Is time to scan visual images due to demand characteristics?

The time to scan across an object in a mental image increases with the distance scanned. Does this finding reflect the operation of underlying mechanisms or the effects of demand characteristics? Two types of demand characteristics were considered here. First, the scanning effects were shown to persist even when they conflicted with the experimenters' expectations. Experimenters were led to expect different rates of scanning and different effects of distance on scan times, but the results in all cases showed no hint of experimenter effects, instead displaying the usual increase in time with distance scanned. Second, the scanning effects were shown to persist in the absence of implicit task demands. Effects of distance were observed in an experiment in which subjects were never asked to scan the image; furthermore, such effects were observed only for items that should require spontaneous scanning even though they were randomly intermixed with items that should not, and this distinction was never mentioned nor alluded to in the instructions. Thus, experimenter effects and task demands are not sufficient explanations for the increase in the time to scan across an image as distance is increased.     

Finger-pressure waveforms measured on Clynes' Sentograph distinguish among emotions

We examined the transient finger-pressure when subjects were exposed to the schematic faces which depict "anger," "joy," "sadness," and "no emotion," and to two nonfacial stimuli. In Exp. 1, nine undergraduate women were asked to discriminate between those target stimuli and the nontarget stimuli by pressing on the finger rest of Clynes' Sentograph, without informing subjects that this experiment was to measure emotions. In Exp. 2, the same subjects were asked to express their feelings evoked by the schematic faces by pressing on the finger rest. Results indicate that, even on the discrimination task, the differentiation in the finger-pressure waveforms among emotions was observed. Such differentiation suggests the possibility of measuring the expression of emotions with finger pressure even when the subjects are not aware their emotions are being measured. The identifiable characteristics of the waveforms are the long duration for "sadness" and the strong intensity of pressure for "anger."     

Mental extrapolation in patterns constructed from memory

Finke and Pinker (1982, 1983) showed subjects an array of dots followed by an arrow in a blank field, and asked them to determine whether the arrow pointed to any of the previously seen dots. Response times were linearly related to the distance between the arrow and the nearest dot, suggesting that subjects spontaneously used an internal scanning or extrapolation process to perform the task. We replicate and extend this finding by varying the retention interval, and by employing a paradigm in which subjects’ eyes are closed and the arrows are described to them using a coordinate scheme. We also show that subjects are unable to predict the form of the data when the task simply is described to them. Results suggest that mental scanning along a straight path can be performed on images reconstructed from memory, and that it does not depend on the ongoing perception of a continuous surface, on physical eye movements, or on demand characteristics.     

Reaction Time of Healthy Older Adults Is Reduced While Walking Fast

Attentional requirements of walking at various speeds in older adults were examined. Twenty healthy older adults (69.9?±?2.77?years; 8 males) were asked to walk a distance of 10?m at a self-selected speed as well as 30% quicker and 30% slower. Concurrently, reaction time (RT) was evaluated by having participants respond as fast as possible to randomly presented auditory stimuli. Results reveal that an accelerated walking speed generated faster RT than slow and self-selected speeds, while no difference was found between the latter. Faster RTs during an accelerated walking speed may have been precipitated by the reduced equilibrium demands of the task.     

A positional discriminability model of linear-order judgments

The process of judging the relative order of stimuli in a visual array was investigated in three experiments. In the basic paradigm, a linear array of six colored lines was presented briefly, and subject decided which of two target lines was the leftmost or rightmost (Experiment 1). The target lines appeared in all possible combinations of serial positions and reaction time (RT) was measured. Distance and semantic congruity effects were obtained, as well as a bowed serial position function. The RT pattern resembled that observed in comparable studies with memorized linear orderings. The serial position function was flattened when the background lines were homogeneously dissimilar to the target lines (Experiment 2). Both a distance effect and bowed serial position functions were obtained when subjects judged which of two target lines was below a black bar cue (Experiment 3). The results favored and analog positional discriminability model over a serial ends-inward scanning model. The positional discriminability model was proposed as a "core model" for the processes involved in judging relative order or magnitude in the domains of memory and perception.     

Two types of phenomenal instructions for size and distance judgments of objects presented on a two-dimensional plane

Demand characteristics were studied in a simple situation in which observers made size and distance estimates of stimuli presented on a two-dimensional linear perspective drawing. Half the Ss were asked questions stressing phenomenal report: The other half were asked the same questions preceded by instructions stressing the objective nature of the stimulus configuration but requesting, nonetheless, phenomenal report. Instructions resulted in a significantly greater perspective size illusion but did not affect the distance estimates. No meaningful correlations between size and distance estimates were found.     

Knowledge of spatial relations: Varying the precision with which locations must be specified

In previous studies, subjects have been asked whether one named town is north (say) of another. The results have shown that as the distance between the towns increases, reaction times decrease. Explanations have focused on a subject's disposition to derive an answer by using less precise information about location when the towns are far apart. In the present experiments, subjects who had memorized a map of Europe were asked whether an imaginary line connecting two named towns passes through a named country. The country was either large or small in area, and the distance between the towns was either long or short. It was expected that in the large country condition less precise information would be used when the distance was long than when it was short, as inferred in previous experiments. Accordingly, reaction times decreased as the distance increased. In the small country condition it was supposed that some degree of precision would be required to determine that the line ran through the country, regardless of the distance between the towns. Therefore, it was expected that the size of the country would limit the degree to which a decrease in precision could occur with an increase in distance. Consistent with this expectation, distance and size of country interacted, such that when the country was small an increase in distance did not cause a decrease in reaction time. Similar results were found in a second experiment.     

Semantic categorization in a linear order problem

The present investigation was conducted to determine whether subjects could use categorical codes based on semantic memory information (gender of names) to make rapid decisions about the order of names in a linear series. Subjects were taught linear order problems in which 12 names (six male and six female) were either randomly ordered or blocked by sex. The results support a dual-process model which proposes that subjects use both categorical information (discrete linguistic codes) and serial position information when asked to make mental comparisons of arbitrarily ordered items. Furthermore, the data indicate that both the ordinal distance between the terms in the test pair (step size) and the serial position of the test terms in the linear order affect the reaction time to a particular test comparison.     

Size-distance paradox with accommodative micropsia

Two experiments tested the hypothesis that the paradoxical relative distance judgment associated with the size-distance paradox is due to the visual system’s assuming equal linear size and perceiving a smaller angular size for the closer stimulus equal in visual angle. In Experiment I, two different sized coins were presented successively, and 16 Ss were asked to give ordinal judgments of apparent distance and apparent size. When the two coins depicted the same figures, the closer stimulus was judged to be farther and smaller, more frequently, than when two coins depicted different figures. In Experiment II, 48 Ss were asked to give ratio judgments of apparent distance, apparent linear size, and apparent angular size for two stimuli which were presented successively. When the stimuli were of equal shape, the mean ratios of the far stimulus to the near stimulus were smaller for the apparent distance but larger for the apparent linear size and angular size than when the stimuli were of different shape. The obtained distance judgments were consistent with the hypothesis but the obtained judgments of linear size and angular size were not.     

Visual images preserve metric spatial information: evidence from studies of image scanning

Four experiments demonstrated that more time is required to scan further distances across visual images, even when the same amount of material falls between the initial focus point and the target. Not only did times systematically increase with distance but subjectively larger images required more time to scan than did subjectively smaller ones. Finally, when subjects were not asked to base all judgments on examination of their images, the distance between an initial focus point and a target did not affect reaction times.     

Mental imagery and the third dimension

What sort of medium underlies imagery for three-dimensional scenes? In the present investigation, the time subjects took to scan between objects in a mental image was used to infer the sorts of geometric information that images preserve. Subjects studied an open box in which five objects were suspended, and learned to imagine this display with their eyes closed. In the first experiment, subjects scanned by tracking an imaginary point moving in a straight line between the imagined objects. Scanning times increased linearly with increasing distance between objects in three dimensions. Therefore metric 3-D information must be preserved in images, and images cannot simply be 2-D "snapshots." In a second experiment, subjects scanned across the image by "sighting" objects through an imaginary rifle sight. Here scanning times were found to increase linearly with the two-dimensional separations between objects as they appeared from the original viewing angle. Therefore metric 2-D distance information in the original perspective view must be preserved in images, and images cannot simply be 3-D "scale-models" that are assessed from any and all directions at once. In a third experiment, subjects mentally rotated the display 90 degrees and scanned between objects as they appeared in this new perspective view by tracking an imaginary rifle signt, as before. Scanning times increased linearly with the two-dimensional separations between objects as they would appear from the new relative viewing perspective. Therefore images can display metric 2-D distance information in a perspective view never actually experiences, so mental images cannot simply be "snapshot plus scale model" pairs. These results can be explained by a model in which the three-dimensional structure of objects is encoded in long-term memory in 3-D object-centered coordinate systems. When these objects are imagined, this information is then mapped onto a single 2-D "surface display" in which the perspective properties specific to a given viewing angle can be depicted. In a set of perceptual control experiments, subjects scanned a visible display by (a) simply moving their eyes from one object to another, (b) sweeping an imaginary rifle sight over the display, or (c) tracking an imaginary point moving from one object to another. Eye-movement times varied linearly with 2-D interobject distance, as did time to scan with an imaginary rifle sight; time to tract a point varied independently with the 3-D and 2-D interobject distances. These results are compared with the analogous image scanning results to argue that imagery and perception share some representational structures but that mental image scanning is a process distinct from eye movements or eye-movement commands.     

Attention and the processing of emotional words and names: not so special after all

Abstract— Previous research has suggested that a person's own name or emotionally charged stimuli automatically "grab" attention, potentially challenging limited-capacity theories of perceptual processing. In this study, subjects were shown two digits surrounding a word and asked to make a speeded judgment about whether the parity of the two digits matched. When the subject's own name was presented on a few scattered trials, responses were markedly slowed (replicating a previous study). However, in a subsequent block of trials in which half the words were the subject's name, the slowing did not occur. The same slowing occurred (but even more fleetingly) when an emotionally charged word was presented between the digits. When the name was embedded among multiple distractor words, it ceased to slow reaction times. The results suggest that perceptual analysis of high-priority stimuli is subject to the usual capacity limitations of other stimuli, but when enough capacity is available for a high-priority stimulus to be perceived, a transient surprise reaction may interrupt ongoing processing.     

Processing steps in perception of speech sounds]

The aim of this study is to investigate whether speech sounds--as is stated by the widely accepted theory of categorical perception of speech--can be perceived only as instances of phonetic categories, or whether physical differences between speech sounds lead to perceptual differences regardless of their phonetic categorization. Subjects listened to pairs of synthetically generated speech sounds that correspond to realizations of the syllables "ba" and "pa" in natural German, and they were instructed to decide as fast as possible whether they perceived them as belonging to the same or to different phonetic categories. For 'same'-responses reaction times become longer when the physical distance between the speech sounds is increased; for 'different'-responses reaction times become shorter with growing physical distance between the stimuli. The results show that subjects can judge speech sounds on the basis of perceptual continua, which is inconsistent with the theory of categorical perception. A mathematical model is presented that attempts to explain the results by postulating two interacting stages of processing, a psychoacoustical and a phonetic one. The model is not entirely confirmed by the data, but it seems to deserve further consideration.     

Visual laterality effects: A signal detection analysis

Subjects were asked to indicate, by a simple motor response, the presence or absence of a pre-designated target letter in unilaterally presented consonant trigrams. For horizontally oriented stimuli (Experiment 1), perceptual sensitivity was greater in the right visual hemifield. For vertically oriented stimuli (Experiment 2), perceptual sensitivity did not differ between visual hemifields. Decision making was less conservative and reaction time was shorter with right hemifield presentation, regardless of stimulus orientation. Practice effects and serial position curves were examined. Implications of these results attribute laterality effects to iconic scanning patterns and to postperceptual decision processes.     

Stimulus-response compatibility and sequential learning in the serial reaction time task

The serial reaction time (SRT) task is a commonly used paradigm to investigate implicit learning. In most studies the settings originally introduced by Nissen and Bullemer are replicated, i.e., subjects respond to a visuo-spatial sequence of stimulus locations by pressing spatially compatible arranged keys. The present experiment was designed to explore to what degree the sequential learning observed under these conditions depends on the use of locational sequences. Under otherwise identical conditions, first the S-R compatibility was reduced by using symbols instead of locations as stimuli, and second, the connectibility, i.e, the ease of connecting successive stimuli into coherent pattern, was varied. Effects on reaction times (RT) in the SRT task and on explicit memory in a generation task were evaluated. The results indicate that the connectibility of the stimuli has no effect at all and that S-R compatibility influences only the general RT level but does not seem to modify the learning process itself. Thus, the data are more consistent with the notion that learning is based primarily on the sequence of responses rather than on the sequence of stimuli. Moreover, a post hoc classification of subjects with regard to the amount of explicit sequence knowledge they have acquired reveals a striking modification of the general result: The RT difference between responses to locations and symbols vanishes in the course of learning for the complete explicit knowledge group. In order to account for this effect, we presume that the response control of these subjects shifts from stimuli to motor programs, so that RTs become increasingly independent of the stimuli used.     

The Red Herring technique: a methodological response to the problem of demand characteristics

In past research, we planted false memories for food related childhood events using a simple false feedback procedure. Some critics have worried that our findings may be due to demand characteristics. In the present studies, we developed a novel procedure designed to reduce the influence of demand characteristics by providing an alternate magnet for subjects' natural suspicions. We used two separate levels of deception. In addition to giving subjects a typical untrue rationale for the study (i.e., normal deceptive cover story), we built in strong indicators (the "Red Herring") that the study actually had another purpose. Later, we told subjects that we had deceived them, and asked what they believed the "real purpose" of the study was. We also interviewed a subset of subjects in depth in order to analyze their subjective experiences of the procedure and any relevant demand. Our Red Herring successfully tricked subjects, and left little worry that our false memory results were due to demand. This "double cross" technique may have widespread uses in psychological research that hopes to conceal its real hypotheses from experimental subjects.     

Differential effects of performance demand and distraction on sexually functional and dysfunctional males

Sexually functional and sexually dysfunctional male subjects viewed an erotic film while experiencing two different types of distraction. During a neutral distracting condition, subjects were asked to estimate the length and width of a straight line appearing on an adjacent video monitor. During the "performance demand" distraction condition, subjects viewed video feedback of their genital responses and were asked to estimate percentage of full erection. These conditions were compared to a no distraction control condition. Performance demand distraction significantly elevated the responding of functional subjects compared to the neutral distraction condition. The responding of dysfunctional subjects, on the other hand, decreased during the performance demand distraction and was significantly lower than arousal in functional subjects in this condition. Post hoc analyses examined possible cognitive and affective mediating factors of this differential response.     

刷微博，让焦虑的人更焦虑——特质焦虑对青少年注意情绪刺激的影响

采用自由观看眼动追踪范式,考察特质焦虑青少年在观看情绪面孔图片过程中的眼动轨迹。结果发现,高特质焦虑组对愤怒和恐惧面孔的首次注视到达时间（TFF）较快,首次注视持续时间（TFD）较短;低特质焦虑组对愤怒和恐惧面孔的TFF虽然稍早于平静面孔,但差异不显著。在刺激呈现1000ms之后,高特质焦虑组对愤怒和恐惧面孔的注视次数（FC）较多,平均注视持续时间（AFD）较短。低特质焦虑组对愤怒和恐惧面孔的FC较少,AFD较长;这就表明,高特质焦虑青少年在认知加工早期对威胁性刺激注意定向加速,没有注意解除困难,呈现“浅尝辄止”现象。而在认知加工晚期,他们则对威胁性刺激存在“反刍”现象。     

Manual reaction time to linguistic stimuli in child stutterers and nonstutterers

Ten stuttering and ten nonstuttering children, ages 4–8 yr, served as subjects for a motor reaction task to simple and complex linguistic stimuli. The subjects reacted by pressing one of four panels on a touch-sensitive board that depicted the appropriate semantic relationship in response to 30 simple and complex linguistic stimuli. There was a significant increase in the reaction time of both groups with increasing linguistic complexity. No significant differences were found in the reaction time between the two groups, nor in the interaction between group and complexity. Implications regarding linguistic processing are discussed, and an “overload” hypothesis of stuttering is dispelled. It is concluded that stutterers and nonstutterers in this study did not differ in their reaction time nor in their processing time of linguistic material.