Differential Effects of Number of Letters on Word and Nonword Naming Latency

The issue addressed in this study is whether there are differential effects of number of letters on word and nonword naming latency. Experiment 1 examined the effect of number of letters on latency for naming high-frequency words, low-frequency words, and nonwords. Number of letters affected latency for low-frequency words and nonwords but did not affect latency for high-frequency words. Number of letters was also negatively correlated with number of orthographic neighbours, number of friends, and average grapheme frequency. Number of letters continued to affect nonword naming latency, but not low-frequency word naming latency, after the effects of orthographic neighbourhood size, number of friends, and average grapheme frequency had been accounted for. Experiment 2 found that number of letters had no effect on the latency of delayed naming of the same words and nonwords. It is concluded that the effect of number of letters on nonword naming reflects a sequential, non-lexical reading mechanism.     

Variation in working memory capacity,fluid intelligence,and episodic recall: A latent variable examination of differences in the dynamics of free recall

A latent variable analysis was conducted to examine the nature of individual differences in the dynamics of free recall and cognitive abilities. Participants performed multiple measures of free recall, working memory capacity (WMC), and fluid intelligence (gF). For each free recall task, recall accuracy, recall latency, and number of intrusion errors were determined, and latent factors were derived for each. It was found that recall accuracy was negatively related to both recall latency and number of intrusions, and recall latency and number of intrusions were positively related. Furthermore, latent WMC and gF factors were positively related to recall accuracy, but negatively related to recall latency and number of intrusions. Finally, a cluster analysis revealed that subgroups of participants with deficits in focusing the search had deficits in recovering degraded representations or deficits in monitoring the products of retrieval. The results are consistent with the idea that variation in the dynamics of free recall, WMC, and gF are primarily due to differences in search set size, but differences in recovery and monitoring are also important.     

Shifts of the psychometric function: Distinguishing bias from perceptual effects

Morgan, Dillenburger, Raphael, and Solomon have shown that observers can use different response strategies when unsure of their answer, and, thus, they can voluntarily shift the location of the psychometric function estimated with the method of single stimuli (MSS; sometimes also referred to as the single-interval, two-alternative method). They wondered whether MSS could distinguish response bias from a true perceptual effect that would also shift the location of the psychometric function. We demonstrate theoretically that the inability to distinguish response bias from perceptual effects is an inherent shortcoming of MSS, although a three-response format including also an “undecided” response option may solve the problem under restrictive assumptions whose validity cannot be tested with MSS data. We also show that a proper two-alternative forced-choice (2AFC) task with the three-response format is free of all these problems so that bias and perceptual effects can easily be separated out. The use of a three-response 2AFC format is essential to eliminate a confound (response bias) in studies of perceptual effects and, hence, to eliminate a threat to the internal validity of research in this area.     

The mental number line electrified: brain potentials in a numerical flanker task

It has been suggested that the mental representation of numbers is spatial in nature such that numbers are ordered on a mental number line. In the present investigation we use a variant of the Eriksen flanker task requiring a magnitude decision (smaller or larger than 5) for a central target number by pressing a response button with the right or left hand. The target number is flanked by irrelevant distracters that are either identical to the target, different from the target but biasing the same response, or different from the target and biasing a different response. Response latencies and event-related brain potentials were obtained in a group of healthy adults. Besides the typical response congruency effects on response latency and the N2 component of the ERP, we observed several other effects. First, numerical distance of the target to the standard 5 influenced decision latencies and amplitude and latency of the P3 component with smaller distances leading to longer decision latencies, longer P3 latencies and smaller P3 amplitudes. Second, smaller numerical distance between target and distracters led to faster decisions for response congruent and to slower decisions for response-incongruent trials. For response-incongruent trials P3 amplitude was small/large and P3 latency was long/short for small/large distances. These findings underscore the spatial character of number representation and further show that the relation between targets and distracters, although task irrelevant, is assessed automatically with facilitatory and inhibitory effects driven by spatial distance on the mental number line.     

The effects of increasing semantic-associate list length on the Deese–Roediger–McDermott false recognition memory: Dual false-memory process in retrieval from sub- and supraspan lists

In this study, the number of semantic associates in Deese–Roediger–McDermott (DRM) lists was varied from 4 to 14 in a modified Sternberg paradigm. The false alarm (FA) and correct rejection (CR) reaction time (RT)/memory-set size (MSS) functions of critical lures showed a cross-over interaction at approximately MSS 7, suggesting a reversal of the relative dominance between these two responses to the critical lure at this point and also indicating the location of the boundary between the sub- and supraspan MSS. For the subspan lists, FA to critical lures was slower than CR, suggesting a slow, strategic mechanism driving the false memory. Conversely, for the supraspan lists, critical lure FA was faster than its CR, suggesting a spontaneous mechanism driving the false memory. Results of two experiments showed that an automatic, fast, and a slow, controlled process could be error-prone or error-corrective, depending on the length of the DRM memory list. Thus there is a dual retrieval process in false memory as in true memory. The findings can be explained by both the activation/monitoring and the fuzzy-trace theories.     

Task-switching cost and repetition priming: Two overlooked confounds in the fixed-set procedure of the Sternberg paradigm and how they affect memory set-size effects

Subjects performed Sternberg-type memory recognition tasks (Sternberg paradigm) in four experiments. Category-instance names were used as learning and testing materials. Sternberg's original experiments demonstrated a linear relation between reaction time (RT) and memory-set size (MSS). A few later studies found no relation, and other studies found a nonlinear relation (logarithmic) between the two variables. These deviations were used as evidence undermining Sternberg's serial scan theory. This study identified two confounding variables in the fixed-set procedure of the paradigm (where multiple probes are presented at test for a learned memory set) that could generate a MSS RT function that was either flat or logarithmic rather than linearly increasing. These two confounding variables were task-switching cost and repetition priming. The former factor worked against smaller memory sets and in favour of larger sets whereas the latter factor worked in the opposite way. Results demonstrated that a null or a logarithmic RT-to-MSS relation could be the artefact of the combined effects of these two variables. The Sternberg paradigm has been used widely in memory research, and a thorough understanding of the subtle methodological pitfalls is crucial. It is suggested that a varied-set procedure (where only one probe is presented at test for a learned memory set) is a more contamination-free procedure for measuring the MSS effects, and that if a fixed-set procedure is used, it is worthwhile examining the RT function of the very first trials across the MSSs, which are presumably relatively free of contamination by the subsequent trials.     

Velocity-dependent EMG activity of masseter and sternocleidomastoideus muscles during a ballistic arm thrusting movement

Two experiments were conducted to investigate the functional relationship between the general somatic motor function and the oral motor function. In Experiment 1, we analyzed the relationship between the amount of masseter muscle (MSS) activity and the velocity of a ballistic, 'karate-do' arm thrusting movement (ThrMov). ThrMov velocity was measured from video images taken with a high-speed CCD camera at a frequency of 500Hz. EMGs of MSS and sternocleidomastoideus (SCM) muscles as well as other related muscles were recorded simultaneously with video images in 6 varsity 'karate-do' athletes. Pearson's correlation coefficients were calculated between EMG amplitude and movement velocity. EMG activity of MSS as well as the other muscles increased as a function of ThrMov velocity in all participants, as evidenced by highly significant (p<.01) correlation coefficients, ranging from .64 to .87 (mean: .75). MSS EMG activity attained during ThrMovs performed at maximum velocity ranged between 14.6% and 113.8% of this muscle's MVC (45.7+/-39.3% MVC, mean+/-SD). SCM was also strongly active and closely associated with MSS. Besides changes in amount of EMG activity, it was further found that R-MSS EMG onset progressively shifted to the earlier phase of the ThrMov as ThrMov velocity increased. EMG onset time of R-MSS as well as R- and L-SCMs was negatively correlated with ThrMov velocity; when performed at maximum velocity MSS activation preceded the start of ThrMov by more than 100ms, whereas MSS was recruited last at approximately 150ms after the start of ThrMov when performed at moderate speed ( approximately 50% of maximum). In Experiment 2, the effects of head movement relative to the trunk on R-MSS and SCMs EMG activity were tested in both gazing and sidelong glancing conditions. A much smaller head rotation relative to the trunk was necessary during the ThrMov in the sidelong glancing condition compared to the gazing condition. R-MSS EMG activity was affected significantly by the difference between these conditions and decreased by 5.2% MVC in the sidelong glancing condition compared to the gazing condition. In association with the change in requirement for head movement between those conditions, EMG balance between the bilateral SCMs changed substantially. Finally, marked muscle activity during ThrMov was found in the MSS that was not directly involved in performing this movement, indicating a form of 'remote facilitation'.     

Response latency and response accuracy as measures of memory

The relationship is examined between response accuracy and response latency as measures of memory, and questions are raised concerning the value of the unidimensionality assumption often invoked in theories of memory. Three paired-associate experiments investigated the effects of the length of the retention interval, the kind of processing during incidental learning, and the number of study versus test trials during intentional learning. The findings, together with a review of selected studies in the literature, support three conclusions: (1) Latency of correct recall is not necessarily more sensitive than accuracy, (2) accuracy and latency of correct recall measure different aspects of memory, and (3) latency of correct recall and latency of incorrect recall measure different aspects of memory. The available data disconfirm the idea that any unidimensional construct (such as strength or the amount of information in memory) underlies memory performance. An explanation is offered that emphasizes the distinction between encoding and retrieval processes.     

Lexical search speed in children and adults

The retrieval of words from lexical memory was investigated in kindergartners (Age 6), first-graders (Age 7), third-graders (Age 9), and adults. A lexical decision task with auditorily presented words and nonwords was used, with decision latency as the dependent variable. Multiple regression analyses were used to examine the effects of word frequency, age of word acquisition, and number of word meanings. Results showed that word frequency contributed to decision latency for all age groups, age of word acquisition contributed to all groups but the third-grade subjects, and number of word meanings did not contribute for any age group. Results are discussed in relation to a model of the lexicon in children and adults. It is suggested that factors from the external linguistic community are internalized in the lexicon at an early age.     

An analysis of latency and interresponse time in free recall

In four experiments, subjects freely recalled previously studied items while a voice key and computer recorded each item’s recall latency relative to the onset of the recall period. The measures of recall probability and mean recall latency were shown to be empirically independent, demonstrating that there exists no a priori relationship between the two. In all four experiments, latency distributions were fit well by the ex-Gaussian, suggesting that retrieval includes a brief normally distributed initiation stage followed by a longer exponentially distributed search stage. Further, the variation in mean latency stemmed from the variation in the duration of the search stage, not the initiation stage. Interresponse times (IRTs), the time elapsed between two successive item recalls, were analyzed as well. The growth of mean IRTs, plotted as a function of output position, was shown to be a simple function of the number of items not yet recalled. Finally, the mathematical nature of both free recall latency and IRT growth are shown to be consistent with a simple theoretical account of retrieval that depicts mean recall latency as a measure of the breadth of search.     

Recognition time for information stored in long-term memory

Two experiments were performed to determine the effects of number of words in a target set (varying from 10 to 26) and the nature of distractor words on the latency of both positive and negative recognition responses. Before the test phase, S memorized a list of words and then was tested with a series of single words. To each presentation S made a positive or negative response to indicate whether or not the word was a member of the memorized target list. Response latency was observed to be an increasing function of memory list length. Negative response latency also was greater if distractor words were visually or semantically similar to specific target words. The results were analyzed in terms of a modified signal detection model. It is assumed that S makes a subjective judgment of the familiarity of a test item and on that basis decides either to respond immediately or to delay the response until a search of the memorized list can be executed. Several different models of the search process are considered and evaluated against latency measures and error data.     

Latency and frequency of responding under discrete-trial fixed-interval schedules of reinforcement

Pigeons' key pecking was studied under a number of discrete-trial fixed-interval schedules of food reinforcement. Discrete trials were presented by briefly illuminating the keylight repetitively throughout the interreinforcement interval. A response latency counterpart to the fixed-interval scallop was found, latency showing a gradual, negatively accelerated decrease across the interval. This latency pattern was largely invariant across changes in fixed-interval length, number of trials per interval, and maximum trial duration. Frequency of responding during early trials in the intervals varied, however, with different schedule parameters, being directly related to fixed-interval length, inversely related to number of trials, and complexly affected by conjoint variations of fixed-interval length and number of trials. Response latency thus was found to be simply related to elapsed time during the interval while response frequency was complexly determined by other factors as well.     

A rational approach to memory search termination

An important component of many, if not all, real-world retrieval tasks is the decision to terminate memory search. Despite its importance, systematic evaluations of the potential rules for terminating search are scarce. Recent work has focused on two variables: the total time spent in memory search before search is terminated and the exit latency (the time between the last retrieved item and the time of search termination). These variables have been shown to limit the number of plausible rules for terminating memory search. Here, we introduce an alternative stopping rule based on a rational moment-to-moment cost–benefit analysis and derive a closed-form expression of the exit latency function using this rational approach. We show the model’s ability to capture critical latency data and make testable predictions about the influence of changing the relative costs and benefits of memory search. Results from an experiment are presented that support the model’s predictions. We conclude that the decision to terminate memory search is based on moment-to-moment changes in subjective utility of retrieved memories.     

Routes for Roots: A Mapping Shorthand Symbolism with Reference to Nelson Goodman’s Hidden Ars Combinatoria

A shorthand symbolism for the relational mapping of categories (MSS) is introduced and developed on the basis of Nelson Goodman's structural methodology. Through a reconstruction of extensional isomorphism that Goodman introduces as a criterion for definitional accuracy, and a brief reminder of the argument structure behind his ‘new riddle of induction’, Goodman's radical ontological relativism is turned into a protological principle of what I call ‘domain constituting philosophy’. MSS is demonstrated with reference to Goodman's symbol theory, particularly his notion of exemplification, as well as in a final structured comparison of Frege's ‘sense’ with Goodman's straightforward construction of ‘secondary extension’.     

Associative frequency and response latency

FlekkØy, K. Associative frequency and response latency. Scand. J. Psychol., 1973, 14, 199–202.MdashWith 176 Norwegian subjects in a single-word free-association experiment, latency of response was found to relate more highly to the number of different words associated with a stimulus word (D), than to the response frequency of the words involved. D is therefore assumed to reflect a basic characteristic of the associative relationship between the stimulus and response words. The inverse relationship between associative frequency and latency is interpreted to mean that frequency reflects some relatively frequent order of preference of possible response words for individual subjects.     

Stage analysis of the reaction process using brain-evoked potentials and reaction time

Summary Motor processes partly determine reaction time (RT) in both choice reaction time and in binary classification tasks. These latter tasks are popular in cognitive psychology because the experimenter believes that he has kept the motor component simple and constant and therefore can attribute changes in RT to perceptual or cognitive processes. In this paper we used the P3 component of the event-related potential (ERP) as a time marker indicating the duration of perceptual and cognitive processes. The latency of this component is believed to reflect stimulus evaluation time independent of response selection and organization time.Two types of tasks were used: a choice-reaction time task and a binary classification task. Signal similarity and S-R compatibility additively affected RT, but only signal similarity affected P3 latency. The number of items in the positive set and response type affected both P3 latency and RT. Relative response frequency changed the bias in the cognitive evaluation of the stimulus, reflected in the latency of the P3 component, and affected RT only if the subjects preset their motor system (indexed by the late CNV). A model was presented which proposes that motor processes may partially overlap with the perceptual and cognitive evaluation of the stimulus. Both ERPs and RT are necessary tools in the study of the relative timing of these processes.     

Response Complexity and the Latency of Different Movement Patterns

Two series of experiments are described in which RT of responses of varying complexity is investigated. Complexity of arm movements was manipulated in terms of (a) the amount of force exerted in resisted movements, (b) the distance moved by the limb and the direction of movement, using reversing or continuing movements, and (c) the combining of the arms in reversing and continuing movements. Simple and two-choice RT situations were used. As response complexity increased in terms of the number of sets of response units that have to be organized into a spatio-temporal sequence, the latency correspondingly increased. However latency was not affected by changes in the amount of force exerted, or in simple reversal movements. The implications of these results are discussed.     

Towards a broader scope of biomechanics in developmental studies: a commentary on Jensen (2005)

In this article, we discuss where biomechanical analysis can contribute to our understanding of motor development, and more particularly in what ways biomechanics can contribute to (1) explaining the universal sequence in motor milestones; (2) explaining variations in developmental sequence between individuals; (3) understanding the impact of context on the actions of an individual; and (4) understanding, preventing, and managing chronic disabilities. In our view, biomechanics is concerned with the dynamics of the musculo‐skeletal system (MSS) and thus provides insights in the way motion is affected by the activation of muscles and the mechanical interaction between the MSS and the environment. Biomechanical analysis is important in understanding the development of actions that depend on the perceptual‐motor loop although it cannot provide a full account of the changes in the behaviour. The contributions and limitations of specific biomechanical analyses such as the inverse and forward dynamical models are discussed in the light of the article of Jensen (2005). Copyright © 2005 John Wiley & Sons, Ltd.     

Memory comparison time for complex digit stimuli: The effect of number length

Woodworth (1938) reported that naming latency increased linearly with the number of digits per number (number length). In the present study, the Sternberg memory scanning paradigm was utilized to investigate this effect. It was found that the slope of the memory scanning function increased linearly with number length: memory scanning time was 40 msec for one-digit numbers, 70 msec for two-digit numbers and 101 msec for 3 digit numbers. The intercepts of the memory scanning functions did not differ for the three types of numbers. Thus the increase in latency may be due to the memory comparison stage of processing. The data suggest that a memory comparison operation occurs for each digit position of the complex memory items composed of more than one digit.