,
eeg_segment()
subdivides of the EEG into different segments or epochs. (Fieldtrip calls the segment "trials".) The limits of segment
are inclusive: If, for example, lim = c(0,0)
, the segment would contain only sample 1.
An eeg_lst
object.
Description of the event.
Vector indicating the time before and after the event. Or dataframe with two columns, with nrow=total number of segments
Description of the event that indicates the end of the segment, if this is used, .lim
is ignored.
"seconds" (or "s"), "milliseconds" (or "ms"), or samples.
Initial sample when an object is unsegmented
Segment separation marker. By default: .type == "New Segment"
Time zero marker. By default: .type == "Time 0"
An eeg_lst
.
eeg_unsegment()
does not reverse the segmentation, it simply concatenates all segments creating one object with only one segment.
When there is no segmentation, the eeg_lst
contain one segment.
Other preprocessing functions:
eeg_baseline()
,
eeg_downsample()
,
eeg_ica_keep()
,
eeg_ica()
,
eeg_rereference()
,
filt
# Segments 500ms before and 1000ms after the triggers s70 and s71
data_faces_10_trials %>% eeg_segment(.description %in% c("s70", "s71"),
.lim = c(-5, 1)
)
#> # Total of 9 segments found.
#> # Object size in memory 7.3 Mb after segmentation.
#> # EEG data:
#>
#> # Signal table:
#> Key: <.id, .sample>
#> .id .sample Fp1 Fpz Fp2
#> <int> <sample_int> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: 1 -2499 -21.109169 -28.948433 -25.2941818
#> 2: 1 -2498 -26.754496 -31.574997 -29.3033142
#> 3: 1 -2497 -28.524906 -30.061056 -29.8119774
#> 4: 1 -2496 -19.430933 -21.690756 -22.9545746
#> 5: 1 -2495 -5.725405 -12.675667 -14.1778440
#> ---
#> 27005: 9 497 -8.819434 -10.321518 -4.1491461
#> 27006: 9 498 -6.959885 -10.197778 -3.9415770
#> 27007: 9 499 -1.756994 -7.125042 -1.8327932
#> 27008: 9 500 3.828817 -3.076797 0.1685476
#> 27009: 9 501 6.447233 -1.101932 0.8303175
#> F7 F3 Fz F4 F8
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: -10.91393471 -7.5658569 -8.7408314 -8.170362 -6.2060385
#> 2: -15.56297112 -8.5204601 -8.6705694 -7.897309 -6.2139606
#> 3: -18.79760742 -10.9199018 -8.0307159 -6.302173 -7.0704432
#> 4: -14.15851784 -11.1185970 -5.9641218 -3.515551 -9.4960175
#> 5: -2.97854924 -7.5502534 -3.7647977 -1.728970 -11.8486443
#> ---
#> 27005: -0.04505777 -3.4396243 -0.3492746 1.448371 -0.9764605
#> 27006: -0.39633083 -5.2603526 -0.5973411 2.423673 -1.4587488
#> 27007: 1.76945877 -4.0067720 0.8627796 3.911339 -2.3904738
#> 27008: 5.14945936 -1.2876422 2.6780972 4.573048 -3.9883673
#> 27009: 7.85265970 0.7570639 3.2915244 3.903461 -5.8100514
#> FC5 FC1 FC2 FC6 M1
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: -10.3604956 -8.741921 -11.687920 -3.2395220 -1.33440495
#> 2: -8.3586874 -9.393848 -11.007945 -2.0159216 -0.40914702
#> 3: -6.6766038 -10.921223 -9.508024 0.6382501 -0.02219653
#> 4: -5.3997726 -11.370429 -8.181183 2.3170936 -0.15380359
#> 5: -1.5244772 -10.140000 -8.618706 0.1669424 -0.42611933
#> ---
#> 27005: -3.1192555 7.583683 4.683777 2.0146487 -0.75850582
#> 27006: -5.0121384 7.003987 5.093409 2.6218574 -0.48889470
#> 27007: -3.8819036 8.010637 6.655658 2.4396117 0.37114978
#> 27008: 0.2056897 9.351544 7.915032 1.1819088 0.79920685
#> 27009: 3.5806384 9.694896 7.764079 -0.7410481 0.47170472
#> T7 C3 Cz C4 T8
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: -10.026085 -9.994508 -9.713416 -11.545010 -5.506052
#> 2: -10.864231 -11.186291 -10.363641 -10.096234 -13.692937
#> 3: -10.305115 -14.071175 -11.175298 -7.532410 -18.642357
#> 4: -6.952291 -15.679218 -11.470225 -5.610895 -15.585937
#> 5: -1.514339 -14.149639 -11.411907 -7.089185 -5.756573
#> ---
#> 27005: -2.933141 1.959429 5.739326 3.235288 7.357582
#> 27006: -3.713117 1.318202 5.491092 3.290012 7.295595
#> 27007: -2.321592 1.811074 6.128494 3.688938 5.087297
#> 27008: 1.119921 2.753958 6.793680 3.092779 3.427744
#> 27009: 3.754653 3.358357 6.357634 1.617870 3.171353
#> M2 CP5 CP1 CP2 CP6
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: 1.33440495 -10.124557 -21.182615 -8.225979 1.352515
#> 2: 0.40914702 -10.541845 -22.123146 -8.299847 2.918134
#> 3: 0.02219653 -10.097946 -22.904871 -7.499836 6.240794
#> 4: 0.15380359 -7.715628 -22.575096 -6.102085 8.873845
#> 5: 0.42611933 -3.972811 -21.122660 -5.780276 7.216280
#> ---
#> 27005: 0.75850582 2.440120 9.009402 2.962071 2.134945
#> 27006: 0.48889470 2.300604 8.520119 3.144351 2.515271
#> 27007: -0.37114978 2.277759 8.711225 3.692545 2.287699
#> 27008: -0.79920685 2.035310 8.742649 3.526225 -0.904506
#> 27009: -0.47170472 2.071527 8.072234 2.323087 -4.643136
#> P7 P3 Pz P4 P8
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: -12.080380 -10.113933 -8.703011 -4.20130539 3.195775
#> 2: -11.193981 -10.194810 -9.080425 -4.14209843 2.318590
#> 3: -7.487033 -9.285007 -8.754600 -2.61196470 3.541405
#> 4: -1.335482 -7.199755 -7.912488 -0.50822496 6.676203
#> 5: 4.918743 -4.848968 -7.416552 -0.01726842 8.177627
#> ---
#> 27005: -5.362492 3.755604 7.436291 0.44716191 -3.323942
#> 27006: -5.735914 3.123381 7.172704 0.63476968 -2.597961
#> 27007: -5.450908 3.175655 7.514575 0.96244740 -2.774142
#> 27008: -4.410063 3.246389 7.394914 0.24067569 -3.957345
#> 27009: -2.809917 2.920698 6.190672 -1.19312561 -4.774019
#> POz O1 Oz O2 EOGV
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: -8.369589 -8.4397917 -3.8788650 -0.1158402 -19.684998
#> 2: -9.067577 -8.5709276 -4.3982387 -0.5201874 -16.109802
#> 3: -7.452994 -5.2471170 -1.8378611 1.8578585 -11.800674
#> 4: -4.108239 1.1644255 3.2520020 6.4933400 -7.483185
#> 5: -1.417105 7.4992466 8.0737114 10.8989525 -6.017853
#> ---
#> 27005: 5.305985 -2.0515025 -0.6655829 -1.8001112 -6.660660
#> 27006: 5.463353 -1.7843865 -0.1968485 -1.1158936 -5.629734
#> 27007: 5.724925 -0.8298787 0.3083435 -0.6791936 -5.186114
#> 27008: 5.367867 0.6219659 0.7365036 -0.5318193 -4.111660
#> 27009: 4.392406 2.3162208 1.4108977 0.1259224 -2.589244
#> EOGH
#> <channel_dbl>
#> 1: -54.449097
#> 2: -68.097107
#> 3: -83.815216
#> 4: -100.941864
#> 5: -118.664459
#> ---
#> 27005: 6.173569
#> 27006: 4.975996
#> 27007: 3.522355
#> 27008: 2.911364
#> 27009: 3.616112
#>
#> # Events table:
#> .id .type .description .initial .final .channel
#> <int> <char> <char> <sample_int> <sample_int> <char>
#> 1: 1 Bad Interval Bad Min-Max -2499 -1905 Fp1
#> 2: 1 Bad Interval Bad Min-Max -2499 -1906 Fpz
#> 3: 1 Bad Interval Bad Min-Max -2499 -1905 Fp2
#> 4: 1 Bad Interval Bad Min-Max -2499 -1980 F7
#> 5: 1 Bad Interval Bad Min-Max -2499 -1939 Fz
#> ---
#> 150: 9 Bad Interval Bad Min-Max -1691 -1349 Fpz
#> 151: 8 Bad Interval Bad Min-Max 277 501 F8
#> 152: 9 Bad Interval Bad Min-Max -1672 -1435 F8
#> 153: 9 Stimulus s130 -369 -369 <NA>
#> 154: 9 Stimulus s70 1 1 <NA>
#>
#> # Segments table:
#> Key: <.id>
#> .id .recording segment type description
#> <int> <char> <int> <char> <char>
#> 1: 1 faces.vhdr 1 Stimulus s70
#> 2: 2 faces.vhdr 2 Stimulus s71
#> 3: 3 faces.vhdr 3 Stimulus s71
#> 4: 4 faces.vhdr 4 Stimulus s71
#> 5: 5 faces.vhdr 5 Stimulus s70
#> 6: 6 faces.vhdr 6 Stimulus s71
#> 7: 7 faces.vhdr 7 Stimulus s71
#> 8: 8 faces.vhdr 8 Stimulus s70
#> 9: 9 faces.vhdr 9 Stimulus s70
# Segments 500ms before and after the triggers all the triggers (which start with s)
data_faces_10_trials %>% eeg_segment(startsWith(.description, "s"))
#> # Total of 22 segments found.
#> # Object size in memory 2.9 Mb after segmentation.
#> # EEG data:
#>
#> # Signal table:
#> Key: <.id, .sample>
#> .id .sample Fp1 Fpz Fp2
#> <int> <sample_int> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: 1 -249 78.62610 41.76394 34.068588
#> 2: 1 -248 78.20166 41.62954 33.610832
#> 3: 1 -247 77.59616 41.61887 33.336830
#> 4: 1 -246 77.26508 41.62726 33.294086
#> 5: 1 -245 77.91381 41.76098 33.804604
#> ---
#> 10768: 22 -3 -20.42674 -14.87641 -10.669024
#> 10769: 22 -2 -19.79967 -13.65431 -9.698612
#> 10770: 22 -1 -18.61094 -13.91012 -10.128812
#> 10771: 22 0 -16.96312 -14.78610 -11.301287
#> 10772: 22 1 -15.31518 -15.08285 -11.722956
#> F7 F3 Fz F4 F8
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: 61.0350227 34.753330 23.639185 12.744570 -13.112861
#> 2: 61.1616707 34.804611 23.652182 12.445484 -14.556956
#> 3: 61.4098625 35.196716 24.083496 12.643650 -15.556440
#> 4: 61.8770332 36.010979 24.737810 13.239056 -15.982599
#> 5: 62.2362175 37.131126 25.163519 14.187828 -15.586605
#> ---
#> 10768: -0.5581126 -10.197008 -8.468801 -5.040645 -9.132243
#> 10769: -0.6716754 -8.732699 -7.252934 -3.377731 -8.813243
#> 10770: -0.7749598 -8.517799 -6.654031 -2.315117 -7.843120
#> 10771: -0.7414806 -9.084275 -6.622538 -1.845731 -6.556810
#> 10772: -0.3960888 -9.219618 -6.436240 -1.520404 -5.406781
#> FC5 FC1 FC2 FC6 M1
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: 30.128681 23.3925400 14.100018 -6.422720 12.4504757
#> 2: 30.302704 23.3768749 13.896832 -6.914124 12.6632786
#> 3: 30.541927 23.6706333 14.134787 -6.780725 12.4736462
#> 4: 30.937969 24.3952389 14.782417 -6.398545 12.6501217
#> 5: 31.381741 25.3208199 15.564636 -5.875418 13.6455660
#> ---
#> 10768: -7.535339 -2.3418787 -3.478385 -9.384595 0.8050708
#> 10769: -9.061241 -1.0433049 -1.930508 -7.475998 0.9832335
#> 10770: -7.603340 -0.6127751 -1.379790 -5.710404 1.2051768
#> 10771: -2.782797 -1.4022492 -1.640656 -4.640865 1.4103985
#> 10772: 2.897767 -2.5480108 -1.864611 -4.351316 1.1627738
#> T7 C3 Cz C4 T8
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: 16.627613068 19.3569126 13.314775 9.826402 -4.390102
#> 2: 16.668287277 19.8309460 12.891417 9.151336 -4.906647
#> 3: 16.746711731 20.4183846 12.895780 8.738137 -5.022333
#> 4: 17.144357681 21.2801056 13.359244 8.833906 -5.103370
#> 5: 17.746068954 22.1702232 13.766891 9.318307 -5.340479
#> ---
#> 10768: 0.003161311 -0.1895013 -4.354355 -8.362184 -5.082950
#> 10769: 0.534484148 1.4632750 -2.513818 -6.418050 -5.036983
#> 10770: 0.933975220 1.7615180 -1.322806 -5.185612 -1.183164
#> 10771: 1.373799086 -0.1813622 -1.508159 -5.173932 3.655909
#> 10772: 1.512201071 -3.2800312 -2.576048 -5.242217 5.829760
#> M2 CP5 CP1 CP2 CP6
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: -12.4504757 9.7454624 16.1605930 11.496984 2.658234
#> 2: -12.6632786 10.6645718 16.2766094 10.781269 2.442920
#> 3: -12.4736462 11.3375053 16.4452610 10.505079 2.383664
#> 4: -12.6501217 11.8110027 16.8414211 10.822355 2.384418
#> 5: -13.6455660 12.0349388 17.1879940 11.238800 2.295322
#> ---
#> 10768: -0.8050708 3.3321576 0.7318851 -8.517914 -14.386089
#> 10769: -0.9832335 3.6177154 2.1529536 -6.548975 -11.468288
#> 10770: -1.2051768 3.1916180 2.6771717 -5.318815 -8.818744
#> 10771: -1.4103985 1.9870222 1.8302985 -5.515146 -7.753020
#> 10772: -1.1627738 0.5995106 0.1455368 -6.459312 -7.319424
#> P7 P3 Pz P4 P8
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: -1.7451426 7.0334272 8.180294 4.775116 -4.629857
#> 2: -0.2636484 7.1291485 7.601710 4.440700 -4.131961
#> 3: 0.5830721 6.8668699 7.199402 4.265406 -3.937120
#> 4: 0.9209399 6.5586395 7.161300 4.300853 -4.057757
#> 5: 0.9128329 6.2931347 7.174585 4.265417 -4.283892
#> ---
#> 10768: 7.0251837 0.5382314 -4.589949 -10.580815 -11.031232
#> 10769: 6.4313159 0.9306827 -3.111303 -8.619126 -9.325615
#> 10770: 4.4492149 0.3993354 -2.119561 -6.606555 -6.365070
#> 10771: 2.3532932 -1.1857104 -2.376006 -5.663703 -4.065647
#> 10772: 1.0884135 -3.2549555 -3.662545 -5.691663 -3.320732
#> POz O1 Oz O2 EOGV
#> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl> <channel_dbl>
#> 1: 2.716347 -1.8138508 -1.052482 -3.7898300 221.72339
#> 2: 2.882783 0.9058186 1.491970 -1.8266290 222.24321
#> 3: 3.019314 3.1099281 4.017059 -0.1130857 221.69824
#> 4: 3.093190 4.1138868 5.513156 0.8811790 219.79274
#> 5: 2.720414 3.4851596 4.737876 0.5716844 216.66183
#> ---
#> 10768: -5.136292 1.4443915 -5.164615 -8.2288170 18.41424
#> 10769: -3.689569 1.4091530 -3.915735 -6.4314718 19.22052
#> 10770: -2.319134 0.5369543 -2.351812 -3.4845843 19.74028
#> 10771: -1.927569 -0.5624531 -1.339175 -1.1418194 19.20309
#> 10772: -2.687999 -1.2014523 -1.284558 -0.7185705 18.72752
#> EOGH
#> <channel_dbl>
#> 1: 186.836212
#> 2: 185.994202
#> 3: 186.654510
#> 4: 186.596741
#> 5: 184.106873
#> ---
#> 10768: 6.434383
#> 10769: 7.837689
#> 10770: 8.659687
#> 10771: 8.609533
#> 10772: 8.829977
#>
#> # Events table:
#> .id .type .description .initial .final .channel
#> <int> <char> <char> <sample_int> <sample_int> <char>
#> 1: 1 Bad Interval Bad Min-Max -249 139 F8
#> 2: 1 Bad Interval Bad Min-Max -249 -210 F7
#> 3: 1 Bad Interval Bad Min-Max -215 190 Fp1
#> 4: 1 Bad Interval Bad Min-Max -214 175 Fp2
#> 5: 1 Bad Interval Bad Min-Max -214 180 Fpz
#> 6: 1 Bad Interval Bad Min-Max -197 144 Fz
#> 7: 1 Bad Interval Bad Min-Max -197 138 F4
#> 8: 1 Bad Interval Bad Min-Max -195 141 F3
#> 9: 1 Bad Interval Bad Min-Max -191 119 F7
#> 10: 1 Stimulus s5 1 1 <NA>
#> 11: 2 Stimulus s101 1 1 <NA>
#> 12: 3 Bad Interval Bad Min-Max -249 147 Fp1
#> 13: 4 Bad Interval Bad Min-Max -249 -78 Fp1
#> 14: 3 Bad Interval Bad Min-Max -249 147 Fpz
#> 15: 4 Bad Interval Bad Min-Max -249 -78 Fpz
#> 16: 3 Bad Interval Bad Min-Max -249 148 Fp2
#> 17: 4 Bad Interval Bad Min-Max -249 -77 Fp2
#> 18: 3 Bad Interval Bad Min-Max -249 122 F8
#> 19: 4 Bad Interval Bad Min-Max -249 -103 F8
#> 20: 3 Bad Interval Bad Min-Max -231 120 Fz
#> 21: 4 Bad Interval Bad Min-Max -249 -105 Fz
#> 22: 3 Bad Interval Bad Min-Max -230 119 F4
#> 23: 4 Bad Interval Bad Min-Max -249 -106 F4
#> 24: 3 Bad Interval Bad Min-Max -229 118 F3
#> 25: 4 Bad Interval Bad Min-Max -249 -107 F3
#> 26: 3 Bad Interval Bad Min-Max -224 76 F7
#> 27: 4 Bad Interval Bad Min-Max -249 -149 F7
#> 28: 3 Bad Interval Bad Min-Max -222 70 FC2
#> 29: 4 Bad Interval Bad Min-Max -249 -155 FC2
#> 30: 3 Bad Interval Bad Min-Max -222 71 FC1
#> 31: 4 Bad Interval Bad Min-Max -249 -154 FC1
#> 32: 3 Bad Interval Bad Min-Max -221 62 FC6
#> 33: 4 Bad Interval Bad Min-Max -249 -163 FC6
#> 34: 3 Bad Interval Bad Min-Max -217 70 FC5
#> 35: 4 Bad Interval Bad Min-Max -249 -155 FC5
#> 36: 3 Bad Interval Bad Min-Max -208 66 C3
#> 37: 4 Bad Interval Bad Min-Max -249 -159 C3
#> 38: 3 Bad Interval Bad Min-Max -205 66 Cz
#> 39: 4 Bad Interval Bad Min-Max -249 -159 Cz
#> 40: 3 Bad Interval Bad Min-Max -202 58 CP1
#> 41: 4 Bad Interval Bad Min-Max -249 -167 CP1
#> 42: 3 Bad Interval Bad Min-Max -200 56 C4
#> 43: 4 Bad Interval Bad Min-Max -249 -169 C4
#> 44: 3 Bad Interval Bad Min-Max -196 54 CP2
#> 45: 4 Bad Interval Bad Min-Max -249 -171 CP2
#> 46: 3 Bad Interval Bad Min-Max -191 51 Pz
#> 47: 4 Bad Interval Bad Min-Max -249 -174 Pz
#> 48: 3 Bad Interval Bad Min-Max -186 46 P3
#> 49: 4 Bad Interval Bad Min-Max -249 -179 P3
#> 50: 3 Bad Interval Bad Min-Max -186 -2 CP5
#> 51: 4 Bad Interval Bad Min-Max -249 -227 CP5
#> 52: 3 Stimulus s111 1 1 <NA>
#> 53: 4 Stimulus s111 -224 -224 <NA>
#> 54: 3 Stimulus s130 226 226 <NA>
#> 55: 4 Stimulus s130 1 1 <NA>
#> 56: 5 Stimulus s70 1 1 <NA>
#> 57: 6 Stimulus s130 1 1 <NA>
#> 58: 7 Stimulus s71 1 1 <NA>
#> 59: 8 Stimulus s130 1 1 <NA>
#> 60: 9 Stimulus s71 1 1 <NA>
#> 61: 10 Stimulus s130 1 1 <NA>
#> 62: 11 Stimulus s71 1 1 <NA>
#> 63: 12 Stimulus s130 1 1 <NA>
#> 64: 13 Stimulus s70 1 1 <NA>
#> 65: 14 Stimulus s130 1 1 <NA>
#> 66: 15 Stimulus s71 1 1 <NA>
#> 67: 16 Stimulus s130 1 1 <NA>
#> 68: 17 Stimulus s71 1 1 <NA>
#> 69: 18 Stimulus s130 1 1 <NA>
#> 70: 19 Stimulus s70 1 1 <NA>
#> 71: 20 Stimulus s130 1 1 <NA>
#> 72: 21 Stimulus s70 1 1 <NA>
#> 73: 22 Stimulus s130 1 1 <NA>
#> .id .type .description .initial .final .channel
#>
#> # Segments table:
#> Key: <.id>
#> .id .recording segment type description
#> <int> <char> <int> <char> <char>
#> 1: 1 faces.vhdr 1 Stimulus s5
#> 2: 2 faces.vhdr 2 Stimulus s101
#> 3: 3 faces.vhdr 3 Stimulus s111
#> 4: 4 faces.vhdr 4 Stimulus s130
#> 5: 5 faces.vhdr 5 Stimulus s70
#> 6: 6 faces.vhdr 6 Stimulus s130
#> 7: 7 faces.vhdr 7 Stimulus s71
#> 8: 8 faces.vhdr 8 Stimulus s130
#> 9: 9 faces.vhdr 9 Stimulus s71
#> 10: 10 faces.vhdr 10 Stimulus s130
#> 11: 11 faces.vhdr 11 Stimulus s71
#> 12: 12 faces.vhdr 12 Stimulus s130
#> 13: 13 faces.vhdr 13 Stimulus s70
#> 14: 14 faces.vhdr 14 Stimulus s130
#> 15: 15 faces.vhdr 15 Stimulus s71
#> 16: 16 faces.vhdr 16 Stimulus s130
#> 17: 17 faces.vhdr 17 Stimulus s71
#> 18: 18 faces.vhdr 18 Stimulus s130
#> 19: 19 faces.vhdr 19 Stimulus s70
#> 20: 20 faces.vhdr 20 Stimulus s130
#> 21: 21 faces.vhdr 21 Stimulus s70
#> 22: 22 faces.vhdr 22 Stimulus s130
#> .id .recording segment type description