Does speed of recognition predict two-alternative forced-choice performance? Replicating and extending Starns, Dubé, and Frelinger (2018)

Does the speed of single-item recognition errors predict performance in subsequent two-alternative forced-choice (2AFC) trials that include an item with a previous error response? Starns, Dubé, and Frelinger found effects of this kind in two experiments and accounted for them in terms of continuous memory-strength signal guiding recognition decisions. However, the effects of error speed might just as well only reflect an artefact due to an error-correction strategy that uses response latency as a heuristic cue to guide 2AFC responses, elicited through confounding factors in their experimental design such as error-correction instructions and feedback. Using two conditions, a replication condition, replicating the procedure from Starns et al., and an extension condition (each n = 130), controlling for the named shortcomings, we replicated the error speed effect. In both conditions, speed of errors in a single-item recognition task was predictive of subsequent 2AFC performance, including the respective error item. To be more precise, fast errors were associated with decreased 2AFC performance. As there was no interaction with the factor condition, the results support the idea that speed of single-item recognition responses reflects the amount of memory information underlying the respective response rather than being used for a simple error-correction strategy to improve 2AFC performance.

Introspection during short-term memory scanning

The literature in metacognition has argued for many years that introspective access to our own mental content is restricted to the cognitive states associated with the response to a task, such as the level of confidence in a decision or the estimation of the response time; however, the cognitive processes that underlie such states were deemed inaccessible to participants’ consciousness. Here, we ask whether participants could introspectively distinguish the cognitive processes that underlie two short-term memory tasks. For this purpose, we asked participants, on a trial-by-trial basis, to report the number of items that they mentally scanned during their short-term memory retrieval, which we have named “subjective number of scanned items.” The subjective number of scanned items index was evaluated, in Experiment 1, immediately after a judgment of recency task and, in Experiment 2, after an item recognition task. Finally, in Experiment 3, both tasks were randomly mixed. The results showed that participants’ introspection successfully accessed the complexity of the decisional processes.

Human episodic memory retrieval is accompanied by a neural contiguity effect

Cognitive psychologists have long hypothesized that experiences are encoded in a temporal context that changes gradually over time. When an episodic memory is retrieved, the state of context is recovered—a jump back in time. We recorded from single units in the MTL of epilepsy patients performing an item recognition task. The population vector changed gradually over minutes during presentation of the list. When a probe from the list was remembered with high confidence, the population vector reinstated the temporal context of the original presentation of that probe during study—a neural contiguity effect that provides a possible mechanism for behavioral contiguity effects. This pattern was only observed for well-remembered probes; old probes that were not well-remembered showed an anti-contiguity effect. These results constitute the first direct evidence that recovery of an episodic memory in humans is associated with retrieval of a gradually-changing state of temporal context—a neural “jump-back-in-time” that parallels the act of remembering.Significance statementEpisodic memory is the ability to re-live a specific experience from one’s life. For decades, researchers have hypothesized that, unlike other forms of memory that can be described as simple associations between stimuli, episodic memory depends on the recovery of a neural representation of spatiotemporal context. During study of a sequence of stimuli, the brain state of epilepsy patients changed slowly over at least a minute. When the participant remembered a particular event from the list, this gradually-changing state was recovered. This provides direct confirmation of the prediction from computational models of episodic memory. The resolution of this point means that the study of episodic memory can focus on the mechanisms by which this representation of spatiotemporal context is maintained and, sometimes recovered.

Short article: Visual similarity at encoding and retrieval in an item recognition task

The aim of this experiment was to examine the effects of shape similarity in visual working memory using a six alternative recognition task of Chinese characters. Shape similarity among items was manipulated at both encoding and retrieval in order to assess in which phase similarity impairs recognition to a greater degree. Results revealed that performance is particularly facilitated by high discriminability at retrieval but also by the presence of similar items at encoding, as similarity simplifies the global representation of the display and reduces memory load. Moreover, results provide further evidence that the classical similarity effect can be reversed in the visual domain when item memory (as opposed to order) is assessed.

Methodological considerations in estimating speed of cognitive operations

Individuals infected with Human Immunodeficiency Virus (HIV) and having cognitive impairment have been described as having slow mentation. Data supporting this proposition come from a variety of sources, including Sternberg's (1966) item recognition memory task. The procedure nominally provides an index of speed of mental operations, independent from input/output demands. However, since the original use of this procedure in the 1960s, advances in cognitive psychology have revealed many of its limitations. The purpose of the present study was to examine the psychometric characteristics of this task. Each participant performed the Sternberg item recognition task twice, 6 mo apart. The stability of the estimate of the slope of regression equations and for zero intercept ranged from excellent (r = .87) to poor (r = .30), and the data from many individual subjects could not be reliably modelled using multiple linear regression techniques. These data, as well as those from previous research, demonstrate the limited practical use of this task in clinical samples. Furthermore, as cognitive psychological theory has advanced in the past 30 yr, the conceptual underpinnings of the procedure have essentially evaporated. (JINS, 1995, 1, 3–9).

Correlations among Measures of Performance on Sternberg's Item-Recognition Task

Examination of the correlations among measures of performance on Sternberg's item-recognition task by 136 students showed a low correlation of. 38 between the slopes of the functions relating response latency to set size for positive and negative responses. The correlation between the mean latency of positive and negative responses was substantially higher (r =. 91) than that of the slopes. The low correlation between the slopes suggests a mechanism such as an adjustable response criterion that results in a tradeoff between response latency on positive and negative trials.

The Temporal Dynamics of Event Memory: A Stage Analysis of Mnemonic Processing by Man and Macaque

Extensive anatomical and psychophysical data suggest that macaques can serve as surrogates for man in studies of the neural substrates of visual mnemonic processing. However, the extent to which mnemonic-mechanisms in macaques can be validly compared to those in man depends critically on the demonstration that the cognitive strategy and temporal dynamics of mnemonic retrieval are congruent For the two species. Seven human and six macaque subjects were tested on identical versions of an item recognition task that required the classification of probe stimuli as positive or negative according to whether or not they were members of a previously defined set of target stimuli. For the human subjects, reaction time increased by an average of 24 msec/target. The macaques were able to respond as accurately as the human subjects, but each additional target resulted in a reaction time increment of only 7 msec. A detailed analysis of the statistical properties of the reaction-time distributions indicated that these data do not reflect a between-species difference in the efficiency of execution of otherwise comparable, serial-exhaustive, retrieval mechanisms. Rather, the data suggest that human subjects engage two memory-load dependent processes before generating a response, while macaques execute only one of these. Additional data indicate that a reaction-time approach toward the analysis of the stages of mnemonic processing can provide new insights into the specific nature of mnemonic deficits induced by brain damage.