual information observed behaviorally in these infants.

Control of attention by a peripheral visual cue depends on whether the target is difficult to discriminate

The influence of a peripheral cue represented by a gray ring on responsivity to a subsequent target varies. When a vertical line inside a ring was a go target and a white small ring inside a ring was a no-go target, reaction time was shorter at the same location relative to a different location. However, no reaction time difference between the two locations occurred when a white cross inside the ring, instead of the white vertical line inside the ring, was the go target. We investigated whether this last finding was due to a forward masking influence of the cue, a requirement of low attention for the discrimination or a lack of attention mobilization by the cue. In Experiment 1, the intensity of the cue was reduced in an attempt to reduce forward masking. In Experiment 2, the vertical line and the cross were presented in the same block of trials so as to be dealt with a common attentional strategy. In Experiments 3 and 4, the no-go target was a 45º rotated cross inside a ring to increase the difficulty of the discrimination. No evidence was obtained that the cross was forward masked by the cue nor that it demanded less attention to be discriminated from the small ring. There was a facilitation of responsivity by the cue when the small ring was replaced by the rotated cross. The results suggest that when the discrimination to be performed is too easy the cue does not mobilize attention.

Visual analytics for behavioral and niche market segmentation

Companies require information in order to gain an improved understanding of their customers. Data concerning customers, their interests and behavior are collected through different loyalty programs. The amount of data stored in company data bases has increased exponentially over the years and become difficult to handle. This research area is the subject of much current interest, not only in academia but also in practice, as is shown by several magazines and blogs that are covering topics on how to get to know your customers, Big Data, information visualization, and data warehousing. In this Ph.D. thesis, the Self-Organizing Map and two extensions of it – the Weighted Self-Organizing Map (WSOM) and the Self-Organizing Time Map (SOTM) – are used as data mining methods for extracting information from large amounts of customer data. The thesis focuses on how data mining methods can be used to model and analyze customer data in order to gain an overview of the customer base, as well as, for analyzing niche-markets. The thesis uses real world customer data to create models for customer profiling. Evaluation of the built models is performed by CRM experts from the retailing industry. The experts considered the information gained with help of the models to be valuable and useful for decision making and for making strategic planning for the future.

The importance of package design to Japanese consumers: The role of visual and informational elements of package design in decision making

The importance of package design as a marketing tool is growing as the competition in retail environment increases. However, there is a lack of studies on how each element of package design affects consumer decisions in different countries. The objective of this thesis is to study the role of package design to Japanese consumers. The research was conducted through an experiment with a sample of 37 Japanese female participants. They were divided into two groups and were given different tasks: one group had to choose a chocolate for themselves, and the other for a group of friends. The participants were presented with 15 different Finnish chocolate boxes to choose from. The qualitative data was gathered through observation and semi-structured interviews. In addition, data from questionnaires was quantified and all the data was triangulated. The empirical results suggest that visual elements strongly affect the decision making of Japanese consumers. Image was the most important element which acted as both, a visual and an informational aspect in the experiment. Informational elements on the other hand have little effect, especially when the context is written in a foreign language. However, informational elements affected participants who were choosing chocolates for a group of friends. A unique finding was the importance of kawaii (cuteness) to Japanese consumers.

Comparison of anaerobic threshold determined by visual and mathematical methods in healthy women

Several methods are used to estimate anaerobic threshold (AT) during exercise. The aim of the present study was to compare AT obtained by a graphic visual method for the estimate of ventilatory and metabolic variables (gold standard), to a bi-segmental linear regression mathematical model of Hinkley's algorithm applied to heart rate (HR) and carbon dioxide output (VCO2) data. Thirteen young (24 ± 2.63 years old) and 16 postmenopausal (57 ± 4.79 years old) healthy and sedentary women were submitted to a continuous ergospirometric incremental test on an electromagnetic braking cycloergometer with 10 to 20 W/min increases until physical exhaustion. The ventilatory variables were recorded breath-to-breath and HR was obtained beat-to-beat over real time. Data were analyzed by the nonparametric Friedman test and Spearman correlation test with the level of significance set at 5%. Power output (W), HR (bpm), oxygen uptake (VO2; mL kg-1 min-1), VO2 (mL/min), VCO2 (mL/min), and minute ventilation (VE; L/min) data observed at the AT level were similar for both methods and groups studied (P > 0.05). The VO2 (mL kg-1 min-1) data showed significant correlation (P < 0.05) between the gold standard method and the mathematical model when applied to HR (r s = 0.75) and VCO2 (r s = 0.78) data for the subjects as a whole (N = 29). The proposed mathematical method for the detection of changes in response patterns of VCO2 and HR was adequate and promising for AT detection in young and middle-aged women, representing a semi-automatic, non-invasive and objective AT measurement.

Analysis of the diagnostic presentation profile, parathyroidectomy indication and bone mineral density follow-up of Brazilian patients with primary hyperparathyroidism

Primary hyperparathyroidism is an endocrine disorder with variable clinical expression, frequently presenting as asymptomatic hypercalcemia in Western countries but still predominantly as a symptomatic disease in developing countries. The objective of this retrospective study was to describe the diagnostic presentation profile, parathyroidectomy indication and post-surgical bone mineral density follow-up of patients with primary hyperparathyroidism seen at a university hospital. We found 115 patients (92 women, median age 56 years) with primary hyperparathyroidism diagnosed during the last 20 years. We defined symptomatic patients based on the presence of any classical symptom affecting bone, kidney or the neuromuscular system. Surgical criteria followed the guidelines of the National Institutes of Health regarding asymptomatic primary hyperparathyroidism. Symptomatic patients and patients meeting surgical criteria for parathyroidectomy were 66 and 93% of the sample, respectively. Median calcium and parathyroid hormone values were 11.9 mg/dL and 189 pg/mL, respectively. After surgical treatment, 97% of patients were cured, with increases in bone mineral density of 19.4% in the lumbar spine and 15.7% in the femoral neck 3 years after surgery. Greater bone mass increases were detected in pre-menopausal women, men, and in symptomatic and younger patients, both in the lumbar spine and femoral neck. Our results support the previous findings of a predominantly symptomatic disease with a presentation profile that could be mainly related to a delayed diagnosis. Nevertheless, genetic and racial backgrounds, and nutritional factors such as calcium and vitamin D deficiency may play a role in the clinical presentation of primary hyperparathyroidism of Brazilian patients.